[Flexradio] 5000A with V/U, RX2, ATU on eBay

[John Ackermann N8UR]

I ended up listing my fully loaded 5000A on eBay:

http://www.ebay.com/itm/190833186647

In case the link doesn't work, it's item number 190833186647

73,
John

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Re: [Flexradio] V/U antenna configuration?

[John Ackermann N8UR]

Thanks, Alan.  I don't have my 5K running at the moment (no antennas installed 
yet) but am planning for a portable operation and wanted to figure out antenna 
cabling.

73,
John

On Apr 26, 2012, at 8:09 PM, Alan NV8A  wrote:

> On 04/26/12 06:17 pm, John Ackermann N8UR wrote:
>>> Can the 5000 V/U be configured to put both 2m and 70cm on a single antenna 
>>> connector, or are you required to use separate connectors for each band?
> 
> There are separate connectors. AFAIK, there is no way of combining the 
> signals onto one. I use a duplexer.
> 
> 73
> 
> Alan NV8A
> 

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[Flexradio] V/U antenna configuration?

[John Ackermann N8UR]

> Can the 5000 V/U be configured to put both 2m and 70cm on a single antenna 
> connector, or are you required to use separate connectors for each band?
> 
> Thanks,
> 
> John

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Re: [Flexradio] [FlexRadio] 3-pin xlr microphone flex-5000

[John Ackermann N8UR]

Larry Rappaport said the following on 12/11/2009 08:09 PM:

Well, you guys are ignoring IRLP for some reason.  That uses a free codec -
FreeVOIP, I think.  That is completely free, in use worldwide, uses Linux,
etc.  What's wrong with that?  Basically, it's a free version of D-Star.  


I like IRLP a lot, but it's a fundamentally different implementation 
using traditional FM radios and analog repeaters; the digital component 
only happens on the internet link between repeaters where bandwidth 
isn't the same issue as it is on RF.


D-Star is digital all the way through, which allows some interesting 
things that you can't do with IRLP such as automatic routing and 
selective calling.  (And I'm sure other things as well; I'm not a D-Star 
expert.  I'm sure others can do a much better job explaining its uses.)


John

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Re: [Flexradio] [FlexRadio] 3-pin xlr microphone flex-5000

[John Ackermann N8UR]

Alan NV8A wrote:

D-Star is not proprietary to Icom. It's my understanding that it was 
developed as a cooperative venture between JARL, the manufacturers, and 
the Japanese government. I think that Kenwood sells D-Star rigs in Japan 
but for whatever reason doesn't in the USA.


Not to go too far down a rat hole, but while you're correct that the 
D-Star protocol at the high level is not proprietary, the digital voice 
codec (AMBE) that D-Star uses is patent-encumbered and available only as 
a hardware chip or through a very expensive software license.


That means, for example, that until the patent expires no one can write 
an SDR program to let your Flex 5000 with V/U module talk through a 
D-Star repeater.  You'll need to buy the DVDongle or equivalent hardware 
to provide the digital voice function.  Alternatively, you can pay more 
than $100K (according to educated guesses) for a license to implement 
AMBE in a closed-source program; a license for an open source version is 
simply unobtainable.


So, for practical purposes, D-Star digital voice today *is* a 
proprietary system, though the proprietary party isn't Icom, but the 
patent holder, Digital Voice Systems, Inc.


The way to solve the problem is to use a non-patented CODEC, but good 
ones for narrow bandwidth applications are hard to find.  As someone 
earlier noted, progress is being made in that area, though.*


John

* Another wrinkle is that a new CODEC almost by definition won't be 
compatible with AMBE, so you couldn't drop it into an existing D-Star 
repeater system without some sort of decode-then-recode process at the 
repeater, which adds expense and complexity, and is likely to reduce 
voice quality.


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[Flexradio] VHF/UHF capability matrix?

[John Ackermann N8UR]

I haven't been able to find anything that describes the mode/band 
operation and antenna selection matrix for the 5000 with the VHF/UHF 
upgrade installed.  In other words, what bands are available on what 
rear panel connectors, and what combination of HF/6M/VHF/UHF can operate 
simultaneously?  (for extra credit, add how RX2 fits into the mix :-) )


Is that info available somewhere, and if not, can it be?

Thanks,

John


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Re: [Flexradio] Frequecy Off?

[John Ackermann N8UR]

I've used the F5K with an external reference and can verify that it 
works; you can see WWV's carrier jump when you plug and unplug the 
external reference.


However, perhaps Tim could verify something for the time-nuts amongst 
us: is the clock for the ADC locked to the same reference as the DDSs, 
or is it free running?


If a free-running crystal feeds the ADC/DAC clocks, there is going to be 
a frequency error due to that, even if an external reference is used. 
It's likely to be small(1) and it will not scale with frequency(2).


(And just to answer a question that's likely to be asked, the crystal in 
the PC does *not* contribute any error since the PC isn't doing any 
analog processing.)


John

(1) Assuming the ADC/DAC are configured like a typical sound card, the 
clock crystal is running at something between 10 and 30 MHz, and is 
effectively divided down to the sample rate by the ADC/DAC chips.  That 
division both reduces frequency offset and drift, and improves phase 
noise.  The couple of Delta 44 cards I"ve looked at had a clocking error 
of less than 1 Hertz, and were quite stable when the computer they were 
housed in was at a stable operating temperature.


(2) Since the ADC/DAC are at baseband, the clock doesn't go through any 
multiplication related to the operating frequency.  Any offset is a 
simple additive error that applies equally at all RF frequencies.


Mark Whatley wrote:

I was going to ask a question here today and was surprised to find that it
was answered (I think) before I asked it! You guys are good!

 


I was going to ask if I connect my Z3801's 10 MHz output to my F5K will the
Flex inherit the same accuracy as the standard? 

 


I think the Stu might have answered that in his post but thought I would ask
anyway. Seems like I have seen other radios that allow external references
but they also have some oscillator along the way that is not locked to the
reference - like a BFO oscillator - which spoils the overall accuracy.



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Re: [Flexradio] Venting about VAC 4 with SDR 1.18.1 (but I know I am somehow the problem)

[John Ackermann N8UR]

I'll also vote for Shuttles.  I have had three of them and my current 
Core II Duo box runs PowerSDR very nicely.  They are small and *very* 
quiet -- almost silent, in fact.


John


Tim Ellison said the following on 07/11/2009 12:27 PM:

Although Neal will  argue the point (and I appreciate various points of view), I have had good 
luck with the small cubic form factor Shuttle xPC PCs.  For less than $650, you can get a nice 
Core 2 Duo machine that is almost identical to the size and shape of a FLEX-5000.  While I was 
doing the Raleigh hamfest this April with this setup, a lot of folks didn't know which one was 
the radio and which one was the computer.  What they did notice was the 24" wide screen 
LCD display, which is really the "front panel" of the radio.  It isn't exactly 
portable in the classic sense of the word, but it is definitely luggable.


-Tim

-Original Message-
From: Mark Lunday [mailto:mlun...@nc.rr.com] 
Sent: Saturday, July 11, 2009 11:42 AM

To: 'Bob McGwier'
Cc: Tim Ellison; 'Flexradio'
Subject: RE: [Flexradio] Venting about VAC 4 with SDR 1.18.1 (but I know I am 
somehow the problem)

Bob

This is TERRIFIC information.  Given the low cost of desktops these days, I 
could have saved myself the pain by just getting one instead of trying to make 
this laptop work properly.

Keep up the GREAT work at Flex!  



Mark Lunday
WD4ELG
wd4...@arrl.net
http://wd4elg.net




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[Flexradio] Using SDR-1000 amplifier stand-alone?

[John Ackermann N8UR]

I am contemplating what to do with my SDR-1K and thinking it might make 
sense to revert it to a QRP unit, pulling the amplifier and tuner out 
for use with other QRP rigs (like my HPSDR stack).


I know there is some interface cabling between the PIO board and the 
amplifier.  Is that an insurmountable issue in using the amp and tuner 
alone?


If anyone has made this work, I'd like to hear about it.

Thanks!

John


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Re: [Flexradio] [FlexRadio] VAC with Vista X64

[John Ackermann N8UR]

Lux, James P wrote:

"Being able to buy it conveniently" is even different.  
-- you call microsoft

"Oh you want to buy XP for your system. Sure we still support that for people 
needing to keep their XP machines on the factory floor working.  You'll need to talk to 
one of our Microsoft Industrial Embedded partners.  We've got two in North America, would 
you like the one in California, or the one in Georgia?"
-- you call the rep in California
"Good afternoon, ACME Process Controls, may I help you?"
-I'd like to get a copy of Windows XP
"Oh, you'll need to talk to our small sales department, but he's out of the office 
right now, may I take a message?"
-three days later, he calls back and leaves a message
"Hi, this is Bob, and I'm your rep for Microsoft Industrial Embedded. How many 
controllers are you retrofitting?"
- You finally get a hold of Bob, and tell him you need one copy of XP
"No problem. Let's see now, I assume your hardware is on the Microsoft Approved Hardware List? 
Can you just read off the model number and validation sticker."..."oh, it's not on the 
list and you don't have a sticker?  You need to talk to OEM sales, then."
--- A week later, you finally talk to OEM sales.
" Sure, we'll set you up.  We've got very attractive licensing terms. You can get 
100 copies for only $10,000, plus an annual support fee of $10/year for each copy that's 
installed"


Just as a data point, I bought a new Lenovo Thinkpad T500 laptop a 
couple of months ago, and as part of the on-line order process was able 
to specify XP Pro instead of Vista just by checking a box.  No extra charge.


John

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[Flexradio] SDR-1000 for sale

[John Ackermann N8UR]

I posted this shortly before Christmas, but had no takers at the price I
asked then, so am giving it another try.  Rather than posting a price,
please contact me off-list at j...@febo.com and we'll see if we can make
a deal.

FOR SALE:  SDR-1000 with 100 watt amplifier, ATU, and DEMI 2M
transverter.  Also includes parallel to USB converter cable and
SDR-LPF/CBL audio cable.

Not sure if this is the serial number or not, but a label on the bottom
says "ASM-0437004".

Returned to Flex in July 2007 for checkout, installation of transverter,
and upgrade with all ECOs (including update to 8 pin mic connector).
I'll provide the service report (dated 2 July 2007) showing performance
verification at that time.

Radio is in as-new condition with very little use since the 2007 service.

Currently configured for external frequency reference; I will include
the original 200 MHz oscillator with the unit, and can reinstall it and
reconfigure the unit for internal frequency reference if desired.

Please contact me off-list if you're interested.

Thanks!

John N8UR

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[Flexradio] Record both RX1 and RX2 to WAV file?

[John Ackermann N8UR]

I may not have been searching in the right way, but I couldn't find out
if it's possible to record both RX1 and RX2 to a WAV file
simultaneously, preferably one RX in each (left/right) channel.

Can that be done?

Thanks,

John

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[Flexradio] Unassembled UCB kit for sale

[John Ackermann N8UR]

I discovered that I have an unassembled UCB complete kit (including
relays) that I won't need.  This is Tony Parks'/Phil Theis' original
version, not the later "Poor Man's UCB".

I paid $99 plus shipping for it in early 2007.  Best offer over $50 in
the next 72 hours gets it.

Thanks!

73,
John

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[Flexradio] SDR-1000/PA/ATU/XVTR for sale

[John Ackermann N8UR]

Hi --

Too many radios, too little time...

SDR-1000 in as-new condition with 100 watt amp, internal antenna tuner,
internal DEMI transverter, USB/Parallel adapter cable.

Serviced by Flex in July 2007 with all ECOs and updated 8 pin mic
connector installed; test report included with the radio.  Virtually
zero use since then.

Currently configured for external 10 MHz reference; I can change that
back for the buyer if desired.

Asking $1200 plus shipping (from Dayton, OH) for the package.  I also
have an unassembled UCB kit available separately (see my other posting).

73,
John N8UR

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Re: [Flexradio] Small LCD monitor?

[John Ackermann N8UR]

Yup, that's the problem! ($350 each, to spare the rest of you looking it 
 up.)


John


Tim Ellison wrote:

John,

I googled on your text string "12-14 inch, 1024x768 LCD monitor" and found:

http://www.nextag.com/Miracle-Business-Inc-LT12B-88114962/prices-html?nxtg=13b70a1c0533-1050D7697472EE56
http://www.esis.com.au/LCD-Monitors/LCD-Monitors.htm#LCD_12_14

They are rare creatures and [Small != cheap]


-Tim

-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Ackermann 
N8UR
Sent: Thursday, October 02, 2008 11:32 AM
To: flexradio@flex-radio.biz
Subject: [Flexradio] Small LCD monitor?

I think this has been discussed here before, but I can't find the references...

I'd like to find a 12-14 inch, 1024x768 LCD monitor to fit under the shelf on 
my desk and to display PowerSDR in a dual-monitor configuration with a larger 
monitor running other applications.

Small monitors seem hard to find, except in expensive configurations for 
industrial use.

Anyone know of something that's pre-packaged (i.e., not a notebook display that 
would require a bunch of integration) for a reasonable price?

Thanks,

John

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[Flexradio] Small LCD monitor?

[John Ackermann N8UR]

I think this has been discussed here before, but I can't find the 
references...


I'd like to find a 12-14 inch, 1024x768 LCD monitor to fit under the 
shelf on my desk and to display PowerSDR in a dual-monitor configuration 
with a larger monitor running other applications.


Small monitors seem hard to find, except in expensive configurations for 
industrial use.


Anyone know of something that's pre-packaged (i.e., not a notebook 
display that would require a bunch of integration) for a reasonable price?


Thanks,

John

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[Flexradio] RX2 -- Waterfall problem still in 1.14.0?

[John Ackermann N8UR]

I think I reported this earlier, but didn't get feedback as to whether
anyone else has seen this, so I'll ask again, now that I have 1.14.0 and
am still seeing the same thing...

If I select the waterfall display for both RX1 and RX2, it appears that
the RX2 waterfall is simply a duplicate of the RX1.

If RX1 is using another mode (e.g., panadapter), the RX2 waterfall seems
to be more-or-less correct (there is a fixed blue line about 10.6 kHz
below the tuned frequency that seems wrong).  But as soon as I switch
RX1 to waterfall, the RX2 waterfall simply copies the RX1 display.

So, is it just me, or is there a bug?

BTW -- I'm having great fun tuning around with RX1 and RX2 in a
diversity mode, using my vertical on one RX and horizontal wire with the
other.  It's very interesting to see what paths work best on one antenna
versus the other, in real time.

John

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Re: [Flexradio] K6JCA display improvements

[John Ackermann N8UR]

Eric, since you're asking for input...

I already filed an enhancement suggestion for this, but two thoughts
about antenna selection:

1.  Since you use screen real estate to show the selected antennas (on
the left, about 1/3 up from the bottom), why not turn those into drop
boxes so you can do at least basic antenna selection without having to
go to the top menu bar?

2.  Ability to name antennas would be nice.  I know the screen real
estate is limited, but a 4 character abbreviation would be enough to be
useful.

Thanks,

John


Eric Wachsmann said the following on 08/01/2008 03:19 PM:
> Excellent questions.
> 
> The split waterfall/panadapter feature is very nice.  We appreciate Jeff
> taking the initiative to continue to innovate useful features like this.
> Unfortunately, about the same time, we were incorporating RX2 support.  The
> conflicts between what were added to support RX2 and the existing
> Pan/Waterfall code were unfortunately too far beyond reconciling to get into
> the official release easily.  This feature is definitely slated for 1.13.x
> versions.  Input is welcome on this ... especially with regard to how to
> handle RX2 and the split display options.
> 
> As for the appearance controls, we would like to find a way to handle the
> changes in a more automated fashion so that we don't have to manually change
> those functions each time controls are added/removed.  That maintenance
> really adds up over time.
> 
> 
> Eric Wachsmann
> FlexRadio Systems
> 
> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Jesse N4BFD
> Sent: Friday, August 01, 2008 1:12 PM
> To: flexradio@flex-radio.biz
> Subject: [Flexradio] K6JCA display improvements
> 
>> Hello,
>>
> I was just curious as to why the added features of the K6JCA SVN release
> such as the split waterfall/panadapter, and the ability to change the
> coloring of the overall GUI have not been added to the trunk?  It has been
> out for many months now, and I prefer to use this release due to it being
> easier on the eyes after long hours of use after adjusting the appearence to
> something that I like.  However, many other features of course have been
> added to the trunk, so I am starting to miss out on somethings.
> 
> N4BFD
> 
> 
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> http://www.flex-radio.com/
> 
> 
> 


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Re: [Flexradio] New Model from FlexRadio?

[John Ackermann N8UR]

*That* is impressive!

John

PS -- I went to the "Round the Horne Revisited" stage show a few years
ago.  Another great British radio show.


Alan NV8A said the following on 07/26/2008 10:20 PM:
> Probably I can do you one better: I attended one of their recording 
> sessions back in the 1950s.
> 
> 73
> 
> Alan NV8A
> 
> 
> On 07/26/08 07:55 pm Frank Brickle wrote:
> 
>> Sapristi niakos! Found out! Precisely -- and yours also, John, you silly,
>> twisted boy.
>>
>> 73
>> Frank
>> AB2KT
>>
>> On Sat, Jul 26, 2008 at 4:31 PM, John Ackermann N8UR <[EMAIL PROTECTED]> 
>> wrote:
>>
>>> Not surprising -- I recall Frank's familiarity with The Highly-Esteemed
>>> Goon Show!
>>>
>>> John


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Re: [Flexradio] New Model from FlexRadio?

[John Ackermann N8UR]

Not surprising -- I recall Frank's familiarity with The Highly-Esteemed
Goon Show!

John


Lee Mushel said the following on 07/26/2008 06:34 PM:
> Frank,
> 
> I can't believe it! someone else who uses the term "highly-esteemed!"   My
> use goes back 40 years to one of my first jobs and the context is usually
> one of sarcasm.   But no matter.   Just as long as it doesn't disappear!
> People who know me know that most of my stuff, even that of Asian origin, is
> "highly-esteemed!"  I was having a bad day but you've turned it around!
> 
> 73
> 
> Lee   K9WRU
> - Original Message - 
> From: "Frank Brickle" <[EMAIL PROTECTED]>
> To: "Tim Ellison (W4TME)" <[EMAIL PROTECTED]>
> Cc: <[EMAIL PROTECTED]>; 
> Sent: Saturday, July 26, 2008 1:32 PM
> Subject: Re: [Flexradio] New Model from FlexRadio?
> 
> 
>> Tim is exactly right. And anyway, we're out of the closet in admitting
> that
>> the highly-esteemed "new architecture" is really just some "old
>> architecture" applied to a mildly novel problem. Calling the prototype VR
>> the new radio might be just a sliver less pretentious than continuing to
>> call it by a name that implies something profoundly revolutionary :-)
>>
>> 73
>> Frank
>> AB2KT
>>
>> On Sat, Jul 26, 2008 at 10:34 AM, Tim Ellison (W4TME)
> <[EMAIL PROTECTED]>wrote:
>>> No new physical radio, per se.  When you match the new VR code with the
>>> FLEX-5000 and the SDR-1000, you will have new software defined radios
> that
>>> are going to be very different from what you have today with PowerSDR
> 1.x.
>>> That is what was promised to have running for Dayton 09.  In the
> software
>>> defined domain of programmers, the hardware is not really the radio, it
> is
>>> just a source and destination for I/Q data streams for some black box to
>>> make RF out of.
>>>
>>> - Tim
>>> -
>>> FRS Internet Systems Administrator
>>> W4TME
>>>
>>>
>>> - Original Message -
>>> From: "Kirb Nesbitt" <[EMAIL PROTECTED]>
>>> To: 
>>> Sent: Saturday, July 26, 2008 12:22 PM
>>> Subject: [Flexradio] New Model from FlexRadio?
>>>
>>>
 New Radio? Please step up and speak into the microphone, sir. :-)

 Frank, AB2KT said-
 " Sooner than you might think. We are moving very fast now towards an
 earlier
 exposure of alpha code for the new radio than we'd previously
> announced
 (Dayton next)."

 Kirb - VE6IV


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>>>
>>>
>>
>> -- 
>> Travelling by airplane in the US is nothing more than mass training of
>> Americans to the requirements of the coming police state. The whole point
> is
>> to make you learn to acquiesce without question, en masse, to completely
>> absurd directives by dull functionaries wearing uniforms. -- Digby
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Re: [Flexradio] Audio mixer/amp recommendation?

[John Ackermann N8UR]

Thanks, Dale.  I was hoping to find a single unit rather than a separate
mixer and amp setup, but what you describe sure offers flexibility.
Thanks for the tip!

John


Dale Boresz said the following on 07/26/2008 03:54 PM:
> Hello John,
> 
> I've been using one of these:
> <
> http://www.guitarcenter.com/Behringer-EURORACK-Pro-RX1602-Line-Mixer-631243-i1153486.gc
>>
> 
> (Behringer Eurorack Pro RX1602 Line Mixer)  for a couple of years, to
> route the outputs from several radios (including the FLEX-5000 and
> SDR-1000), several computers, and a satellite radio, into an audio
> preamp/power amp which in turn drives a pair of high quality
> non-amplified speakers.
> 
> It works great, and provides independent volume, balance, and muting for
> each of the 8 stereo input channels.
> 
> 73, Dale
> WA8SRA
> 
> 
> John Ackermann N8UR wrote:
>> I'm thinking that instead of two separate sets of amplified speakers to
>> support the Flex 5000 audio out, as well as the computer's audio out, it
>> might be more efficient to use a single box that would be a mixer and
>> amplifier to drive a single set of unamplified speakers.
>>
>> Has anyone done something like this?  Any recommendations on an
>> appropriate mixer/amp?
>>
>> Thanks,
>>
>> John
>>
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>>
>>
>>   
> 
> 
> 


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Re: [Flexradio] Audio mixer/amp recommendation?

[John Ackermann N8UR]

Those are an interesting idea, Mike.  Thanks!

Re the ferrites -- I take it you had some RF issues.  Were you able to
calm things down?

John


Mike Schelly said the following on 07/26/2008 03:40 PM:
> A pair of Behringer MS20 or 40's will accommodate two line inputs with
> separate volume levels, very nice sound. Some shacks may require a few
> ferrites ;-)
> 
> Mike K4EAR 
> 
> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of John Ackermann N8UR
> Sent: Saturday, July 26, 2008 12:59 PM
> To: Flex Group
> Subject: [Flexradio] Audio mixer/amp recommendation?
> 
> I'm thinking that instead of two separate sets of amplified speakers to
> support the Flex 5000 audio out, as well as the computer's audio out, it
> might be more efficient to use a single box that would be a mixer and
> amplifier to drive a single set of unamplified speakers.
> 
> Has anyone done something like this?  Any recommendations on an appropriate
> mixer/amp?
> 
> Thanks,
> 
> John
> 
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> Checked by AVG. 
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[Flexradio] Audio mixer/amp recommendation?

[John Ackermann N8UR]

I'm thinking that instead of two separate sets of amplified speakers to
support the Flex 5000 audio out, as well as the computer's audio out, it
might be more efficient to use a single box that would be a mixer and
amplifier to drive a single set of unamplified speakers.

Has anyone done something like this?  Any recommendations on an
appropriate mixer/amp?

Thanks,

John

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[Flexradio] RX2 Waterfall problem?

[John Ackermann N8UR]

I just installed 1.12.1 and continue to see a bug I noticed earlier, but
didn't have a chance to question then...

When I am using RX1 and RX2, and set both displays to waterfall, it
appears that the RX2 waterfall is simply a copy of the RX1 display,
though the legend of the lower waterfall matches the RX2 frequency.  If
RX1 is set to panadapter, and RX2 is set to waterfall, there is no RX2
display at all.

So, it appears that the only functional display for RX2 is panadapter.
Is this a known problem?

73,
John

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Re: [Flexradio] Worked FDMDV mode w/ FLEX-5000A...

[John Ackermann N8UR]

Mike Naruta wrote:

> I once became the IT Manager for a company that used
> MAI Basic Four equipment.  They used special PROMs in
> their terminal and printers that were only available
> from MAI Basic Four, even though the equipment was
> common Printronix, etc.  The PROM in the printers
> would repeat back the print line exactly as sent by
> the host.  If the host didn't get the line back within
> a short time, it refused to send out any more print
> lines.  Imagine trying to send that over stat Muxes.
> I got rid of that MAI Basic Four stuff as soon as I
> was able to.

Interesting... MAI was a party to one of the key cases in the 
development of computer law.  They had a provision in their license 
agreement that prohibited anyone other than the owner from running the 
software.  Peak was an independent service company that MAI didn't like. 
  Since you need to boot the computer to diagnose it, MAI sued Peak for 
copyright infringement.

The bad news is that MAI won the lawsuit.

The good news is that the decision, while technically correct, was so 
wrong in a practical sense that Congress amended the copyright act soon 
after, and now there is an explicit permission to run software as 
necessary to service equipment in which that software is installed.

{Warning: that was a brief summary from memory; I may have a detail or 
two wrong.]

John

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Re: [Flexradio] TCXO

[John Ackermann N8UR]

Frank, the 50 ohm resistor was added for two reasons:  first, it
provides a termination for the coax that's feed the signal and in theory
that minimize jitter due to ringing on the coax, and second, the
unloaded P-P voltage from oscillators rated at, say, 6dBm into 50 ohms,
is high enough that it could exceed the DDS chip's input rating.  By
providing a load, the resistor keeps the voltage to a safe level.

So, if you have a reference with marginal output, removing the resistor
might make it work.  You'd lose the theoretical jitter protection, but
in most cases that's probably a non-issue in the real world.

John


Frank Mayer said the following on 11/01/2007 05:24 AM:
> I just can't seem to find a source for one of these for my SDR-1000.  That 
> guy K2ws won't answer my emails for some reason and my search for anyone to 
> sell me just one has been futile.  All I get is "we need your company 
> information"  Any way I found a 10mhz TCXO on ebay for 39 bucks that has an 
> output of 1V p-p but has no spec sheet to tell me into what load.  I have not 
> received the unit as of yet.  I understand from the Flex documentaion that 
> the rig requires from 4dbm to 14dbm output into 50 ohms.  It tells you when 
> you install the external TCXO kit to put a 50 ohm resistor across the BNC 
> connector for a load.  I'm concerned that the TCXO that I am getting won't 
> have that kind of output into 50 ohms.  I wonder if raising that value of 
> that resistor would work ok?  Any one have experience with installing one of 
> these?
> Thanks,
> Frank  WA3JBT
> -- next part --
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> 
> 


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[Flexradio] Flex 5000A hum problem

[John Ackermann N8UR]

I just hooked my 5000A to its new computer (a Shuttle XPC with 2.6 GHz
dual core, 2GB RAM, good quality video card, running XP Pro).

When I select 192ksamples, the CPU load is nice and low at about 15%,
but there is a very bad hum (really, more like a low frequency buzz)
that rides on any input signal.  It's not noticeable on noise, but the
stronger the signal in the passband, the louder the noise.

If I slow the sample rate down to 96ksamples, the noise is dramatically
better.  It's still there, but low enough in amplitude to be almost
unnoticeable.  48ksamples gives the same result -- if you listen, it's
there, but it's not particularly annoying.

It's not a loop in the antenna system as such; if I remove the antenna
but touch my finger to the SO-239 when tuned to a strong local AM
station, the noise is still there.

I'm listening with headphones plugged into the 5000A front panel jack.
There's no other audio connection (no mic or other gear plugged in) to
either the radio or the computer, and no peripherals other than LCD
display, mouse, and keyboard.  I have a ground braid between the 5000A
ground lug and one of the computer case screws; the noise is the same
with or without the ground braid.  All the gear, including the Astron
power supply (not a switcher) is powered through a single UPS.

Any ideas what this might be about?  The fact that it's so much louder
at the fast sample rate is what has me confused.

Oh, and this is with 1.10.03 and the newly released firmware.

Thanks,

John

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Re: [Flexradio] anyone attend DCC this weekend?

[John Ackermann N8UR]

Hi Jim --

The DCC proceedings (paper version) will be available very shortly --
everyone at the conference got one, and I believe that they will be for
sale via TAPR and/or ARRL as soon as logistics allow.

More importantly, authors retain the copyright to their papers so they
are free to distribute them if they'd like, and we encourage them to
make their presentation slides freely available on line.

John


Jim Lux said the following on 10/01/2007 11:51 AM:
> At 08:14 AM 10/1/2007, Ken N9VV wrote:
>> If you attended the DCC Conference in CT, please send a short
>> report about how the DCC conference went this weekend. There seems
>> to have been no on-line broadcast of any of the speakers :-(
>>
>> [ ] how were Bob N4HY and Frank's AB2KT sessions?
>> [ ] was it well attended?
>> [ ] what surprises did you hear?
>> [ ] what innovations in digital ham radio did you see?
>> [ ] how soon can we purchase a hard copy of the proceedings?
> 
> 
> Can someone provide a summary of the new architecture which was going 
> to be revealed by Frank?  Based on previous posts by Frank, it won't 
> be published except in the proceedings, several months from now, 
> which aren't online, and aren't free, either.The software may be 
> F/OSS, but the documentation apparently isn't .
> 
> Or, does TAPR allow independent distribution of a conference paper?
> 
> 
> Jim, W6RMK

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Re: [Flexradio] N4HY + K5SDR defend Ham Radio at FCC

[John Ackermann N8UR]

I don't want to take *anything* away from what Bob and Gerald did on
this subject -- they were clearly strong voices for The Right Thing, but
I'd like the record to show that TAPR was also a voice in this effort.

TAPR was the only ham organization to file comments on the original
Cognitive Radio NPRM that challenged the FCC's proposals to limit fast
DAC chips and require hardware locks on ham SDR gear.  While AMSAT and
ARRL both filed comments, neither of them addressed those points.  We
made the argument that these restrictions would not only limit
experimentation, but they would also be unenforceable in practice.  The
net result would be an unnecessary reduction in our ability to advance
the state of the radio art.

I'm not a big horn-tooter, but TAPR has been focusing on SDR for a long
time now, and we'd like to think we've done some good :-).

73,
John

Ken N9VV said the following on 07/09/2007 06:55 PM:
> We Hams owe Bob N4HY and Gerald K5SDR a standing ovation at the next 
> public meeting! Bob and Gerald defended Ham Radio when the FCC rules for 
> SDR (Software Defined Radio) and CDR (Cognitive Defined Radio) were 
> being formulated. The Federal Register stands as a testament to the 
> power of their persuasive and well articulated arguments in front of 
> such a demanding audience. In the message below, Bob recounts some of 
> the encounter with the FCC.
> 
> Raise your glasses and join me in a hearty toast to Bob and Gerald for 
> their unselfish work on behalf of us all.
> 
> 
>  Original Message 
> Date: Mon, 09 Jul 2007 11:13:59 -0400
> From: Robert McGwier <[EMAIL PROTECTED]>
> 
> * High Performance Software Defined Radio Discussion List *
> 
> Gerald Youngblood and I went to the F.C.C. and we gave a talk and
> discussed their proposed rule making.  I believe you can see the impact
> we had throughout this document thought I don't claim we wrote any piece
> of it.  We pleaded for them to not get in the way of a successful move
> of amateur radio into the almost inevitable future where larger pieces
> of it were done digitally with software and cognitive radios.  We proved
> then, and we have continued to supply them and the ARRL CTO with
> information (ammunition) that shows amateur radio operators are doing
> INNOVATIVE development that is simply not being done elsewhere and much
> of it in SDR and CDR.  One of the best papers you can find anywhere on
> the foundations for CDR (the mathematical tools) is in QEX and written
> by Frank Brickle, AB2KT!
> 
> In the end,  they told us that if amateur radio SDR's did not self
> police and provide transmit frequency protection, and removal of
> completely automatic scanning outside of amateur bands that we were
> likely to face serious certification of a type that would not be
> affordable.  Now I know that faced with this,  we could come up with
> open source means of authentication that would pass, but the expense
> would be onerous.  I personally might personally be in serious trouble
> if I attempted to provide this.  In the end, I think we are simply going
> to have to live with small pieces of firmware at a minimum that prevent
> unauthorized use of amateur SDR equipment outside of the amateur bands.
> 
> Yes, we argued strongly that almost all amateur radio equipment could be
> easily modified to transmit out of band.  I offered to bring in an
> unmodified transceiver  and modify it in less than five minutes to show
> how easy it typically was.  I was told that I should not volunteer to
> commit a crime on federal property and that they were aware of this.
> The F.C.C. is responding to external pressure from all sorts of quarters
> from the White House to commercial entities like Cisco to NTIS, and the
> intelligence community as well as D.O.D.  The schizophrenic aspects of
> this are almost ludicrous.  You find one D.O.D. office wanting to
> support you, buy yours toys, help you help them,  and another wanting to
> kill the entire effort.  It is bewildering.
> 
> Given this order, which is now enforceable law since it was placed in
> the Federal Register, I expect more radio manufacturers to look at this
> order and jump into the SDR world more completely.
> 
> I think that, overall, with these competing pressures,  the F.C.C.
> struck a reasonable balance between the hysteria on the parts of some
> and the desires to reinvigorate amateur radio in particular but radio
> development in general in the U.S.  One only has to visit places like
> the Wireless group at V.P.I. and other places to realize that S.D.R. and
> C.D.R. are having a major impact on the new engineers and communications
> scientists being trained at many universities.
> 
> When Frank Brickle and I gave our S.D.R. course last fall, we had HALF
> of the entire senior electrical engineering class take the course and
> they did not know us from Adam's house cat and many were graduating, so
> it was a risk.  That was impressive, not to mention a fant

Re: [Flexradio] antenna Smith Chart can this be ad to program ?

[John Ackermann N8UR]

Jim Lux wrote:
> At 06:40 AM 6/29/2007, John Ackermann N8UR wrote:
>> Jim Lux wrote:
>>> At 07:23 PM 6/28/2007, Larry Phipps wrote:
>>
>>>>  My software is free, but not open source.
>>> And that appears to be the case for most (if not all) low cost VNA 
>>> solutions.
>>
>> The TAPR VNA (sold by Ten-Tec) software is open source and licensed 
>> under the GPL.  It's a Windows implementation but there is also a 
>> relatively complete Linux port (that could use some volunteer work to 
>> turn into a finished product).
> 
> I assume the "free VNA" bounty for a Linux version offered back in 2004 
> hasn't been collected 

Well, it got close enough to be collected -- but it didn't quite get 
there.  We had a working Linux system, but it never got sync'd with the 
latest version of the Windows code, and there had been some significant 
changes to sync.

I would love someone to pick up the challenge, and there is possibly a 
sucker, I mean a glorious volunteer, in the wings that I'm working to 
convince.

John

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Re: [Flexradio] antenna Smith Chart can this be ad to program ?

[John Ackermann N8UR]

Jim Lux wrote:
> At 06:40 AM 6/29/2007, John Ackermann N8UR wrote:
>> Jim Lux wrote:
>>> At 07:23 PM 6/28/2007, Larry Phipps wrote:
>>
>>>>  My software is free, but not open source.
>>> And that appears to be the case for most (if not all) low cost VNA 
>>> solutions.
>>
>> The TAPR VNA (sold by Ten-Tec) software is open source and licensed 
>> under the GPL.  It's a Windows implementation but there is also a 
>> relatively complete Linux port (that could use some volunteer work to 
>> turn into a finished product).
> 
> Thanks for the pointer.  Which Windows environment is it developed in? I 
> tried to load it up in VS2005 C++ and it brought up the conversion 
> utility..
> 
> Also, all the cal routines are just 1K stubs with a couple includes.
> 
> Maybe I'm looking in the wrong place? (VNAR3_HOST_source, both 1.6 and 
> 2.0) The InstrumentCal.cpp and Calibration.cpp both have 2003 dates.
> 
> Oho.. I see, they're buried in the .h and .res files..
> 
> 
> ANd, where is the Linux port?  The windows one is awfully tightly 
> coupled between UI and processing (e.g. the actual cal work is attached 
> to click methods for form controls), and before trying to separate them 
> out, maybe someone has already done that.  (My own style is to have the 
> click method just invoke a UI independent routine somewhere else, so the 
> numerical heavy lifting isn't tied to the UI)

I didn't write the code, so I don't have deep knowledge of the bits and 
pieces... I know it uses .NET, though.

The Linux port may not be uploaded there; I'll check when I have a 
chance this weekend and if it's not there upload the latest. 
Unfortunately, the porting project died about 90% of the way through, 
and it's now a couple of software revs behind.

> I suppose there's some mailing list around which has all this. I'll have 
> to google for it..

Check https://lists.tapr.org/mailman/listinfo/vna

John


> 
> 
>> The software and documentation is available at 
>> http://www.tapr.org/software_library.php?dir=/pub/n5eg
> 
> 
> Not much software documentation there.. just hardware and software 
> installation/use

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Re: [Flexradio] antenna Smith Chart can this be ad to program ?

[John Ackermann N8UR]

Jim Lux wrote:
> At 07:23 PM 6/28/2007, Larry Phipps wrote:

>>  My software is free, but not open source.
> 
> And that appears to be the case for most (if not all) low cost VNA solutions.

The TAPR VNA (sold by Ten-Tec) software is open source and licensed 
under the GPL.  It's a Windows implementation but there is also a 
relatively complete Linux port (that could use some volunteer work to 
turn into a finished product).

The software and documentation is available at 
http://www.tapr.org/software_library.php?dir=/pub/n5eg

John

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Re: [Flexradio] [OT] LNA VHF preamps

[John Ackermann N8UR]

Tim Ellison said the following on 06/16/2007 04:48 PM:

> One mfg. claims that the new "very low noise" dual gate MOS FETs have a
> better noise figure than the GaAs FETs.  I have always heard that the
> GaAs FETs were the way to go for the best noise figure, so I am confused
> from the marketing hype.
> 
> I am looking to get a non-mast mounted preamp for 6 meters.  I have a
> few transceivers that cover 6 meters, but are not the best for weak
> signal work and need a little help. This could be a receive only device,
> as that would be it's initial function, but I am not excluding mast
> mounted ones either.
> 
> If anyone want to make a recommendation for a particular mfg. or kit,
> that would be appreciated too.

Hi Tim --

Remember that the noise figure of the amp only matters if it's higher
than the background noise.  So, at 6M where other noise is still
significant, you don't need to strive for a <1dB noise figure (even
though it's pretty easy to obtain).  Similarly, mast mounting doesn't
gain you much unless the feedline is very long, unlike at higher
frequencies where getting the gain ahead of the coax loss becomes very
important.

For what it's worth, I've always liked Advanced Receiver Research
(www.advancedreceiver.com) preamps.  They have a wide range available.

John

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Re: [Flexradio] Reference Oscillator

[John Ackermann N8UR]

To follow up my earlier post, a byproduct of the phase noise
measurements I did was frequency stability during the 5 minute
transmission period.  Those results are at
http://www.febo.com/pages/hf_phase_noise/freq.html .

Note that my internal oscillator does NOT have the new thermistor ECO
applied, so rigs with that change might do better.  On the other hand,
the rig had been running for 24 hours in a stable environment before the
test began.

73,
John


Phil LaMarche said the following on 06/02/2007 12:39 PM:
> Asking for an opinion.  Instead of using a OCXO, just leave the SDR1K
> powered up 24/7.  Isn't the stability just as good?  OR, is even tighter
> better?
> 
> Phil 
> 
> 
>  Philip LaMarche
> LaMarche Enterprises, Inc.
> www.instantgourmetspices.com
> www.W9DVM.com
> 727-944-3226
> 800-395-7795 pin 02
> FAX 727-937-8834
> NASFT # 30210
> W9DVM
> 
> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Neal Campbell K3NC
> Sent: Saturday, June 02, 2007 12:26 PM
> To: Ken
> Cc: FlexRadio@flex-radio.biz
> Subject: Re: [Flexradio] Reference Oscillator
> 
> I put one of Alan's boards in my SDR1K and can vouch its amazing!
> 
> Neal Campbell K3NC
> [EMAIL PROTECTED]
> 
> telnet to our DX Spotting clusters at: dxc.k3nc.com, ports 12001 and 23
> 
> "Devoted to Dogs: How to be your dog's best owner"
> Great Dog Book  at www.abrohamneal.com
> 
> 
> 
> On Jun 2, 2007, at 11:30 AM, Ken wrote:
> 
>> One of the most successful is the OCXO mod for the SDR-1000 that Alan 
>> K2WS offers as a kit:  http://www.k2ws.us/K2WS-OCXO.html he has an 
>> installation manual as well:
>> http://www.k2ws.us/Images/K2WS/OXCO-Installation-Guide.pdf
>>
>> de ken n9vv
>> Frank Mayer wrote:
>>> Any ideas on a external reference TCXO?  Frequency, etc.  I have seen 
>>> some Wenzel units on the internet.
>>> Frank  WA3JBT
>>>
>>>
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[Flexradio] Another SDR-1000 Phase Noise Measurement

[John Ackermann N8UR]

A while ago I did some testing on the SDR-1000 to see whether an
external 10 MHz reference oscillator gave worse phase noise performance
than the standard 200 MHz oscillator.

Then, John, K20X, did some excellent work (see
http://www.exothink.com/SDR/SDRPN/index.htm)

I've now done some follow-up measurements that build on John's work.
Where he measured the noise of the DDS system directly, this time I
measured the noise at the transceiver output so that the entire system
-- including sound card (a Delta 44) -- was measured.  I measured the
SDR-1000 when driven by the standard internal oscillator, a fairly noisy
Marconi signal generator, an extremely quiet Wenzel Ultra Low Noise
oscillator, and an HP Z3801A GPS disciplined oscillator.

I also measured a couple of other HF rigs that I had handy to get some
idea of how the SDR1000 compared to other transceivers.

The results are at http://www.febo.com/pages/hf_phase_noise/index.html

I haven't done a lot of deep analysis yet, but here are a few observations:

1.  The SDR-1000 with standard oscillator performs about the same as the
other HF rigs I tested; it was a bit worse than the other modern rigs
below 10 Hz offset, quite a bit better than them between 10 Hz and
10kHz, and somewhat worse at distant offsets.

2.  The SDR-1000 has many spurs in the range of about 60Hz to 10kHz
offset.  I suspect these come from the PC-mounted sound card.  They are
all at least 60dB down from the carrier, so most likely wouldn't be
noticed on the air.  Using an external sound card like the Edirol would
probably reduce computer-generated spurs, and I'll bet the new SDR-5000
will be much better in this regard because the analog stuff is all
inside the box.

3.  The results with various 10MHz reference oscillators compared to the
standard 200 MHz oscillator were surprising, but make sense if the DDS
chip incorporates a PLL:

(a) at close offsets -- say, 1 to 10 Hz -- a good external reference
shows better phase noise than the internal reference.

(b)  at mid offsets -- say, 100 Hz to 10 kHz -- there's not much
difference between any decent oscillator and the internal reference (the
Marconi generator is much worse, but that's why I included it!).

(c) at distant offsets -- beyond 10kHz -- two things happen:  first, the
external references -- even the Marconi -- are just about the same, and
second, the internal reference is almost 10dB better at 30 kHz.  The
fact that all the external references converge indicates that we're
seeing the loop filter bandwidth of the PLL that the DDS chip uses to
multiply the external reference.  The internal 200 MHz crystal
oscillator doesn't use this PLL, so it can provide better performance.

But... there is something going on from about 30 kHz that causes the
noise to increase, no matter what the reference.   At 100 kHz, the
internal reference has only a couple of dB advantage over any of the
external references.  Unfortunately, my measurement system only looks
out to 100 kHz, so I can't tell what happens further away.  I see
somewhat similar results on some of K2OX's DDS measurements; his
measurements indicate that the noise starts going down again at perhaps
300 kHz offset.

73,
John

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Re: [Flexradio] Disk-less Flex Radio

[John Ackermann N8UR]

RAM is cheap.  Use a big RAMdisk and load it, or at least the OS 
elements that need to be on a R/W filesystem, from USB or Flash media at 
boot.

With a couple of gigs of RAM not being unreasonable today, I'd think you 
could make this work using a stripped down version of Windows something 
or other.

It's a very different application profile, but embedded systems do this 
under FreeBSD and Linux all the time, with much smaller RAM footprints 
(my Soekris net4501 NTP servers boot from a CF image and run with a 
RAMdisk of less than 32MB).

John


Larry W8ER wrote:
> Neal .. I think the point is being missed. USB hard disks. Not flash 
> cards on IDE adapters nor solid state drives on IDE interfaces etc. I 
> can't imagine how they could block booting from any IDE device 
> especially one that emulates an IDE hard drive!
> 
> --Larry W8ER
> 
> 
> 
> Neal Campbell K3NC wrote:
>> I do think its possible.
>>
>> If you purchase 2 IDE adapters for flash cards, I believe you should 
>> be able to install windows on one and use the other for paging and 
>> powersdr. I am not saying I would want to do this, but I cannot see 
>> any limitations that would refuse it. My windows folder is 2GB and you 
>> can certainly buy bigger flash cards than that.
>>
>> I have had USB disks interfere with WinXP booting before so I know 
>> that at least some bios will look there for bootable media. I think if 
>> you turn off legacy USB support this will not happen but again, if you 
>> use IDE adapters (I paid 3 bucks for mine and it plugs directly into 
>> the IDE channel plug on the motherboard).
>>
>> Again, not sure why I would want to do this but I think its possible 
>> to do so.
>>
>> Neal Campbell K3NC
>> [EMAIL PROTECTED] 
>>
>> telnet to our DX Spotting clusters at: dxc.k3nc.com, ports 12001 and 23
>>
>> "Devoted to Dogs: How to be your dog's best owner" 
>> Great Dog Book  at www.abrohamneal.com 
>>
>>
>>
>> On May 7, 2007, at 4:47 PM, Larry W8ER wrote:
>>
>>> See reply below:
>>>
>>> k5nwa wrote:
 Are you running the SDR-1000 software on a company computer? Bad boy!

>>> Silly question! No.
 If you plug in a USB stick then turn on the PC with a XP install disk 
 in the CD ROM you have the option of installing XP on the USB stick. 

>>> WRONG. It will not install any code into a boot sector. It will err out! 
>>> Tried it .. been there .. done that.
>>>
>>> snip
>>>
 ...You can also install Linux 
 in a USB stick.
 Check out Puppy Linux, it's specifically made to run on a CD or a USB 

 stick and it runs really fast.

>>> and what version of PowerSDR do I run under Puppy Linux Cecil?
 I setup an alternative profile, and turned off everything under the 
 sun that was not needed, I disabled all networking services, all 
 anti-virus, firewall, help, updating, remote access, and any service 
 not needed for use in running the SDR-1000. It went from 50% spiking 
 to 70% to less than 10% with no spikes in utilization. Because it's a 
 separate profile when I boot I have a choice of picking it or the 
 normal profile. XP is also using less that 64MB of RAM while in that 
 configuration.

>>>  Cecil ... how do you set up such an alternative profile under XP 
>>> without booting XP from a hard drive first? I thought the idea was to 
>>> boot the OS and run PowerSDR from a USB memory stick?
>>>
>>> I contend that you cannot boot an operating system that will run 
>>> PowerSDR from a USB memory stick. Am I wrong?
>>>
>>> --Larry W8ER
>>>
>>>
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Re: [Flexradio] [KB] FLEX-5000 FAQ has been updated

[John Ackermann N8UR]

Jim Lux said the following on 04/16/2007 06:23 PM:

> I'm sure the flex folk have been furiously formulating a response to 
> all of our speculation, little realizing what a firestorm an offhand 
> FAQ might trigger.
> 
> I just throw some more gasoline on the fire, out of sheer 
> cussedness... reverse engineering the firmware would be illegal in 
> the United States because of the DMCA anti-circumvention rules.

I wouldn't leap to that conclusion.  The anti-circumvention rules apply
only to attempts to work around "an effective means of content
protection" and a couple of court cases have recently held that
encryption or locks that aren't related to a copyrightable content
stream can't rely on the DMCA.*

John

* One case involved a Lexmark printer that had a CPU in the toner
cartridge; if the CPU didn't handshake with the printer, it wouldn't
work.  The court held that reverse engineering that interface didn't
violate the DMCA.  The second case involved a universal garage door
opener remote control that reverse engineered a "rolling code"
algorithm.  The court there also held that breaing that algorithm didn't
violate the DMCA.  The main reasoning in both cases is that the
mechanisms weren't protecting copyrightable material (like a movie or
music) and therefore the DMCA didn't apply.

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Re: [Flexradio] 10 MHz GPS Disciplined Master Oscillator

[John Ackermann N8UR]

Jim Lux said the following on 04/11/2007 07:52 PM:

> If you multiply it up to 200 MHz for the SDR1K, the noise would 
> increase by 20logN, or 26 dB.. That would make the noise at 1kHz out 
> about -124dBc/Hz.  The VF161 in the radio already has a floor of 
> about -125 dBc/Hz at 1kHz out, so it's in the same ballpark.  With 
> the huge advantage that the frequency is much more stable...

We've talked about this in the past, but I don't know if there was ever
a "definitive" answer supplied:

Multiplying from 10 up to 200 MHz multiplies the phase noise by 26 dB.
However, the DDS output isn't at 200 MHz, but in the HF range.  Does
phase noise of the DDS output then divide by the ratio of output
frequency to clock speed?

73,
John

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Re: [Flexradio] external OCXO, silly question

[John Ackermann N8UR]

The 50 ohm termination does two things:

1.  It terminates the coax from the oscillator so you reduce ringing and
the possibility of increased jitter that results, and

2.  The maximum input voltage that the DDS can accept is fairly low, and
an unloaded clock signal can fairly easily exceed that level.  The load
helps ensure the voltage will be under that limit.

John


Jean-marc BORD said the following on 03/24/2007 07:02 AM:
> Hi,
> 
> Apologize, I do have a rather silly question. I am in the process to 
> connect an external OCXO to the DDS board and saw that the external XO 
> connection kit handle a 50ohm resistor to 'load' the input of the DDS 
> clock.
> Is it mandatory ? related to the fact that the DDS clock input Z is >> 
> 50ohm ?.
> 
> Best regards
> Jean-marc F1HDI
> 
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Re: [Flexradio] Spur on AM

[John Ackermann N8UR]

Which transformers did you find with that bandwidth?  I bought some of 
the Stacor ones that had been recommended earlier, and they have 
signicant roll-off above something like 10kHz.

John


kd5nwa wrote:
> You need a transformer with higher bandwidth and better phase 
> response, you can buy some at Mouser for $15 that are flat from 200Hz 
> to 100KHz +- .1 dB, but it's just a transformer, there is no case, 
> connectors or anything. I have some links at home for some commercial 
> isolation transformers that are better than the RS ones but they cost 
> a lot more.
> 
> At 09:57 AM 1/23/2007, you wrote:
>> I just made a few more measurements using my Delta 44 and some of my test
>> equipment.  Adding in the ground-loop isolator to the Line-In path has the
>> following effects:
>>
>> Positive:
>>
>> 1.  Noticably reduces the IF "hump".
>> 2.  "Flattens" the display (w/o the isolator, I see a bit of rolloff towards
>> the display edges when in 0.5x zoom mode.
>>
>> Negative:
>>
>> 1.  Image rejection worsens at the display edges.  That is, if a strong
>> signal is in the receive audio passband (I used a -40 dBm signal) and you
>> null its image down to the noise-floor, if you then shift the frequency of
>> the received signal (but not the receiver's VFO-A frequency), you'll see the
>> image begin to reappear.  If the signal is moved in frequency such that the
>> image is at the edge of the display (again, in 0.5x zoom mode), it appears
>> to me that the image rejection is about 10 dB worse *with* the line
>> isolator.  In other words, it's in the mid to high 30's (of dBs) instead of
>> the mid 40's.  (Note, though, that in either case, the image can be nulled
>> down to the noise).
>>
>> I'm not sure that the positives outweigh the negatives, but it raises some
>> questions:
>>
>> 1.  Can an "isolator" be designed, in hardware, to maximize the positives
>> and minimize the negative?
>> 2.  Could a filter be designed so that, when it's convolved with the input
>> signal, we maximize image rejection across the whole display, and not just
>> at the frequency for which the image is nulled.  That is, can the "bowl"
>> shaped response to image rejection (when viewed across the entire display)
>> be flattened?  If so, how could this be done.  (And what's the plan
>> regarding the use of the pulse generator that's in the hardware?)
>>
>> - Jeff, K6JCA
>>
> 
> 
> Cecil Bayona
> KD5NWA
> www.qrpradio.com www.hpsdr.com
> 
> 'Never argue with an idiot. They drag you down to their level then 
> beat you with experience.'  
> 
> 
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Re: [Flexradio] I decided to be a guinea pig Linux 101

[John Ackermann N8UR]

Doug Bade said the following on 01/03/2007 10:39 AM:

> I worked my way down a list I found through google with a step by 
> step listing to get dttsp running... and made it down to installing 
> "Jack" and was unable to proceed...
> 
> Apt-get was unable to find this repositorythat was all in a 
> couple hours last night

That one is a gotcha -- in Ubuntu (and I presume other Debian-based
distros), the Jack daemon is in the package "jackd" and the GUI
interface tool is in "qjackctl".  There is also a library package and
possibly other dependencies, but doing "apt-get install" on those two
will probably get you everything you need.

There really should be a "jack" meta-package that will install the
various sub-packages to make a useful installation, but apparently no
one has gotten around to that yet.  Another challenge is that, as cool a
tool as Jack is, its documentation (for mere mortals, anyway) seems to
be largely non-existent.

73,
John

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Re: [Flexradio] Linux, any chance of a knoppix like setup?

[John Ackermann N8UR]

Count me in on the groundswell...

John


Frank Brickle said the following on 01/01/2007 02:56 PM:
> If people want a consumer-oriented Linux version, there has to be
> a groundswell of popular support for it. Otherwise the individual
> Linux developers are going to continue to write to suit
> themselves, and that development is, for now, aimed almost
> exclusively at experimenters.


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Re: [Flexradio] Windows highway robbery

[John Ackermann N8UR]

Alan NV8A said the following on 10/20/2006 06:27 AM:
 http://blogs.zdnet.com/Bott/?p=156&tag=nl.e622

> While I am no fan of Micro$oft and use its products as little as 
> possible, I read a discussion of this point somewhere else, and someone 
> suggested that the intention was to prohibit a person from transferring 
> the software to several computers before deleting it from the original 
> machine.
> 
> It says that it may be transferred only to ONE computer, *not* that it 
> may be transferred only ONCE.

Unfortunately, that's not true.  The license for Vista "Home Basic",
"Home Premium", and "Ultimate" has a number of provisions that limit reuse.

1.  You are required to assign the license to one physical hardware
system.  (Section 2)

2.  "The first user of the software may reassign the license to another
device one time.  If you reassign the license, that other device becomes
the 'licensed device'." (Section 15)

3.  "The first user of the software may make a one time transfer of the
software, and this agreement, directly to a third party.  The first user
must uninstall the software before transferring it separately from the
device.  The first user may not retain any copies.  (Section 16(a))

4.  "Before any permitted transfer, the other party must agree that this
agreement applies to the transfer and use of the software.  The transfer
must include the proof of license."

So, the *first user* may reassign the software to another machine
*once*.  And the first user can transfer the license (i.e., if you sell
the computer with Vista installed), but that second user has no right to
further transfer it.  So, if you buy a used machine with Vista
installed, you can't resell the machine without taking the OS off.

73,
John

PS -- by way of background, I teach a course in IP licensing at our
local law school, and I just spent our last class going through the
Vista agreement with my class.  It wasn't a pleasant experience. :-)

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Re: [Flexradio] Looking fo Rubidium standard

[John Ackermann N8UR]

Edward J White wrote:
> Hi Gang:
> I am looking for a Rubidium frequency standard to run the SDR-1000 
> oscillator. I know others have done this to run 10 GHz. What is the best 
> price and make model where and where should I be looking for one(I know the E 
> place).
> Ed 
> WA3BZT

You may want to be careful about using one of the small Rb standards 
(like the Efratom FRS or FRK) for this application.  They tend to have 
fairly bad phase noise because the reference frequency is FM'd as part 
of the lock system.  An HP5065A Rb doesn't have this problem, but is a 
much bigger and more expensive beast.

73,
John

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Re: [Flexradio] Audio Amp for receive

[John Ackermann N8UR]

I recently built a 3 watt stereo amp from Carl's Electronics 
(http://www.electronickits.com).  For $17.95, it's a very good deal.

I put it in a simple metal enclosure and got nice audio, but am still 
having some RF issues.  I'm now planning to repackage it in a Hammond 
box with bypassing on the I/O and -- I suspect this may be key -- 
transformer isolation on the inputs.

John


Radio Station W5AMI wrote:
> I wanted to ask the list members for a recommendation on an outboard
> audio amp to drive a pair of nice speakers that has proven to be
> resistant to RFI before I went out and bought something.  I have
> considered building a tube amp using a pair of 6V6's, or 6AQ5's in
> push-pull output, but after pricing some good inter-stage and P-P
> output xfmr's, I've had second thoughts.
> 
> I really want something to give me the freq. response the SDR1K can
> deliver when I choose to listen in that mode.
> 
> Good speaker suggestions are also very welcome.  My main concern is RF
> getting into the amp if I run the legal limit power.  Any suggestions
> or recommendations will be much appreciated.
> 
> By the way, I'm using the Delta 44 on my Flex, but I figure most any
> consumer or pro level audio amp would work fine with the output on the
> D-44 with proper adustment from -10 to +4 dB in the M-Audio console.
> 
> TIA
> Brian / w5ami
> 


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Re: [Flexradio] Notebook computers

[John Ackermann N8UR]

Robert McGwier wrote:
> My 2.4 GHz Sony Vaio is solid and fast.  I need to clean it out because 
> the fan is always on high but it is solid.  I am reluctant to give it up 
> for one of these throttling monsters that you can't choke off from 
> throttle.  My Dell laptop which runs Linux, has the throttle problem.  
> It is great at 2.2 GHz but throttles back to 900 Mhz off the mains and 
> will not go the other way, even if power is reapplied.  Gr.  So I 
> understand that feeling.

I had a Vaio several years ago, and it was an excellent computer. 
HOWEVER, it is impossible to get service information or parts from Sony. 
  I needed to replace the hard disk and the only service info I could 
find on the Sony website was where to send it.  I had the joy of 
figuring out how to open up the case (no easy task) without any 
documentation.

Contrast that with the Thinkpad where IBM had full service manuals 
online, complete parts lists, all drivers individually available for 
download, and a very efficient/helpful parts ordering system.  Thanks to 
that, I've replaced keyboards, power supply modules, etc. on a bunch of 
Thinkpads over the years.  I don't know if that's changed since Lenovo, 
though.

John

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[Flexradio] Solved: Looking for speaker amplifier

[John Ackermann N8UR]

A couple of weeks ago I asked about amplifiers to allow the use of a
standard communications speaker with the SDR-1000.  I found a good solution.

There's a company called Carl's Electronics (www.electronickits.com)
that has a whole bunch of simple kits.

One of them is a 3 watt stereo amp
(http://www.electronickits.com/kit/complete/ampl/ck705.htm) that costs
$17.95.  It uses a Rohm monolithic amp module and maybe a dozen discrete
components.  It took about 20 minutes to build (and another 6 hours to
get it packaged and integrated into my shack, but that's not the kit's
fault...) and works really well.

The main challenge is that the amp has no input gain control, and the
Delta 44 overdrove it terribly.  I put a couple of 2.5k trimpots on a
bit of perfboard, and with those was able to tame the level -- though
I'm running the pots cracked just a hair above the minimum.

I wanted to bring in sidetone from my ancient AEA MorseMatic keyer, and
did that by feeding the sidetone through a pair of 4.7k resistors (one
for each channel) to the inputs of the amp.  Since the sidetone is mono,
the tops of the resistors are tied together and the sidetone is fed in
there.  Coupling through the resistors causes some crosstalk, but the
channel separation for binaural mode is still OK.

By the way -- while futzing around I remembered a nice trick for
balancing the channel gain.  Feed a common signal into both channels,
and hook a scope in XY mode to the speaker outputs.  Set one channel for
the volume level you want, then set the other channel for a 45 degree
diagonal line on the scope.  Voila!

73,
John

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[Flexradio] Field Day CW setup help

[John Ackermann N8UR]

Hi --

I know this is a question I should be able to answer myself, but due to
work commitments I'm very limited for time between now and Field Day...

Even though I have one of the first handfuls of SDR-1000s Gerald ever
shipped, I've mainly used it in "farting around" mode and haven't done
much serious operating.  This year, I've committed to take it out to
Field Day and show what it can do.

The problem is that I operate 99% CW at Field Day.  And since FD is
about the only time I ever get on the air anymore, I've always done it
the old-fashioned way -- with paddles and paper logs.

If I'm gonna use an SDR, I suppose I might consider updating my
operating procedure at the same time.  So, I want to consider some
combination of keyboard CW and computerized logging.

I'd really appreciate it if someone who's been through the various
considerations for contest CW operation with the SDR-1000 would be
willing to help me (offline is OK to avoid boring everyone else) come up
with a workable configuration for both external keyer and keyboard
operation, ideally with integrated logging.

Thanks much!

73,
John

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Re: [Flexradio] Speaker Amplifier?

[John Ackermann N8UR]

Hi Peter --

Not sure I follow... are you talking about ripping the amplifier board
out of a speaker, or a separate box that's part of the system?  I've
only seen PC speakers with the amp built in.

Thanks!

John


petervn said the following on 05/27/2006 11:13 AM:
> Hi John
> I use an amplifier from a PC speakerset, 
> there are lots of them around in secondhand shops
> some with 230 / 127 volt power others with 12V DC
> maybe you can try that.
> good luck peter pa0pvn
>  
> 
>   -Oorspronkelijk bericht- 
>   Van: [EMAIL PROTECTED] namens John Ackermann N8UR 
>   Verzonden: za 27-5-2006 16:19 
>   Aan: FlexRadio@flex-radio.biz 
>   CC: 
>   Onderwerp: [Flexradio] Speaker Amplifier?
>   
>   
> 
>   I'm trying to tie my SDR-1000 into the rest of my station gear, and
>   would like to use my NCS "Multi-Switcher" to select audio paths.  I have
>   a pair of unamplified communications speakers, and therefore need to
>   come up with an amplifier for the SDR-1000 audio output.
>   
>   I'm sure I can build something up if I need to, but to avoid that hassle
>   -- can anyone recommend a simple audio amplifier with a couple of watts
>   output?  Ideally, I'd like a stereo unit so I can play with binaural
>   audio, etc.  Small size would be good.
>   
>   Thanks and 73,
>   John
>   
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>   
> 


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[Flexradio] Speaker Amplifier?

[John Ackermann N8UR]

I'm trying to tie my SDR-1000 into the rest of my station gear, and
would like to use my NCS "Multi-Switcher" to select audio paths.  I have
a pair of unamplified communications speakers, and therefore need to
come up with an amplifier for the SDR-1000 audio output.

I'm sure I can build something up if I need to, but to avoid that hassle
-- can anyone recommend a simple audio amplifier with a couple of watts
output?  Ideally, I'd like a stereo unit so I can play with binaural
audio, etc.  Small size would be good.

Thanks and 73,
John

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Re: [Flexradio] Searchable archieves

[John Ackermann N8UR]

Not speaking for the Flex-Radio team, but as someone who runs a Mailman
list server...

Unfortunately, Mailman doesn't support searchable archives out of the
box.  There are ways to do it (which the hpsdr folks must have figured
out) but it takes patching Mailman and using additional software.  The
Mailman web site points you toward several ways of doing it, but doesn't
give an official "blessed" solution.  The patching requirement is a real
concern, because that makes automated updates for, e.g., security
issues, more difficult to manage.

I've looked into it for the tapr.org and febo.com mailing list archives
(which both use Mailman) and unfortunately it takes quite a bit more
than just "flipping it on."

73,
John

[EMAIL PROTECTED] said the following on 04/29/2006 11:33 AM:
> Yes, I agree w/ Lee here.
> 
> I have had may Flex on the bench for abt 36 hrs now.  It was just delivered
> to me on Thurs, and I have many questions that I know have been asked and
> answered a million times. I would LOVE to be able to search the archive as
> use them as a knowledge-base.
> 
> I am sure the "searchable" feature is just a simple switch in the pipermail
> software.
> 
> Someone needs to "FLIP IT ON !!!"
> 
> Best Regards,  -Dan K6KDK
> 
> PS: So far the report the report on my new Flex is that "The Flex Sure Makes
> Me Happy!"  (This is a not-so-very inside joke from those of you that follow
> the TT reflector, I am sure Lee will get a chuckle out of it anyway...)
> 
> 
> - Original Message -
> From: "Lee A Crocker" <[EMAIL PROTECTED]>
> To: 
> Sent: Saturday, April 29, 2006 8:14 AM
> Subject: [Flexradio] Searchable archieves
> 
> 
> 
>>How come the flex-radio archieves are not set up like
>>this sites archieves?
>>
>>http://lists.hpsdr.org/pipermail/hpsdr-hpsdr.org/
>>
>>Note these archieves are searchable.  These people are
>>certainly flex radio friendly, it would seem they
>>might be willing to share a little advice on how to do
>>this.

Re: [Flexradio] How to wire this up?

[John Ackermann N8UR]

Jim Lux said the following on 03/19/2006 03:01 PM:
> At 11:34 AM 3/19/2006, Neal Campbell wrote:
> 
>>Hi guys
>>
>>
>>
>>I just bought a Bliley NV26R891 voltage controlled  ovenized  100 Mhz
>>crystal oscillator. Should it be possible to use it for external frequency
>>standard for the SDR-1000? Any ideas on how to wire it up?
> 
> 
> Check out the external frequency reference ECO on the Flex 
> website.  Basically, you pull the existing 200 MHz oscillator out and feed 
> your 100 MHz signal in.  You need to tell PowerSDR that you're doing this, 
> so it can turn on the internal frequency multiplier, et.c

There's a gotcha -- the DDS chip has a multiplier range of 4 to 20, so
in theory 100MHz doesn't work.  You can use either 50MHz, or 200MHz.
However, I had some success when I tried using a 100MHz source some time
ago before I knew of the multiplier limitation.  i.e., I got a signal
out but I don't know what negative characteristics it might have had.

John

Re: [Flexradio] VF-161, TCXO, OCXO Oscillator and DDS Phase Noise

[John Ackermann N8UR]

Great work, John!!!

I'm really looking forward to the actual SDR-1000 measurements to see
whether the noise multiplication from the on-chip multiplier is
according to theory or if there are other factors involved beyond simple
scaling.

I haven't had a chance yet, but will also compare your measurements to
the ones I took over Xmas using the same Agilent box.

73,
John


[EMAIL PROTECTED] said the following on 02/04/2006 12:22 PM:
> Hello Enthusiasts,
> 
> I've made several phase noise measurements and posted them at 
> www.exothink.com/SDR.  The first page shows plots comparing 
> different quality oscillators suitable for use in the SDR1000.
> The second page contains several measurements at the DDS output.
> 
> These graphs were generated in Excel so that different measurements
> could be plotted on the same graph.  I also have a couple dozen
> virgin instrument screen dumps that I'll add at a later time.
> 
> Several measurements have also been made on the SDR1000 to provide 
> insight on how the phase noise LO performance relates to real world 
> receiver performance.  I'll let you know when I get these posted.

Re: [Flexradio] Beginners - Experts - Terminology and stuff

[John Ackermann N8UR]

Hi Gerald --

My $0.02:

First, I think the mailing list(s) are a huge improvement over the 
forums.  It's an issue of push vs. pull -- I'm much more likely to read 
an email that ends up in my inbox than I am to remember to go to the 
forum and work my way through the postings.  Forums are great for 
long-term availability of info, but (IMHO) they are a horrible approach 
to near-real-time discussion (and, for me at least, the email interface 
is a lot more efficient way to read and reply; there are far fewer 
clicks involved).


Second, I think you might consider three reflectors:  flex-radio for 
general, non-technical discussion, flex-radio-beta for discussion of 
beta bugs and features, and flex-radio-futures for the Xylo/FPGA/Linux 
etc., etc. conversations.


If you only want two lists, I'd separate out the beta discussions. 
Moving discussion of beta version problems/requests/etc. to its own list 
would reduce both traffic *and* "is this a finished product or not" 
confusion on the main list.


73,
John


Gerald Youngblood wrote:

Eric E.,
 
Thanks for some very succinct explanations.  
 
Let me put forth a couple of concerns we have about how to best use the
reflector and forum resources.  
 
Due to the nature of a "software" radio, we will always be releasing new

beta software that will have bugs.  The discussion on this reflector of
"beta bugs" has been a huge source of confusion to new and potential
customers.  It gives the impression that the radio is unstable or
unfinished.  Five years from now this will still be an issue unless you the
users and we the manufacturer have run out of good ideas.  Somehow I doubt
that.  Our wish list is longer today than it was three years ago when we
shipped serial number uno.  We have thought of creating a "Beta and
Experimental Reflector" to separate the discussion of the new and
experimental  stuff from that of the officially released software.  It could
potentially make it less intimidating to the new user and the potential
customer.  
 
I agree that splitting the reflector could dilute the resources who help the

new user.  The email reflector has been a big improvement in some ways over
the Forum because it is much more real time.  It has been a great help to
FlexRadio because many of you know more than we do about specific
applications of the radio.  The Forum may actually be better from a FAQ
standpoint but it can become out of date very quickly as the software
evolves.  Since the reflector started, the traffic on the website Forum has
gone down dramatically.  This indicates to me that the immediacy of the
reflector meets the needs of the larger population better than the Forum.
However, the Forum has the ability to organize archive topics in a much more
user friendly way than the reflector.  It also has the capability to imbed
easily graphics.
 
With that said, I am very interested in hearing your thoughts on how we can

better serve the diverse needs of the neophyte to the advanced experimenter.
All are important the hobby of amateur radio.
 
I would like to know what you think about the following:
 
1) Should we create a separate reflector for "Beta Software and Experimental

Topics?"  The proposal would keep this reflector with a general interest and
support focus.
2) How can we better utilize the website Forum, which now has fairly low
traffic?  Would it help to have volunteer moderators who monitor the Forum
to make sure people get their questions answered?
3) How do we address the misperception of product instability caused by the
never ending improvements that will come in the software over the years?
4) How do we make sure that new users and potential users feel comfortable
posting their questions?  How do we make sure they get the answers they
need?
 
Your comments are welcome.
 
73,

Gerald
 
Gerald Youngblood, K5SDR

President
FlexRadio Systems
8900 Marybank Drive
Austin, TX 78750
Ph: 512-250-8595
Email: [EMAIL PROTECTED]
Web: www.flex-radio.com  
 



  _  


From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison
Sent: Thursday, February 02, 2006 11:19 PM
To: Flexradio@flex-radio.biz
Subject: [Flexradio] Beginners - Experts - Terminology and stuff



Folks

 


A Reflector member contributed a PM  suggesting that I clarify some of the
terms the I, and others have been using on the Reflector since the acronyms
can be daunting to recent members reading. I find this a very reasonable
request.

 


I'll start with that:

 


FPGA (Field Programmable Gate Array)

An integrated circuit which is essentially a "hardware etch-a-sketch". About
4 manufacturers make them. You actually write a program with tools offered
by the manufacturer and create your own customized integrated circuit. It
can be just about anything, from a microprocessor to a high speed counter,
to a light switch, when you press the button it lights the light. Price
range is $10 to $1800. It is an order of magnitude beyond a

Re: [Flexradio] 160 Meter Filter?

[John Ackermann N8UR]

For what it's worth, I have had very good luck with high-pass filters by 
I.C.E. which I think are sold through Array Solutions.  They have two 
versions -- one with a cutoff just below 160M, and one with a cutoff 
just below 80M.  They handle 100 watts so can be put in the antenna line 
after the rig.


I have very strong local BCB here (like -3dBm at the bottom of the coax) 
and these filters are needed for use *anywhere* on HF.  They make a huge 
difference.  In my case, since I don't have an antenna for 160, I use 
the 80M version which has much better rejection.


73,
John N8UR
[EMAIL PROTECTED]

Larry W8ER wrote:

Jeff et all, the filter that is supplied with a new Flex Radio is a low pass filter. It does not 
attenuate broadcast band signals. There is a problem with the SDR-1000 (many other radios too) when 
you live in an area that has broadcast stations in the area. Broadcast station images appear in the 
160 meter band. The Flex that I just sold was sent back to Flex and had a "bandpass" 
filter installed in place of the low pass front end filter that is standard. 160 meter operation is 
flawless with this mod! If you normally listen to broadcast stations however, you will not be able 
to do that after the new filter is installed. I am sure that Gerald or Eric can supply the 
information on what is needed to make this change. It is a couple of new inductors and caps and can 
be done by the owner without shipping it back if you are handy with the "iron". If all 
you have is a blowtorch however ... you might want to send it back!

--Larry W8ER 
  - Original Message - 
  From: Jeff Anderson 
  To: Flex Reflector 
  Sent: Thursday, January 26, 2006 2:05 PM

  Subject: [Flexradio] 160 Meter Filter?


  Does anyone know what 160 meter filter Larry is referring to?  I've noticed that I have 
horrible Broadcast Band images appearing throughout 160 meters, and I was going to roll 
my own filter, but...is there an official "Flex-Radio" or a recommended 
after-market filter that I could also use?

  Thanks!

  - Jeff, WA6AHL

  - Original Message - 
  From: Larry W8ER 
  To: Flex Reflector 
  Sent: Thursday, January 26, 2006 12:52 PM

  Subject: [Flexradio] Flex SDR-1000 For Sale


  Reluctantly I am selling my SDR-1000. It has the 100 watt amplifier and the built in antenna tuner. It is approximately 1 year old. It also has the 160 meter bandpass filter for anyone that is bothered by local broadcast stations on 160 meters. I will include the Delta 44 sound card and all cables. It is perfect in most every way. It is available immediately for $1450 plus shipping of your choice. 


  email at [EMAIL PROTECTED] or 440-967-0654

  --Larry 


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Re: [Flexradio] Fwd: Re: ARRL FMT: one more win for the SDR-1000

[John Ackermann N8UR]

Jim Lux wrote:

The soundcard program I used, Argo, permits a frequency calibration 
coefficient to be entered.  I used the 1800 Hz third harmonic of the 
WWV/WWVH 600 Hz tone as demodulated by the TS-870S in its AM mode as a 
calibration standard.  When ionospheric fades null the carrier, the 
demodulator distortion peaks and makes the audio third harmonic visible in 
the Argo spectrogram.


Argo is a really excellent tool; one of the guys who does the 
"multi-multi" FMT with me uses it and it has some very cool features for 
this application.  And cool idea about using the distortion to get a 
calibration source!


John

Re: [Flexradio] ARRL FMT: one more win for the SDR-1000

[John Ackermann N8UR]

Jim Lux wrote:

At 05:58 AM 1/19/2006, John Ackermann N8UR wrote:


Jim Lux wrote:

Of course... the SDR1000 does have an advantage because it's a very 
simple receiver with fewer stages to screw things up.



While the SDR-1000 can do a credible job on its own, I just want to 
reinforce that anyone with a signal generator that's locked to a 
decent reference, and a sound card, can measure to small fractions of 
a Hertz using the "delta reference" method I describe at 
http://www.febo.com/time-freq/fmt/technique.html.  You don't need a 
lab full of expensive gear to do it.




Indeed..  The two accuracy limiting things in John's scheme that I see are:
1) Group delay variations across the band in the presence of any drift. 
If the unknown and the reference move across the passband, and there's 
some group delay ripple, the relative phase will change between the 
tones.  If you're integrating for 10 seconds, a phase change of 360 
degrees would be a 0.1 Hz error. THis might be an area where older 
receivers using a long string of tuned LC networks for selectivity would 
be at disadvantage (because each section flips the phase 180 over the 
passband, and they all add up).  You also clearly don't want that exotic 
10 Hz CW crystal filter in the circuit.


Yup.  I normally use a fairly wide bandwidth; in fact, for the last 
test, I used the widest 3100Hz bandwidth in the 3586C selective level 
meter; good thing I did, too, as I mistuned on a broadcast hetrodyne on 
40M, and only after the fact did I find W1AW 1kHz away, but still in the 
bandpass.


2) Uncertainty in the sampling clock of the audio card.  I suppose that 
one can calculate this by measuring the frequency of the "known" 
reference at two frequencies.  A lot of signal generators have a way to 
put an AM modulation on the signal with precisely controlled frequency, 
and that would give you two marks, say, 400 Hz apart, with which to 
calibrate the FFT box.


We've been around the soundcard clock issue several times on the list. 
An advantage of the delta reference method is that you don't care about 
the absolute frequency, only the delta between two closely spaced 
frequencies.  So the clock error is applied to a smaller number (the 
delta between the two tones) and thus has less absolute impact than if 
you were measuring absolute frequency.  My measurements of the Delta 44 
card I use shows that its clock error is in the noise for this test.


Remember that frequency measurement in the HF range doesn't really 
require a super-accurate source -- 1x10e-8 gets you down to 0.1Hz at 
10MHz.  That level of accuracy can easily be met with a $100 surplus 
ovenized oscillator (like an HP 10811A or the older 10544), a GPS 
receiver, and a $100 surplus counter like the HP 5334 (my personal 
low-cost favorite)*.  And that's assuming you're fairly 
fumble-fingered.  With a bit of care, you can set to at least one, and 
maybe two, orders of magnitude better than that (though the aging rate 
will limit how long that accuracy holds).


The GPS receiver needs a 1pps output of some sort. (I tried this with a 
serial output only once, and while the timing of the messages was 
reasonably stable, it wasn't great: about 1ms uncertainty)


Yes, I should have said that.  The good news is that there are lots of 
old Oncore receivers available for a pittance that will do the job.


73,
John

Re: [Flexradio] ARRL FMT: one more win for the SDR-1000

[John Ackermann N8UR]

Jim Lux wrote:

Of course... the SDR1000 does have an advantage because it's a very 
simple receiver with fewer stages to screw things up.


While the SDR-1000 can do a credible job on its own, I just want to 
reinforce that anyone with a signal generator that's locked to a decent 
reference, and a sound card, can measure to small fractions of a Hertz 
using the "delta reference" method I describe at 
http://www.febo.com/time-freq/fmt/technique.html.  You don't need a lab 
full of expensive gear to do it.


Remember that frequency measurement in the HF range doesn't really 
require a super-accurate source -- 1x10e-8 gets you down to 0.1Hz at 
10MHz.  That level of accuracy can easily be met with a $100 surplus 
ovenized oscillator (like an HP 10811A or the older 10544), a GPS 
receiver, and a $100 surplus counter like the HP 5334 (my personal 
low-cost favorite)*.  And that's assuming you're fairly fumble-fingered. 
 With a bit of care, you can set to at least one, and maybe two, orders 
of magnitude better than that (though the aging rate will limit how long 
that accuracy holds).


73,
John

* If you're buying an HP counter, the high-stability option (usually 
001) means that it will have an ovenized oscillator, usually a version 
of the 10811A, so if you're lucky you can kill two birds with one stone. 
 My first 5334B, which cost me $125 on eBay, had that option, and I've 
seen others with similar price tags.

Re: [Flexradio] ARRL FMT: one more win for the SDR-1000

[John Ackermann N8UR]

Eric Ellison wrote:

Folks

Just autta send this whole message thread to ARRL. It really is not that
much fun if the equipment you have evolved at great cost and enjoyment, is
FOO_BAR to the 'standard' being transmitted!

Jim, can't you convince JPL folks to send this test? It more or less is a
goal of part 97. Why shouldn't the masters of this 'art' test the amateurs
of this 'art'. Then we really could celebrate the 'score' rather than the
person who gussed 'off the mark' the luckiest.


In fairness to ARRL, they are aiming the test at a broad audience and 
are trying to reinforce the idea that even with today's modern rigs, 
it's important to have some idea of exactly where you're transmitting. 
The time-nuts are a bit of a fringe element :-).


The group here in Dayton has talked about running our own version of the 
FMT, better suited to the extremophiles.  We just haven't gotten around 
to doing it yet.


John

Re: [Flexradio] ARRL FMT: one more win for the SDR-1000

[John Ackermann N8UR]

Jim Lux said the following on 01/18/2006 07:36 PM:
> At 04:24 PM 1/18/2006, John Ackermann N8UR wrote:
> 
>> Eric Ellison said the following on 01/18/2006 07:01 PM:
>>
>> > Anybody ever wonder if folks out here have even better equipment
>> than ARRL
>> > for generating the test?
>> >
>> >
>> >
>> > Sort of would be fun for folks like yourself, Tom, JPL?, John or
>> others,
>> > with access to millions of dollars in equipment to do the "Test".
>>
>> Several of us on the "time-nuts" list participated.  The equipment ARRL
>> uses is nothing all that special -- a Z3801A GPS-disciplined oscillator
>> clocking a surplus HP frequency counter.  The interesting thing is that
>> (at least last year) the audio tone generator they used was an old
>> Heathkit!  That makes frequency stability during the test a real issue,
>> and means that you need to be careful to measure each band during the
>> time that ARRL is.  I should go back to my data and see what the tone
>> was on a single band at the beginning versus the end of the test.
>>
>> I am pretty confident that I can measure a CW tone off the air down to a
>> few milliHertz accuracy given a minute of more of carrier to work with
>> (and enough lead time to get the measurement gear in the ballpark).
> 
> 
> 
> As I recall, you can measure the phase of a tone with an uncertainty of
> 1/sqrt(T * CNR), where T is the integration time, and CNR is the carrier
> to noise spectral density ratio (C/Nzero).  If you've got a SNR of say,
> 10 dB in a 2kHz bandwidth, that's a CNR of 2, or a phase uncertainty
> for a 50 second measurement of 1/1000 radian (0.057 degree?)
> 
> I can't recall off the top of my head how to convert a phase uncertainty
> into a frequency uncertainty (frequency just being the derivative of
> phase), but it should be straight forward.

I haven't worked through that bit of math, I'm just going on the results
we've gotten.  The method I use is to inject a known signal very close
(within, say, 100Hz) of the unknown signal, and measure the delta
between the two using a sound card.  By using a high decimation rate and
reasonably deep FFT, you can get resolution down well below a
milliHertz.  The problem is getting enough samples to fill the FFT; you
end up dealing with an effective sample rate after decimation of maybe a
few hundred samples/second, which means that you need a long time to get
a useful output from the FFT.

The software I use, Baudline (http://www.baudline.com) is a Linux based
spectrum analyzer package that has some neat features, including the
ability to automatically measure the delta between two signal peaks.  It
 makes the whole process pretty easy.

> It would be interesting to figure out a more meaningful competition,
> where ionospheric effects are compensatable, if you're clever.  Perhaps
> measuring the relative phases/frequencies/amplitudes of multiple tones
> that are reasonably close together?
> 
> Something that could be normalized to your propagation path.  Otherwise,
> the guy sitting in the parking lot at W1AW has a huge advantage.  Maybe,
> your results are scaled by the SNR or something?

We've thought a little about what kind of format would be really
challenging for the test, and measuring the delta between two tones is
one interesting idea.  None of the folks I've talked to very much like
the format of the last two years, where you have to reduce to an audio
tone that's meaningless because the transmission in in SSB mode.

73,
John

Re: [Flexradio] ARRL FMT: one more win for the SDR-1000

[John Ackermann N8UR]

Eric Ellison said the following on 01/18/2006 07:01 PM:

> Anybody ever wonder if folks out here have even better equipment than ARRL
> for generating the test? 
> 
>  
> 
> Sort of would be fun for folks like yourself, Tom, JPL?, John or others,
> with access to millions of dollars in equipment to do the "Test".

Several of us on the "time-nuts" list participated.  The equipment ARRL
uses is nothing all that special -- a Z3801A GPS-disciplined oscillator
clocking a surplus HP frequency counter.  The interesting thing is that
(at least last year) the audio tone generator they used was an old
Heathkit!  That makes frequency stability during the test a real issue,
and means that you need to be careful to measure each band during the
time that ARRL is.  I should go back to my data and see what the tone
was on a single band at the beginning versus the end of the test.

I am pretty confident that I can measure a CW tone off the air down to a
few milliHertz accuracy given a minute of more of carrier to work with
(and enough lead time to get the measurement gear in the ballpark).  Of
course, propagation can cause wiggles much greater than that, so you
need to take my X.XXXHz readings with that in mind (and ARRL only
reports their measured frequency to two decimal places).

73,
John

Re: [Flexradio] ARRL FMT: one more win for the SDR-1000

[John Ackermann N8UR]

Eric Ellison said the following on 01/18/2006 06:40 PM:

> Spent some enjoyable time on John Ackerman's website today, looking at his
> time stuff and measurement set up. I wonder if he used the SDR-1000 with his
> laboratory?

We used the SDR-1000 as a monitor receiver since the technique we were
using for the main measurement didn't allow easy listening to the voice
announcements.  (I use "we" because we ran multi-multi, with five of us
using different gear to measure the frequency.)

Interestingly, several of us who've compared notes found that we were
all further from W1AW than in past years, and closer to each other!
There may have been significant propagation effects going on, or
(particularly since we all seemed to be low on all frequencies vs. W1AW)
something in the W1AW measurements themselves.

73,
John

Re: [Flexradio] DIP OCXO for SDR

[John Ackermann N8UR]

I'm traveling for a few days and don't have all my stuff handy, but
Gerald pointed me to a device from (I think) Silicon Industries in Texas
that looks very promising.  They have VCXOs up to 400MHz that have some
sort of on-board divider/synthesizer/nco so they can deliver any
frequency in range with short lead time.  The phase noise doesn't look
too bad, either.  It's the part I'm focusing on right now for the
Reflock unit.  I want to say the part number is something like Si520,
but that may be wrong.

John


Eric Ellison said the following on 01/07/2006 11:08 PM:
> Tim
> 
> Thanks. I swear that Gerald said the current VF part was sine wave output. I
> saw the posts about the Greenray a while back and just don't know. This is
> the first time in my searches that I found a 200 mhz VC part which is
> available without horrific lead times and no quantity one. If the Crystek
> part will work in our external closed loop design to drive the SDR
> accurately then I'm for giving it a shot. That price is not bad either. At
> times I had seen $80 + parts and they were not low phase noise, or voltage
> controlled, just +/- 25 ppm TC parts. Although this is a 50 ppm part I think
> that I saw it could be pulled +/- 500 ppm.
> 
> Thanks for the response.
> 
> Comments?
> 
> Eric2
> 
> 
> -Original Message-
> From: Tim Ellison [mailto:[EMAIL PROTECTED] 
> Sent: Saturday, January 07, 2006 10:32 PM
> To: Eric Ellison; John Ackermann N8UR
> Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz
> Subject: RE: [Flexradio] DIP OCXO for SDR
> 
> Eric,
> 
> The VF VCXO listed below has a max frequency at 200 MHz.  The XO
> currently in use, the VF 161 has a max frequency of 300 MHz.  Using a
> device at either end of its rated frequency may suffer from precision
> and/or accuracy errors.
> 
> The Crystek   is much closer, but the output is a sine wave rather than
> PECL(positive emitter coupled logic) which is the output of the current
> XO.  I am not sure if this will make a difference or not with the
> devices being designed.
> 
> I did find this VCXO that is very close to the VP161 from Greenray, but
> I received some less than satisfactory comments about the company
> 
> http://greenrayindustries.com/library/ZT620.pdf
> 
> -Tim
> ---
> Tim Ellison ( [EMAIL PROTECTED] )
> Integrated Technical Services ( http://www.itsco.com )
> 
> 
> -----Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison
> Sent: Saturday, January 07, 2006 9:01 PM
> To: 'Eric Ellison'; 'John Ackermann N8UR'
> Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz
> Subject: Re: [Flexradio] DIP OCXO for SDR
> 
> John (and others on this thread)
> 
> Magnus - SM4RWI mailed me off list of a Valpey Fisher 200 VCXO offering
> with
> low phase noise. The VF 960/961. I could not find any ready sources for
> this
> part and did not request sample or quote. However, it is a pretty nice
> piece.
> 
> 
> http://www.mfelectronics.com/products/vcxo/
> 
> 
> I decided to go back out and do my occasional search for an available
> part
> with low phase noise and 200 mhz VC.
> 
> Newark is supplying a Crystek 200 mhz VCXO in stock for about $45 Dip
> and
> $58 smt.
> 
> See PDF.
> 
> http://www.crystek.com/spec-sheets/CCO-083_085.pdf
> http://www.mouser.com/catalog/624/656.pdf
> 
> If we are talking about temp stabilizing and disciplining external to
> the
> radio, these might be good considerations for the conventional (not
> computer
> or FPGA aided) GPS - 10 mhz phase locking system.
> 
> Someone could take a look and see if the specs are acceptable.
> 
> Eric2
> 
> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison
> Sent: Friday, January 06, 2006 4:17 PM
> To: 'John Ackermann N8UR'
> Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz
> Subject: Re: [Flexradio] DIP OCXO for SDR
> 
> John
> 
> Yes! Gerald HAS really moved a lot of lives with something that actually
> works, is available, and works very well! It sure has spawned a LOT of
> interesting projects and experimentation.
> 
> I agree totally that we should 'brainstorm' a solution for getting the
> 200
> mhz off or on, or around, and or back into the SDR-1000. Something
> fairly
> flexible and not too difficult to accomplish.
> 
> I don't think that any of this is in conflict with others, and nothing
> is
> really 'fractionating' the mass of folks in spite of 'parallel' projects
> going on. If anything we are getting some crosspollination. At this
> point
> 

Re: [Flexradio] DIP OCXO for SDR

[John Ackermann N8UR]

Eric Ellison wrote:

[ everything trimmed ]

It sounds like there are several groups doing a lot of interesting 
things with FGPAs that extend way beyond just frequency stability.  I 
think that's really great, and thank Gerald for creating such a great 
base for creative people to play.


From my (and TAPR's) perspective, we want to do a Reflock-based design 
because it will have a broader use than just the SDR-1000.  For example, 
 with a 64MHz VCXO, it can work with the Ettus Research USRP software 
radio.  I can also see it serving as an external clock for a sound card 
to eliminate that source of frequency uncertainty.  So, I don't see any 
conflict at all between what we're doing and the other approaches.


The one SDR1k specific item I'd like to see, whether TAPR produces it or 
Gerald does, is a "civilized" board that will plug into the reference 
oscillator socket to allow a better interface to an external signal. 
I've started looking into that and we'll work with Gerald to figure out 
how best to offer that.  It's mainly a matter of finding a buffer/level 
converter chip that will take a single-ended input and convert it to a 
differential signal at the right level for the DDS chip (suggestions 
welcome; I've started researching the chipmaker sites, but haven't found 
an obvious answer yet).


73,
John

Re: [Flexradio] DIP OCXO for SDR

[John Ackermann N8UR]

Sorry I couldn't join in the fun; just too many things going on.

TVB's PIC divider is a really elegant hack, and works very well.  I'm
currently working on a project for TAPR for a universal divider (to take
any common frequency standard output and drop it to 1pps) and started
out planning to use the PIC design, but changed to a CPLD because that
offered more flexibility (or at least a more comprehensible programming
model) for what I was trying to do, which has more options than Tom
considered.

I suspect that if you're doing something with an FPGA or CPLD anyway,
you'll have the gates available in that chip to do the division without
having to add another device, so I'd consider that first before adding
another block to the system.

John


Eric Ellison said the following on 01/05/2006 07:14 PM:
> Folks
> 
> Missed you on our Teamspeak session last night "It's about time"!
> 
> Had a good discussion amongst a few people working on both the projects
> (Xylo) and Flex. Guess the fantastic Texas - USC entertainment got most
> others!
> 
> Bob K5KDN is working on a Timebase board, chassis etc and has a Jupiter and
> nice 10 mhz Ovenized VCXO interfaced and building a board which will squat
> down on the DIP connector on the Jupiter. 
> 
> On the Xylo side Bill - KD5TFD published a picture of his breadboard of the
> Jupiter interfacing to the Xylo board, which will eventually pass
> frequency/phase information back to the PowerSDR software.
> 
> I am looking for more information on anyone who has produced a complete
> circuit design published here several months ago by Tom Clark. Based on an
> original design by Tom van Baak and enhanced by Tom Clark.
> 
> This is really an inspired design! 
> 
> PIC header is published here without permission, however, I did not note a
> copyright, and Tom made it available on the Forum several months ago.
> 
> If it uses 10 MHZ this is the way to go!
> 
> ; --
> ;
> ; Title:
> ;
> ;   10 MHz frequency divider
> ;
> ; Function:
> ;
> ;   This PIC 16c84 program is designed to divide a 10 MHz frequency
> ;   source down to 1 Hz (1 PPS).
> ;
> ;   Since several extra output pins are available the program creates
> ;   a total of 9 square wave outputs -- one for each frequency decade
> ;   from 100 kHz to 0.001 Hz (1000 s).
> ;
> ;   A STOP input and a 1 PPS synchronization input are also provided.
> ;   Raising the STOP input high stops and resets the divider. The
> ;   divider resumes on the leading edge of the 1 PPS SYNC input. The
> ;   1 PPS output will be synchronized to the 1 PPS SYNC input to less
> ;   than 1.2 us (three PIC instructions at 10 MHz).
> ;
> ;   The following chip schematic shows the assignment of each pin.
> ;
> ;--   --
> ;   100 kHz <-   RA2 |1---   18| RA1 -> Red LED
> ; Green LED <-   RA3 |2  17| RA0 <= Stop input
> ; 1PPS SYNC => T0CKI/RA4 |3  16| OSC1/CLKIN  <= 10 MHz input
> ;+5 VDC -> /MCLR |4  15| OSC2/CLKOUT -- N/C
> ;   GND ->   Vss |5   16C84  14| Vdd <- +5 VDC
> ;10 kHz <-   INT/RB0 |6  13| RB7 -> 1000 s
> ; 1 kHz <-   RB1 |7  12| RB6 -> 100 s
> ;   100  Hz <-   RB2 |8  11| RB5 -> 10 s
> ;10  Hz <-   RB3 |9  10| RB4 -> 1 Hz / 1 PPS
> ;---
> ;
> ; Implementation:
> ;
> ;   To generate a 10 kHz square wave at 50% duty cycle an output pin
> ;   must be flipped every 50 us (125 instructions at 10 MHz clock).
> ;   This program does not use TMR0, the pre-scaler, or interrupts.
> ;   Instead it relies on the fact that given an accurate 10 MHz clock
> ;   each PIC instruction takes precisely 400 ns and the main loop has
> ;   been designed to use exactly 125 instructions.
> ;
> ;   The 100 kHz frequency (10 us period) is generated by setting an
> ;   output pin on and off every 25 cycles. Since 25 is an odd number
> ;   it is not possible for the PIC to generate this square wave with
> ;   a 50% duty cycle. Instead a 20% duty cycle (5 cylcles on and 20
> ;   cycles off) was chosen for this frequency output. A total of 5
> ;   pairs of 100 kHz bit set/clear code are carefully interspersed
> ;   within the 50 us main loop.
> ;
> ;   Pins RA0 and RA4 are not used to drive a LED. RA4 is a Schmidt
> ;   trigger input and O.C. output. It is used as the SYNC input.
> ;   The data sheet says not to toggle RA0 under some conditions so
> ;   it is used as the STOP input.
> ;
> ; Version:
> ;
> ;   1998-Au

Re: [Flexradio] DIP OCXO for SDR

[John Ackermann N8UR]

Great plan, John.  I only had access to the 5052A for a day, so was 
pretty limited in what I could do; it's great that you'll be able to 
carry things forward.


The one addition I would suggest is that you duplicate the DDS output 
measurements using the 10MHz source as well as the VF oscillator.  That 
would add to my sketchy info about the effect of the multiplier on phase 
noise.


I was not happy with the results I got, I think due to the way I was 
coupling out of the DDS, which was essentially a x1 scope probe with 
less-than-perfect grounding.  After the fact, I redid the connection 
with a 50 ohm  series resistor at U1 pin 6 (actually, mounted into a via 
on that line) and a short piece of RG-174 feeding a buffer amplifier.  I 
think something like that will give better results.


By the way -- I looked at the AD9854 data sheet and it includes several 
phase noise plots.  From those, you would gather that there is a cost in 
using the internal multiplier, but that it doesn't scale with DDS output 
frequency.  Also, from a quick read you could get the impression that 
the phase noise of the reference clock doesn't really matter (within 
reason, of course); they show the output phase noise plot without any 
reference to the noise of the clock.


73,
John


[EMAIL PROTECTED] wrote:
This is cool.  It's great to be able to discuss the nuances of what 
really goes on within our radios.  Spreading the word is a very good

thing.  I checked out John's(N8UR) web site and I'm inspired.  I have
an E5052A Signal Source Analyzer setting here and plan to make a few
measurements.

Here's the plan so far:

	i. 	measure phase noise of a 10MHz crystal 
			(it will probably be limited by the E5052A)

ii. the 200MHz VF1611
iii.  DDS output with VF1611 as the clock at:
1MHz
5MHz
10MHz
50MHz

Anyone have any additional ideas?  I'm all ears.

73,
k2ox


-Original Message-
From: richard allen [mailto:[EMAIL PROTECTED] 
Sent: Wednesday, January 04, 2006 5:39 PM

To: John Ackermann N8UR
Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz
Subject: Re: [Flexradio] DIP OCXO for SDR

Gentlemen,

The DDS does Direct Digital Synthesis hence the name.  It does not 
divide
back to anything but runs an phase accumulation engine at 200 MHz (or 
whatever
the clock rate) that produces output values to the dac at that rate.  


No division is performed.

Richard W5SXD

John Ackermann N8UR <[EMAIL PROTECTED]> wrote:
(01/04/2006 16:09)



[EMAIL PROTECTED] wrote:


First of all, any osc multiplied up widens its sidebands
(phase noise) by the multiplication factor and the inverse is
also true. The DDS does a 20X to 200MHz and a divide by 20 to 
get back to 10MHz.  I guess it's academic at this point how 
much jitter is added by the DDS until someone measures it.


You're only dividing back to 10MHz if that's the operating frequency. 
At higher operating frequencies, the division doesn't equal the 
multiplication (and of course, at lower ones it exceeds it).  Measuring 
the DDS output lets us see the phase noise where it counts, taking into 
account both multiplication and division, rather than just at the 
fundamental frequency of the reference.



Second, Rubidium standards are not intended to be used as local 
oscillators. They have terrible phase noise.  They are intended 
to be used in timekeeping.  It is their long term drift that 
excels, not short term phase noise. 


Agreed in general -- though there's a wide difference in performance 
between different types of Rb; some use FM modulation of the xtal, which 
results in horrible phase noise, while others, like the 5065A, don't. 
My post wasn't suggesting that you use an Rb as the primary reference. 
However, the DDS output when driven by 10MHz shows the effect of the 
multiplication, which is all I was trying to do.  My web page also has a 
plot of the HP 5065A phase noise at 10MHz, so you can see the difference 
in noise between the raw and multiplied frequencies.


John


http://www.febo.com/geekworks/sdr1k/sdr1k_phase/index.html has 
screenshots that show the phase noise at the output of the DDS for the 
standard 200MHz oscillator, and an HP Rubidium frequency standard at 
10MHz multiplied by 20 in the DDS.  You can clearly see the phase-noise 
hit caused by the multiplication.


John

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Re: [Flexradio] DIP OCXO for SDR

[John Ackermann N8UR]

Richard, that's a question I've been meaning to ask someone -- whether
there's any phase noise improvement resulting from the (apparent)
division of the clock signal by the DDS, or whether the output phase
noise is always the same as, or worse than (due to imperfection in the
DDS process), the reference.

John


richard allen said the following on 01/04/2006 05:39 PM:
> Gentlemen,
> 
> The DDS does Direct Digital Synthesis hence the name.  It does not 
> divide
> back to anything but runs an phase accumulation engine at 200 MHz (or 
> whatever
> the clock rate) that produces output values to the dac at that rate.  
> 
> No division is performed.
> 
> Richard W5SXD
> 
> John Ackermann N8UR <[EMAIL PROTECTED]> wrote:
> (01/04/2006 16:09)
> 
> 
>>[EMAIL PROTECTED] wrote:
>>
>>>First of all, any osc multiplied up widens its sidebands
>>>(phase noise) by the multiplication factor and the inverse is
>>>also true. The DDS does a 20X to 200MHz and a divide by 20 to 
>>>get back to 10MHz.  I guess it's academic at this point how 
>>>much jitter is added by the DDS until someone measures it.
>>
>>You're only dividing back to 10MHz if that's the operating frequency. 
>>At higher operating frequencies, the division doesn't equal the 
>>multiplication (and of course, at lower ones it exceeds it).  Measuring 
>>the DDS output lets us see the phase noise where it counts, taking into 
>>account both multiplication and division, rather than just at the 
>>fundamental frequency of the reference.
>>
>>
>>>Second, Rubidium standards are not intended to be used as local 
>>>oscillators. They have terrible phase noise.  They are intended 
>>>to be used in timekeeping.  It is their long term drift that 
>>>excels, not short term phase noise. 
>>
>>Agreed in general -- though there's a wide difference in performance 
>>between different types of Rb; some use FM modulation of the xtal, which 
>>results in horrible phase noise, while others, like the 5065A, don't. 
>>My post wasn't suggesting that you use an Rb as the primary reference. 
>>However, the DDS output when driven by 10MHz shows the effect of the 
>>multiplication, which is all I was trying to do.  My web page also has a 
>>plot of the HP 5065A phase noise at 10MHz, so you can see the difference 
>>in noise between the raw and multiplied frequencies.
>>
>>John
>>
>>
>>>http://www.febo.com/geekworks/sdr1k/sdr1k_phase/index.html has 
>>>screenshots that show the phase noise at the output of the DDS for the 
>>>standard 200MHz oscillator, and an HP Rubidium frequency standard at 
>>>10MHz multiplied by 20 in the DDS.  You can clearly see the phase-noise 
>>>hit caused by the multiplication.
>>>
>>>John
>>>
>>>___
>>>FlexRadio mailing list
>>>FlexRadio@flex-radio.biz
>>>http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
>>>
>>>
>>
>>
>>___
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>>http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
> 
> 
> 
> 

Re: [Flexradio] DIP OCXO for SDR

[John Ackermann N8UR]

[EMAIL PROTECTED] wrote:

First of all, any osc multiplied up widens its sidebands
(phase noise) by the multiplication factor and the inverse is
also true. The DDS does a 20X to 200MHz and a divide by 20 to 
get back to 10MHz.  I guess it's academic at this point how 
much jitter is added by the DDS until someone measures it.


You're only dividing back to 10MHz if that's the operating frequency. 
At higher operating frequencies, the division doesn't equal the 
multiplication (and of course, at lower ones it exceeds it).  Measuring 
the DDS output lets us see the phase noise where it counts, taking into 
account both multiplication and division, rather than just at the 
fundamental frequency of the reference.


Second, Rubidium standards are not intended to be used as local 
oscillators. They have terrible phase noise.  They are intended 
to be used in timekeeping.  It is their long term drift that 
excels, not short term phase noise. 


Agreed in general -- though there's a wide difference in performance 
between different types of Rb; some use FM modulation of the xtal, which 
results in horrible phase noise, while others, like the 5065A, don't. 
My post wasn't suggesting that you use an Rb as the primary reference. 
However, the DDS output when driven by 10MHz shows the effect of the 
multiplication, which is all I was trying to do.  My web page also has a 
plot of the HP 5065A phase noise at 10MHz, so you can see the difference 
in noise between the raw and multiplied frequencies.


John

http://www.febo.com/geekworks/sdr1k/sdr1k_phase/index.html has 
screenshots that show the phase noise at the output of the DDS for the 
standard 200MHz oscillator, and an HP Rubidium frequency standard at 
10MHz multiplied by 20 in the DDS.  You can clearly see the phase-noise 
hit caused by the multiplication.


John

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Re: [Flexradio] DIP OCXO for SDR

[John Ackermann N8UR]

Jim Lux wrote:

At 10:11 AM 1/4/2006, [EMAIL PROTECTED] wrote:


The SDR1000 can use clocks between 10MHz and 200MHz so long as when
multiplied by an integer it equals 200 MHz.  I use a 10MHz TCXO.

73,
k2ox



However, when you multiply up using the internal VCO, the phase noise takes 
a hit. You might wind up with poorer noise (but more accurate frequency) 
multiplying up from a 10 MHz TCXO.


http://www.febo.com/geekworks/sdr1k/sdr1k_phase/index.html has 
screenshots that show the phase noise at the output of the DDS for the 
standard 200MHz oscillator, and an HP Rubidium frequency standard at 
10MHz multiplied by 20 in the DDS.  You can clearly see the phase-noise 
hit caused by the multiplication.


John

Re: [Flexradio] Software taming the wandering oscillator - a thought

[John Ackermann N8UR]

Eric Ellison said the following on 01/02/2006 06:25 PM:

> This is the way to go for three projects. Pardon my ignorance, but is the
> V-F Osc a pluggable part? This is the best of all worlds. Unmodified, the

Yes, it's a can oscillator with 4 pins.  It basically has the same
footprint as a 14 pin (I think) DIP package, but with only four pins,
one at each corner.

John

Re: [Flexradio] Software taming the wandering oscillator - a thought

[John Ackermann N8UR]

For the tests that I did, I pulled the operating frequency from pin 6 of
U1 through a 50 ohm resistor and a short piece of RG-174 cable.  That
gave a nice high-level signal, and since I wasn't actually using the
radio for anything at the time, I didn't really care about the impact
the tap might have on performance.

If you want to get the 200MHz signal, I think you will need to have a
pretty high impedance tap with a buffer amplifier right there in order
to get a useful signal out without degrading the clocking of the DDS.

I've suggested to Gerald that the "right" answer to the mechanical
issues around the oscillator could be to build a small board with a
single ended to differential buffer/converter and an SMA connector that
would plug in where the oscillator now goes.  That would provide a clean
interface for whatever oscillator you might want to use.  The other half
of the equation would be to make an external board to hold the current
oscillator with an SMA connection for the output.  That setup would make
it very easy to add thermal control, and also to tap the signal for
other purposes.

The oscillator interface board could well be part of the final version
of the TAPR Reflock solution for the SDR-1000, but no promises yet as
we're still noodling the design.

73,
John


Eric Ellison said the following on 01/01/2006 11:36 PM:
> Bill
> 
> I am reposting this, since I never saw any comments or answer. There must be
> some 'time nut' familiar enough with the SDR to postulate an answer to the
> question of WHERE and HOW do we get a signal to reference back in external
> hardware/software. And what the implications are for getting to our accuracy
> objective. Since this is a high level sig probably with adequate fan out it
> would really be better than trying to buffer the LO so we can count it.
> 
> Eric2
>  
> 
> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Bill Tracey
> Sent: Monday, December 26, 2005 9:47 AM
> To: FlexRadio@flex-radio.biz
> Subject: [Flexradio] Software taming the wandering oscillator - a thought
> 
> Current thoughts on disciplining the wandering 200 MHz osc are to tap off 
> the output of the 200 MHz clock. buffer it and then feed it to an FPGA or 
> microcontroller to be counted against a GPS locked 1pps or 10 khz reference 
> and then to supply the count data back to the PowerSDR software where it 
> will do the right thing to do frequency correction in software.
> 
> What if we were to instead take the output of the DDS and count that 
> instead?  Specifically thinking of tapping the output of U1 (DS9OLV028) on 
> the TRX board  which is a robust 3v square wave clocking the bus 
> switches.   Seems it would be easier to count this than the output of the 
> 200 MHz oscillator.  Any thoughts on what this would do to the fidelity of 
> corrections we can do in software?  Any other gotchas?  There appear to be 
> a number of via's on the TRX board this signal could be tapped from.   This 
> would probably have to be tapped with a shielded tap (RG174 coax?)  to 
> prevent it from radiating excessively, but seems to doable (at least to 
> this novice).
> 
> Regards,
> 
> Bill (kd5fd)
> 
> 
> 
> 
> ___
> FlexRadio mailing list
> FlexRadio@flex-radio.biz
> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
> 
> 
> ___
> FlexRadio mailing list
> FlexRadio@flex-radio.biz
> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
> 
> 

[Flexradio] Measuring the SDR-1000's latency

[John Ackermann N8UR]

While I was setting up to record audio from several radio time sources
for the leap second last night (my leap second web page is at
http://www.febo.com/time-freq/leapsecond-2005), I realized that it would
be easy to use the same configuration to measure the delay of the audio
output of the two receivers (SDR-1000 and Yaesu FT-817) when both were
tuned to the same signal on the same antenna.  I ran that experiment
today, using WWV on 15MHz.  The short answer is that with my setup, the
delay is 187.6 milliseconds.

More detailed results, with screenshots, are at
http://www.febo.com/geekworks/sdr1k/sdr1k_latency.

I was using 1.4.5 preview 4 and the DSP buffer size was set to 2048; the
sound card buffer size was 1024.  I think these were the defaults when I
installed the software, but if they're not appropriate, someone let me
know and I can rerun the experiment with different values.

More details about the test setup are at the web page.

Happy New Year!

73,
John

Re: [Flexradio] A question on Frequency stability vs. Temperature

[John Ackermann N8UR]

Insulation will slow down the response to external temperature
variations, but unless there's a heat source inside the insulated area,
it won't prevent the change (sooner or later, the internal temperature
will match the external).

One very simple answer, that I think Gerald has been playing with, is to
use a heating element to raise the temperature of the oscillator above
the ambient.

In a packet radio project many years ago, I was working with Kantronics
UHF data radios that had horrible temperature stability that was
exacerbated by the fact they were used in non-temperature controlled
environments.

We tried a couple of ways to fake a crystal oven.  The easiest, and most
successful, was a crystal heater that you could buy from the Yaesu parts
department.  It was a power thermistor mounted to a clip that would
slide over the crystal can.  Attached to 12 volts, it would heat the
crystal up to something over 100 degrees F (we never measured the exact
temperature).  Those solved our temperature stability problems, but I
suspect that it "cooked" some of the crystals (which were spec'd for
room temperature operation) because after a couple of years we found
some rocks that would no longer net to frequency.

Something similar might work with the V-F oscillator can.

John


[EMAIL PROTECTED] said the following on 12/31/2005 07:31 AM:
> Folks
> 
> Yes, Bob N4HY mentioned on Teamspeak that he had 'insulated' the osc with 
> some material which cut down on drift. Perhaps he could elaborate a bit more 
> on the scheme he used.
> 
> Eric2
> 
> -- Original message -- 
> From: KD5NWA <[EMAIL PROTECTED]> 
> 
> 
>>I've heard it on Teamspeak that when a scheme like that has been 
>>tried it worked very well. 
>>
>>Thermal stability like you mentioned, along with electronic 
>>compensation of the clock by comparing it to a GPS clock is one of 
>>the projects the Xylo will be used for. 
>>
>>At 12:49 AM 12/31/2005, Tim Ellison wrote: 
>>
>>>I have a question about frequency stability of the SDR1K in regard to 
>>>variable temperatures inside the SDR1K. The reason for concern is 
>>>frequency drift while working digital modes. For the sake of this 
>>>argument and staying on point, let's assume that the frequency delta is 
>>>significant, although in reality it probably is insignificant. 
>>>
>>>
>>>Some initial background information. I am seriously thinking about 
>>>installing a temperature-proportional cooling fan speed controller in 
>>>the SDR1K to further reduce fan noise. The controller is not designed 
>>>to provide a stable temperature (thermostatically controlled), it just 
>>>increases the fan's RPMs as the temperature increases until it reaches 
>>>max RPMs @ 105 F. I assume that since the fan is not providing constant 
>>>CFM air flow, under high duty cycle operation, there will be a more 
>>>rapid rise in temperature until the fan is running at full speed, at 
>>>which some level of temperature equilibrium is reached, as opposed to 
>>>having the fan run at full speed all the time resulting in a temperature 
>>>change that would be less drastic. The net effect is that the internal 
>>>temperature will vary more with the fan controller therefore resulting 
>>>in more drift in the XO. 
>>>
>>>I am aware of the ability to use external precision clock sources to 
>>>more precisely drive the DDS, but in my current configuration, the 
>>>Valpey-Fisher VF-161 XO is utilized and is sensitive to frequency drift 
>>>with changes in temperature. From the specs, the max temperature for 
>>>the XO is 85 C and the stability is +/- 20 ppm. 
>>>http://www.valpeyfisher.com/PDFs/vf161_E.pdf 
>>>
>>>Assuming temperature stabilization is warranted, my question is this - 
>>>what advantages / disadvantages would there be for trying to minimize 
>>>temperature variations of the OX by adding some insulating material 
>>>(Styrofoam maybe) around the XO or by adding an external precision 
>>>crystal heater ( @ 40 C) to *stabilize* the temperature at a fixed value 
>>>and hence the frequency drift? 
>>>
>>>An example of the precision crystal heater is found here: 
>>>http://www.kuhne-electronic.de/english/special/crystalheater.htm 
>>>
>>>Any and all comments welcome. Thanks! 
>>>
>>>-Tim 
>>>--- 
>>>Tim Ellison 
>>>Integrated Technical Services 
>>>Apex, NC USA 
>>>919.674.0044 Ext. 25 / 919.674.0045 (FAX) 
>>>919.215.6375 - cell 
>>>
>>PGP public key available at all public KeyServers <<< 
>>>
>>>
>>>
>>>
>>>___ 
>>>FlexRadio mailing list 
>>>FlexRadio@flex-radio.biz 
>>>http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz 
>>
>>
>>Cecil Bayona 
>>KD5NWA 
>>www.qrpradio.com 
>>
>>"I fail to see why doing the same thing over and over and getting the 
>>same results every time is insanity: I've almost proved it isn't; 
>>only a few more tests now and I'm sure results will differ this time ... " 
>>
>>
>>___

Re: [Flexradio] External clock problems

[John Ackermann N8UR]

did you change jumpers SV1 and SV2 (which switch between differential
and single-ended clock input for the DDS chip)?  I'm not sure what
difference that might make; when I did my phase noise tests, the jumpers
didn't seem to make much difference.

One other possibility might be a ground loop problem.

73,
John


Bob Tracy said the following on 12/30/2005 05:42 PM:
> Hi,
> 
> Has anyone had any experience using an external clock with the SDR-1000 they
> would like to share?  I built a 10 mHz GPSDO that seems to be working just
> fine.  It puts out a nice 1.7 V P-P sine wave into a 50 ohm load which is
> within the +4 to +14 dBm range required by the SDR-1000.  I installed the
> FlexRadio External Clock kit which is just a 14 pin header, some coax, a
> bnc, and a 50 ohm resistor.
> 
> When I try to use the external clock, I get really distorted audio coming
> out of the radio.  I have switched back to the internal oscillator a couple
> of times just to make sure the problem really was in the external circuit.
> The radio works normally using the internal oscillator.  I don't see any
> garbage on the external oscillator signal using a 100 mHz scope.
> 
> One other mystery is the amplitude calibration of the SDR-1000 itself.  I am
> calibrated at -73 dBm using an XG-1 calibrator.  When I connect the external
> oscillator to the SDR-1000 antenna input (using the internal clock) I only
> get a reading of -2.3 dBm.  This is with the preamp off.  According to my
> calculations, it should be reading somewhere around +8 dBm.
> 
> Anyone have any suggestions on the problem?
> 
> Bob, K5KDN
> 
> 
> 
> 
> 
> ___
> FlexRadio mailing list
> FlexRadio@flex-radio.biz
> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
> 
> 

[Flexradio] SDR-1000 Frequency Stability and Phase Noise Tests

[John Ackermann N8UR]

I used the holidays to do a set of tests of the SDR-1000's frequency
stability and phase noise (I got temporary access to an Agilent phase
noise measurement system to make those possible.

I was able to measure the frequency offset, warmup drift, and
frequency-vs.-temperature performance of the SDR-1000 with its stock
oscillator.

I also did a similar set of tests of a prototype Reflock-II frequency
stabilizer locking a 100MHz low-jitter oscillator to a 10MHz TCXO.

I'm not particularly happy with the phase noise results; due to time
constraints we didn't have a chance to properly design the interface and
I think there are some external factors that make the numbers look worse
than they are.  I hope I'll get a chance to play with the phase noise
box again and get some better results.  But there's still a useful
comparison of the noise of the standard 200MHz oscillator versus an
external 10MHz reference multiplied by 20; you can really see how the
phase noise is increased by multiplication.

Anyway, the results are at http://www.febo.com/geekworks/sdr1k.

73,
John

Re: [Flexradio] Frequency stability and calibration

[John Ackermann N8UR]

[EMAIL PROTECTED] said the following on 11/22/2005 08:29 PM:

> Also a comment about the Rubidium, Cesium and Crystal oscillators.
> Oscillators are characterized by short term(phase noise) and long 
> term(drift) freq stability. The phase noise it what concerns us 
> most when it comes to receiving.  We want it low enough so that it 
> doesn't swamp weak signals. Ideally it should be >10db below the
> noise floor of the receiver so as to not reduce sensitivity and
> hence dynamic range.  It is the 'Q' of the resonant component(s) 
> that determine the phase noise.  The quartz crystal is still the
> leader when it comes phase noise.  Rubidium and Cesium are superior
> in time keeping (long term stability), but have awful phase noise. 
> These are the 'real' atomic clocks. The navy is the largest user 
> of these.  No GPS under water! Regarding GPS, its timing is 
> based on the Cesium clocks.

Being slightly insane, I gathered up the published stability and phase
noise specs for a bunch of oscillators and synthesizers and put them in
a single table at http://www.febo.com/time-freq/hardware/specs.html.
The HP 5065A Rb, for example, has phase noise of -93dBc at 1Hz, and -140
at 1kHz.  The 5061A Cs with normal tube is only -82dBc at 1Hz but is
also -140 at 1kHz.  The 10811A crystal ranges (depending on model) from
-95 to -103dBc at 1Hz, and -145 to -162 at 1kHz.

The small Rbs like the Efratom "bricks" that are available on eBay, on
the other hand, are pretty horrible as they use FM modulation as part of
the loop detection.

Of course, the problem is that in the SDR-1000 we are multiplying the
10MHz external reference to 200 MHz, and that multiplication is going to
multiply the phase noise as well.  The question is whether a "low
jitter" can oscillator at 200 MHz is better than a really good crystal
(or even Rb) at 10MHz, multiplied by 20.  I hope to do some measurements
over Christmas to answer that question.

73,
John

Re: [Flexradio] Frequency calibration etc

[John Ackermann N8UR]

Well, you motivated me to do a simple test.  I'm using the Baudline
signal analysis program under Linux and clocking the sound card at
(nominal) 96ksamples/second.

I am currently injecting a 100mv p-p signal at 11.025kHz (to simulate
the SDR-1000 IF output) into one channel of my Delta 44 card.  The
signal is coming from an HP 3325A synthesizer locked to an HP 5065A
Rubidium standard.

I'm using Baudline to decimate and downconvert the signal to get a few
Hz spread across the screen (decimate by 2048, with an FFT size of
4096).  Baudline has a high-precision frequency measurement function
that has the potential of uHz resolution (it uses phase measurements
rather than just FFT bins).

Bottom line -- when I started the test half an hour ago, the nominal
11,025Hz signal showed as 11,024.33235 and right now, it shows as
11,024.33228.  While that doesn't say anything about the long term
stability, it's consistent with what I've observed over a year or more
with this card; frequencies consistently read a little bit low, but
never by more than a fraction of a Hertz.

Now, this card is in a computer that's powered up 7x24 and has been
running for months, so it's in an electrically and thermally stable
environment.  Results from a cold start might be different.

73,
John



ecellison said the following on 11/22/2005 05:16 PM:
> John
> 
> Thanks for the input. I have not heard of anyone else using the external
> reference, and you never noted any severe adverse effects. Is the 5065a
> keeping the SDR dead on, which is the primary objective in this whole
> discussion. Do you notice variation due to the Sound card clock? Perhaps all
> the theory we have been gumming about is not that important in practice.
> 
> If you have to measure the difference on a high quality counter.. er well.
> Also thanks in advance for the tests.
> 
> Thanks!
> 
> -Original Message-
> From: John Ackermann N8UR [mailto:[EMAIL PROTECTED] 
> Sent: Tuesday, November 22, 2005 8:35 AM
> To: ecellison
> Cc: 'Ross'; FlexRadio@flex-radio.biz
> Subject: Re: [Flexradio] Frequency calibration etc
> 
> ecellison wrote:
> 
>>Ross
>>
>> 
>>
>>Well, I think we are a ways away from a kit. I was sort of suggesting that
>>we try just using the Rockwell - Jupiter board and it's 10 mhz oscillator
>>'naked' and just see what we get. In 2 lengthy arounds on this thread
> 
> mostly
> 
>>what we have is theory and nothing tried at this point. I think that John
> 
> -
> 
>>N8UR is the only one I have heard about who is using an external 10 mhz
>>reference to the SDR. 
>>
>> 
>>
>>Comment John? Anyone else using Geralds mod kit with external reference?
>>Results?
> 
> 
> Yes, I've been using my SDR-1000 with external reference from an HP 
> 5065A Rubidium frequency standard.  I haven't noticed any horrid phase 
> noise problems from the 10MHz to 200MHz multiplication, but I also 
> haven't been looking very hard for them.
> 
> I hope that fairly soon -- perhaps over the Xmas holidays -- I will get 
> temporary access to HP's latest super-duper phase noise measurement box, 
> and one of the tests will be to compare the SDR-1000 with original 
> crystal versus the external reference.  I'll certainly post those 
> results when I have them.
> 
> 73,
> John
> 
> 
> 

Re: [Flexradio] Frequency calibration etc

[John Ackermann N8UR]

Mike King - KM0T wrote:

I too have been using an external 10 MHz source on my SDR.

First I used a Rubidium source off of ebay, never noticed anything different 
from the internal crystal other than no drift.  (rock solid)


Note that I have only used it on 902 thru 24 GHz - where the SDR is the 28 
MHz IF.


I recently switched the 10 MHz source to the HP Z3801 GPS receiver.  I A/B 
switched the Rubidium and Z3801A back and forth and could tell no difference 
in the audio.  However when I used the waterfall display while doing the 
switching, the Rubidium source show a bit of light white noise on the screen 
(where I adjusted it) as the waterfall was moving (it was very slight).  The 
10 MHz Z3801A source seemed to eliminate this.


I am not experiencing anything drastic that would indicate the improper 
reception or weak signals covered up while using these 10 MHz sources, but I 
have no way to measure phase noise, just a gut feel for how my system is 
operating on the UHF/SHF bands.


The small rubidiums aren't known for low phase noise (and some of them 
actually impose FM on the signal), so you might see an improvement when 
using the Z3801A which has a very low phase noise crystal.  That might 
explain the difference you saw.  Any electrically steered oscillator is 
subject to increased phase noise from noise on the steering signal, but 
the Z3801A seems to be pretty good.


John

Re: [Flexradio] Frequency calibration etc

[John Ackermann N8UR]

ecellison wrote:

Ross

 


Well, I think we are a ways away from a kit. I was sort of suggesting that
we try just using the Rockwell - Jupiter board and it's 10 mhz oscillator
'naked' and just see what we get. In 2 lengthy arounds on this thread mostly
what we have is theory and nothing tried at this point. I think that John -
N8UR is the only one I have heard about who is using an external 10 mhz
reference to the SDR. 

 


Comment John? Anyone else using Geralds mod kit with external reference?
Results?


Yes, I've been using my SDR-1000 with external reference from an HP 
5065A Rubidium frequency standard.  I haven't noticed any horrid phase 
noise problems from the 10MHz to 200MHz multiplication, but I also 
haven't been looking very hard for them.


I hope that fairly soon -- perhaps over the Xmas holidays -- I will get 
temporary access to HP's latest super-duper phase noise measurement box, 
and one of the tests will be to compare the SDR-1000 with original 
crystal versus the external reference.  I'll certainly post those 
results when I have them.


73,
John

Re: [Flexradio] Frequency stability

[John Ackermann N8UR]

Hi Eric --

The frequency wander seems to be the result of the Reflock II steering
step size.  Since Luis hasn't yet published the VHDL code that drives
the Reflock, we're only guessing, but it appears that the noise occurs
when the frequency is around the midpoint between two steering steps.
The result is that the output bounces between the upper and lower steps.
 I suspect this because sometimes the thing will quiet way down and have
an order of magnitude better stability, then it will start wobbling
again.  If this is what's happening, it should be possible to modify the
code or the hardware to improve this characteristic.

The GPS signal does wander around somewhat, and on top of that the
receivers all contribute their own noise in the 50-100ns range.  That's
why you need to average the GPS signal over quite a time period (1000
seconds or more) to get really good results.  However, for use at HF or
VHF you can get away with shorter averaging times.  Again, we don't know
quite what is in Luis' code, but I suspect he's averaging over 60
seconds or so.

73,
John

ecellison said the following on 11/20/2005 09:44 AM:
> John
> 
> Thanks! The daughterboard sounds ideal for what a lot of us want for the
> SDR-1000. Is the frequency error you mentioned possibly due to the
> introduced small error in the GPS timebases? I know that in the QST article
> (can't remember the name) that there was a cyclic and random error from the
> satellites. Although I seem to recall that it was temperature changes in the
> shack where he was testing. If it's predictable, probably can be eliminated
> in software.
> 
> I really like the fact that it has an I2C interface, since there are a few
> of us just getting started with the Cyclone FPGA in the Xylo board. One of
> the ideas was to use an NCO but with I2C we can talk with the Refloc II on
> the same bus, and the Reflock II is a jewel in the center of the crown of
> getting really accurate with the SDR-1000!
> 
> http://www.fpga4fun.com/board_Xylo.html
> 
> I included Steve, Tim and Tom in another message, since they were major
> contributors in the first discussions. I think this go around should produce
> the ideas to glue it all together into a working device. I'm a little shaky
> on the fine pitch stuff myself and may wait to order the Reflock until you
> have an assembled kit.
> 
> Thanks to you and Steve and others for this fine production from TAPR. Gess
> you can sit back and relax now that someone else is in the saddle! (smile)
> Fat chance!
> 
> Eric2
> 
> 
> -Original Message-
> From: John Ackermann N8UR [mailto:[EMAIL PROTECTED] 
> Sent: Sunday, November 20, 2005 9:10 AM
> To: ecellison
> Cc: 'Guy Atkins'; FlexRadio@flex-radio.biz; Steven Bible
> Subject: Re: [Flexradio] Frequency stability
> 
> Hi Eric --
> 
> Yes, the Reflock II is now shipping as a kit, though it requires fairly
> fine-pitch SMD soldering.  We'll have an assembled and tested version
> available as soon as we can get the contract manufacturer lined up.
> 
> I've done some tests of the Reflock II using a GPS 1pps steering an eBay
> surplus TCXO, and the performance is quite good.  It's not the equal of
> a more sophisticated GPS disciplined oscillator like the surplus Z3801A,
> but it holds within parts in 10e9 (e.g., about +/-25Hz at 10GHz).  The
> only downside is that the frequency error isn't a slow ramp, but rather
> looks like noise with a peak-to-peak period of a few seconds.  At HF or
> even multiplied up to VHF, that's not going to be noticeable.  But it
> bugs me, and we're working to see if there's a way to fix it.
> 
> NOTE: I haven't measured to see if this effect occurs when using an
> oscillator, rather than GPS, as the reference.  I strongly suspect that
> you won't see this when locking to an oscillator, because the loop
> design is very different in that case.
> 
> TAPR is planning to offer a daughterboard to go along with the Reflock
> II that will provide a good quality 10MHz oscillator to serve as the
> reference, and a low jitter VCXO running at 100MHz to drive the
> SDR-1000.  You'll be able to bypass the 10MHz oscillator and use your
> own, or use GPS, if you'd like.  I'm not certain just when the
> daughterboard will be available, but I know that Steve Bible, N7HPR, has
> been working on it.  (By the way -- the same daughterboard, with a
> different VCXO, will also drive the Matt Ettus USRP software radio board.)
> 
> 73,
> John
> 
> ecellison said the following on 11/20/2005 06:24 AM:
> 
> 
>>We have gone around in circles a number of times on this subject and it is
>>still on my 'project mentoring' 

Re: [Flexradio] Frequency stability

[John Ackermann N8UR]

Hi Eric --

Yes, the Reflock II is now shipping as a kit, though it requires fairly
fine-pitch SMD soldering.  We'll have an assembled and tested version
available as soon as we can get the contract manufacturer lined up.

I've done some tests of the Reflock II using a GPS 1pps steering an eBay
surplus TCXO, and the performance is quite good.  It's not the equal of
a more sophisticated GPS disciplined oscillator like the surplus Z3801A,
but it holds within parts in 10e9 (e.g., about +/-25Hz at 10GHz).  The
only downside is that the frequency error isn't a slow ramp, but rather
looks like noise with a peak-to-peak period of a few seconds.  At HF or
even multiplied up to VHF, that's not going to be noticeable.  But it
bugs me, and we're working to see if there's a way to fix it.

NOTE: I haven't measured to see if this effect occurs when using an
oscillator, rather than GPS, as the reference.  I strongly suspect that
you won't see this when locking to an oscillator, because the loop
design is very different in that case.

TAPR is planning to offer a daughterboard to go along with the Reflock
II that will provide a good quality 10MHz oscillator to serve as the
reference, and a low jitter VCXO running at 100MHz to drive the
SDR-1000.  You'll be able to bypass the 10MHz oscillator and use your
own, or use GPS, if you'd like.  I'm not certain just when the
daughterboard will be available, but I know that Steve Bible, N7HPR, has
been working on it.  (By the way -- the same daughterboard, with a
different VCXO, will also drive the Matt Ettus USRP software radio board.)

73,
John

ecellison said the following on 11/20/2005 06:24 AM:

> We have gone around in circles a number of times on this subject and it is
> still on my 'project mentoring' list of things to design collectivly.
> Depending on how much we have to spend, the best bet looks like TAPR Reflock
> 2 which has finally been offered as a kit for about $110 and can be slaved
> to GPS or a high accuracy 10 mhz TC(VC?)XO and produce accurate 100 - 250
> mhz standard avoiding the phase shift by multiplying up from 10 mhz. We have
> not hashed this out lately.
> 
>  
> 
> http://www.tapr.org/kits_reflock_ii.html?PHPSESSID=f42b43a04fcded6a42ced6193
> 4840545
> 
>  
> 
> Perhaps John N8UR can comment on a complete design using the Reflock-2, and
> 1 pps GPS.

Re: [Flexradio] Slightly Off-Topic

[John Ackermann N8UR]

Gary Schmidt W5ZL wrote:


Bottom line, I *WILL* buy Linksys products in the future.


Drifting things even further off-topic. another reason to support 
Linksys is that many of their products (in particular, the ubiquitous 
WRT-54G wireless router) run Linux, and the source code for virtually 
all the firmware is available.  Because of that, several folks have come 
up with new firmware for the WRT-54G that ranges from enhanced versions 
of the standard Linksys code, to completely independent Linux distributions.


I'm running two WRT-54G units with the "OpenWrt" firmware, and while I 
haven't done any of these goofy things with them (yet), it's cool to 
know that I could run a web or ftp server, hook up a weather station or 
webcam, run VoIP, or do who knows what else on these little $69 boxes. 
They even work as access points. :-)


John

Re: [Flexradio] Well written article about SDR importance

[John Ackermann N8UR]

Eric Wachsmann - FlexRadio wrote:

>It has been brought to my attention that our own Dr. Frank Brickle
>(AB2KT)  has written an article describing why SDR technology is
>important.  It is an easy read, and is well written with clear points
>for even the "technology challenged."  Well done Frank.
>
>http://www.groklaw.net/article.php?story=20050916105216639
>  
>

Superb article, Frank!  I follow Groklaw closely and saw the original
article that inspired Frank's post; I wondered if anyone would follow up
on it.  I gave the idea some thought, but I'm glad I procrastinated
because Frank did a far better job than I could have.

73,
John

Re: [Flexradio] Ext. Reference clock kit

[John Ackermann N8UR]

Tim Ellison wrote:

 Reflock II info:

http://gref.cfn.ist.utl.pt/cupido/reflock.html

Cost is going to be near $1000

http://www.tapr.org/products.php


You caught us... the Reflock II is going to fund the next TAPR board 
retreat in the Bahamas. :-)


Actually, the prices are placeholders because we don't have them quite 
finalized yet (and we haven't officially announced availability); in 
particular, we don't have a final quote from the assembly house for the 
partially assembled and fully assembled versions.  The Reflock has one 
fine pitch IC that's beyond what most hobbyists will be willing to 
tackle, so we'll be offering bare board only, complete kit with the IC 
soldered down, and assembled and tested versions.


Think more in the $100-200 range (low end of that for the kit, higher 
end for assembled and tested).


John

Re: [Flexradio] Ext. Reference clock kit

[John Ackermann N8UR]

All --

Just FYI, TAPR is working not only on the Reflock II, which can phase 
lock virtually any oscillator with a DC control voltage to either 
another frequency source, or to a 1pps from a GPS, but also an auxiliary 
board specifically designed to work with the SDR1000.  It will provide a 
low-phse-noise 100MHz oscillator as well as an optional 10MHz TCXO to 
serve as reference (if you have a 1pps source, or other frequency 
standard, you can use that instead).


The Reflock II will be shipping within a few weeks (we hope to have them 
for sale at the ARRL/TAPR Digital Communications Conference in Santa 
Ana, CA on Sep. 23-25).  The SDR-1000 accessory board is just going into 
prototype but it's a pretty straightforward project so hopefully won't 
take too long to get ready for production.


73,
John


Jim Lux wrote:

At 05:53 PM 9/6/2005, ecellison wrote:


Jim

I knew i could bait you! (smile). I am sort of 'gobbled up' by this 
precision thing! I do have my GPS receiver and am ready for the 1 part 
to the -13 (give or take a couple of exponents!). Can we take the 200 
mhz standard out of the SDR 1000 as is? Actually I visit WWV 
frequently with the phase display, from 20 meters, where I been 
operating, and am actually pretty pleased with the long term accuracy 
of the radio. Course I fall asleep and leave it on.


Eric




You can skin that cat a number of ways.

One way: pick off a sample of the 200 MHz and run it into a suitable 
divider/counter widget (like the one Brooke Shera described a few years 
back). Adjust in software


Second way: Get a 200 MHz source that has a "steering input" and use it, 
instead of the 10 MHz source in a Z8301 type unit (or Brooke Shera's 
board).  You could drive a divide by 20 with the 200 MHz source and use 
it in a system designed for 10 MHz unchanged.


Third way: Get a high quality 200 MHz phase locked source and lock it to 
your 10 MHz source.  ( you might be able to do this with an HP 8640..and 
used 8640s are cheaper than brand new 200 MHz phase locked sources)


Fourth way: Measure the DDS output frequency against the 1pps or the 10 
MHz, and calculate from there.  You could either calculate a correction, 
and retune the DDS (but that might screw up the spur minimization 
techniques), or feed that into the IF processing in the software.


Fifth way: Generate a comb from your stable reference, making sure that 
the comb spans the frequency bands you'll tune over.  In software, find 
the comb, subtract it out, and use it to calibrate the rest.  This is 
like using a crystal marker generator to calibrate your analog dial.


The latter is what I'm doing at work, and I'll have a publically 
releasable descriptionof the details in a month or so. Suffice it to say 
today that we calibrate an arbitrary number of free running SDR1Ks and 
their PC sound cards to several ppb, including phase, especially if 
temperatures are reasonably stable.





 James Lux, P.E.



Spacecraft Radio Frequency Subsystems Group
Flight Communications Systems Section
Jet Propulsion Laboratory, Mail Stop 161-213
4800 Oak Grove Drive
Pasadena CA 91109
tel: (818)354-2075
fax: (818)393-6875




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Re: [Flexradio] Well blast it

[John Ackermann N8UR]

Robert McGwier wrote:

> It appears that when the setup panel was reconfigured so that we would
> not have
> scrolling for the DSP panel, that somehow the control for semi-breakin
> has been
> messed up.  The control is there,  and in the parallel port polling
> thread, it is being
> calculated.  But I agree, it is not changing things.  It is the
> default which I find
> comfortable and so I never changed it when "testing".
>
> I am sure Eric can fix it in a few minutes.  Expect 1.4.1 early!
>
> Bob


Hi Bob --

In 1.4.0 I still noticed a missing first dit at about 25WPM.  At 20WPM,
it didn't seem to happen, though I didn't test exhaustively.  I'm using
the USB cable and wonder if that might be a factor?

John

Re: [Flexradio] Frequency Accuracy

[John Ackermann N8UR]

Jim Lux wrote:

> At 07:22 AM 7/5/2005, Frank Brickle wrote:
>
>> Jim Lux wrote:
>>
>>> Seems that a better way to measure clock accuracy on the sound card
>>> is to generate a sine wave in software and run it out to the
>>> (external reference locked) counter.
>>
>>
>> The spotting tone function in the DSP will generate a continuous
>> sine, at an arbitrary frequency, with the CORDIC oscillator function
>> used everywhere in the system.
>
>
>
> There you go, then... Fire up the spotting tone at some convenient
> frequency, run the audio output from the Delta 44 into your counter,
> and directly measure the clock rate.  The ideal frequency would depend
> on your type of counter (straight gate or ratiometric, for instance).
>
I'll do that (as well as measuring a recorded signal to bypass any
contribution of the output process)..

But I still don't understand what was wrong with the original test.  The
question I was trying to answer was how much the soundcard contributed
to the frequency accuracy of the SDR1000 system.  The answer I got is
based on exactly what happens in real use -- with the radio tuned to
X.XXMHz (using an external DDS reference to reduce that error
essentially to zero), a signal at X.XXMHz should yield a 600Hz output
tone.  If it doesn't, there's an error.  That's what I was trying to
quantify.  While the actual sampling rate of the sound card is
interesting, what's more important is its impact on the receiver system
as a whole.

By the way, Bob -- thanks for noting the spur reduction issue.  For my
tests, I had spur reduction on as that's the way the radio is typically
used.

John

Re: [Flexradio] Frequency Accuracy

[John Ackermann N8UR]

Jim Lux wrote:

>
>
> Consider two RF carriers, at 10.001 and 10.002 MHz
>
> If the DDS is perfect, at 10 MHz, and the sampler is perfect, at, say,
> 10 kHz, then you'll get two sine waves in the digitized sequence. One
> at 10 samples per cycle (the 1kHz audio) and the other at 5 samples
> per cycle (the 2 kHz audio).  The ratio between the two will be 1:2
>
> If the DDS is off, but the sampler is perfect, then, both RF
> frequencies will be shifted by the same amount.  Say the DDS is at
> 9.999 MHz (a kHz low).  the two audio frequencies will be 2 and 3 kHz,
> instead of 1 and 2 kHz, so your sampled data stream will have a 5
> samples/cycle (the 2 kHz) and a 3.33 samples/cycle (the 3 kHz). The
> ratio is nolonger 1:2 but something else (5:3.33)
>
> If the DDS is perfect, but the sampler is slow (say at 9kHz, instead
> of 10 kHz), then you'll get two signals at 1 and 2 kHz, but the
> sampled data stream will have a tone at 9 samples/cycle and one at 4.5
> samples/cycle. The ratio is 1:2, but the actual value is different.
>
> The effect is the same as the difference between playing a tape fast
> or slow (which preserves the harmonic relations, even if the pitch
> changes) and tuning high or low with SSB (which does not).

And this is where I'm confused.  I'm not (for this experiment) looking
at the linearity of the passband, but rather the absolute accuracy of
the frequency transformation.

The change in pitch is what I'm measuring -- if everything is perfect, I
know that an input precisely on the frequency the radio is tuned to will
yield an output (audio tone) that's precisely 600Hz.  If the sampling
rate is off, the 600Hz tone will be off, which translates into a
frequency error -- if the tone is 599Hz, that's the same as the radio
being tuned 1Hz low in frequency.  That's the frequency error I'm trying
to measure.

John

Re: [Flexradio] Frequency Accuracy

[John Ackermann N8UR]

Jim Lux wrote:

>
> So this uses the SDR1000 as a audio frequency generator, right?  The
> Delta 44's not in the picture at this point, or if it is, it's
> basically digitizing and playing back at the same sample rate.
>
Hi Jim --

I'm not sure I follow.  If the soundcard is not clocking at the rate the
DSP software assumes it is, the software's understanding about what
frequency it's dealing with will be off by that error.  Think about the
extreme case -- the soundcard is sampling at 24ksamples, while the
software processing the bitstream thinks the sample rate is 48ksamples
(forget about underrun problems for the moment).  That's going to result
in a 1kHz input being presented to the DSP layer as a 2kHz signal.  That
will result in all sorts of possible errors as the signal is
downconverted and otherwise processed.  (Remember, there is a digital
downconversion in the DSP layer; the input to the soundcard is the IF at
11.025kHz).

We're talking about much smaller errors here (maybe parts in 10e5), but
the impact is the same -- an error in sample rate will cause the DSP
code to think the frequency is slightly different than it actually is,
and that will result in an erroneous output signal.

The fact that we're using the same soundcard (and therefore the same
clock) for both sampling and playback complicates the picture, but since
the playback frequency is digitally mixed down from the input frequency,
the two operations aren't likely to cancel each other out because the
error will scale across that 20 to one frequency range.

Or am I missing something?  I'm not a DSP (or for that matter, any kind
of) engineer, so I'm sure I haven't used the right terminology, but
hopefully you can understand what I'm trying to say.

John

Re: [Flexradio] Frequency Accuracy

[John Ackermann N8UR]

ecellison wrote:

> However, there is so much going on in the SDR-1000 and PowerSDR software
>world there are too many projects all at once! It may take till the end of
>the year to get a lot done on this. I am gathering hardware and looking
>forward to the Reflock 2, but would like to see it run native at 200 mhz to
>supply to the SDR. Could also use a DDS at 200 mhz, corrected at 200 mhz.
>Will need some USB glue pieces to get it all together with the project that
>Phil - VK6APH and others are working on. 
>  
>
I should have reported this earlier, sorry -- in theory, the Reflock II
should work at 200MHz without any problems; of course we'll need to find
a decent 200MHz VCXO for it to drive.

John

[Flexradio] Frequency Accuracy

[John Ackermann N8UR]

Following up the conversation a week or two ago about frequency accuracy
in the SDR-1000, I did a test today that may shed some light on the
contribution of the soundcard clock to the error budget.  I used a Delta
44 that I got from Gerald a couple of weeks ago, so it's recent
production.  I used beta 1.3.13.

The short story is that I measured the tone coming out of the radio when
receiving a CW carrier on a known frequency to see how far it deviates
from the nominal 600Hz offset.  The answer is that the error was about
0.27Hz, and was not frequency dependent -- it was essentially the same
on 160M as on 10M.  The sign of the error changed between CW-L and CW-U,
but the amount remained the same.

So, the bottom line is that the Delta 44 has a pretty accurate clock,
and may contribute much less than 1Hz of frequency error.  And, the
error is fixed and doesn't scale with frequency, but does invert with
sideband.

(Of course, this is based on a sample size of one card, but some time
ago I measured another, older, Delta 44 using a different technique and
came up with similar results, so I suspect these are typical results.)


More details on the test:

My SDR-1000 used an HP 5065A Rubidium frequency standard as its external
reference.  The Rb is known to be within about 1 part in 10e12 versus
GPS. (that's an error of 1uHz at 1MHz).

I injected an accurately known frequency into the SDR-1000, put the
radio in CW-U mode with a narrow filter, and then read the audio output
frequency on a high-resolution counter.  The input signal was about
-70dBm and came from a low-noise synthesizer with no (intentional)
modulation.  The synthesizer was referenced to an HP Z3801A GPS
disciplined oscillator, as was the counter.  The Z3801A is also normally
within about 1 part in 10e12 of GPS.

At 1.801MHz, using CW-U and a 25Hz filter, the audio output was
599.712Hz.  At 28.601MHz, with the same conditions, the audio output was
599.739Hz.  In both cases, I averaged for 10,000 single-gate samples. 
The standard deviation in each case was about 0.3Hz.  Averaging the two
results and applying a bit of windage, the offset is about 0.27Hz.

Changing to CW-L gave the same error, but the tone was slightly above,
rather than below, 600Hz.

All the gear, including the PC and Delta 44, had been powered up for a
couple of days, so should have been thermally stable.  The ambient room
temperature was around 73 degrees.

73,
John

[Flexradio] Another 1.3.13 CW datapoint

[John Ackermann N8UR]

I was playing this morning and discovered something that I don't think I
saw mentioned here before.

First, like others have reported, the old keyer in 1.3.13 seems to be
broken.  It keys, but there's no power output.

So, I was playing with the new keyer.   I found that after sending
perhaps 6 dahs at 25wpm, the power output suddenly dropped to near
zero.  The "High SWR" indicator did not come on.

My unit has the antenna tuner installed, and when I used the control to
bypass the tuner, the power drop went away and I could send for as long
as I wanted with the power output holding up.  (I was testing on 10M,
where my vertical has a <2:1 SWR without the tuner.)

So, add the ATU as another possible factor in the CW problems...

73,
John

[Flexradio] Using PowerSDR over VNC

[John Ackermann N8UR]

Just wanted to pass on my display hack...

My main hamshack computer runs Linux, and while I'm patiently awaiting
the SDR-1000 Linux software to grow up, I'm running a separate Win2k box
to run the PowerSDR software.  I don't have room at my desk for a second
monitor, though, so I control the Windows box from the Linux machine via
VNC (virtual network computing).  A VNC server runs on the Win2k
machine, and I open a VNC client on Linux to let me see and control the
Windows desktop (sort of like PC-Anywhere).  The radio audio doesn't go
over the  network, just the screen and mouse/keyboard control.

It works quite well.  Both machines are 2GHz class (the Windows box is a
2.4GHz Pentium IV, and the Linux machine an Athlon 2200+) and the
network between them is 100mbit with a switched hub.

The spectrum and panadapter displays work quite well with almost no
jagginess in updates.  With either of those displays running, the CPU
usage runs around 60-70 percent.  The waterfall display uses much more
CPU, and is usually up in the 90s.  Turning off the spectrum display
drops the usage to 25 percent or so.

Clicking on controls and tuning with the mousewheel gives virtually
instantaneous results.  In particular, tuning with the mousewheel is
very smooth.

Anyway, it's very workable and I don't feel any major disadvantage
controlling the radio this way versus sitting directly at the Windows
console.  So, if you have more computers than desktop space, you might
want to give this a try.

73,
John

[Flexradio] Mic Audio settings

[John Ackermann N8UR]

After a bit of repair and upgrading at Flex-Radio Central, I just fired
up my radio (with amp and tuner) today, and actually talked to someone
on 20 SSB!

I'm using a D44 card without an external mic preamp, and at the moment
just a cruddy hand mike I had around that happened to be wired to work
with the front panel mic connector.

I know a month or so ago there was conversation about using the D44
without a preamp on the mic input.  I found that by setting the preamp
gain on the TX panel to about 35, I get what seems to be decent audio. 
But I'm not sure how that interacts with the "Mic" setting on the main
panel, and I'm not sure how to set the various levels to optimize the
transmit audio (not looking for hi-fi right now, just proper levels and
a bit of compression to add some punch).

Any suggestions for how to optimize the TX audio chain, and particularly
how to balance between preamp setting and front-panel Mic gain
settings?  Any hints on compressor/compandor setting would also be
appreciated.  (I'm running beta 1.3.12).

Thanks,

John

Re: [Flexradio] Many Digests Per Day

[John Ackermann N8UR]

Eric, if you go into the list adminstrator pages and click on "Digest
Options" you can set the size (in kB) that triggers when a digest is
sent, and also an override ("digest_send_periodic")  to send a digest
daily even if the trigger size isn't met.  So, by setting the trigger to
a large value you can reduce the number of digests per day, and by
turning on the other option, you can make sure that at least one goes
out per day.

73,
John


Eric wrote:

>The digests apparently are sent when the amount of data (messages in
>bytes) reaches a certain amount, rather than simply sending once a day.
>This is something I found strange about the setup, but didn't see an
>option to make it daily, weekly or otherwise.  If anyone has experience
>setting up mailman software, please chime in and point out the hidden
>option for us.  We are relatively new at being Reflector admins.  ;)
>
>Eric Wachsmann
>FlexRadio Systems
>  
>

Re: [Flexradio] Rockwell - Jupiter

[John Ackermann N8UR]

n4hy wrote:

Luis Cupido has produced a widget that I believe TAPR is going to offer. 
Steve Bible,
whom you have been communicating with can talk about this. John 
Ackemann, TAPR
prez is an SDR-1000 owner and is a time and frequency freak as well. 
Cupido's widget,
called a Reflock board (I have built four of the originals) uses this 
1pps, 1 pps,
signals to tame oscillators in frequency. The Reflock II will have 
signifiantly extended
tuning range. Ideally, we want to tame a 200 Mhz oscillator. I am not 
certain the
Reflock II is capable of 200 Mhz (it may be) but I am absolutely certain 
that it can do
100 Mhz and a doubling in the DDS will be a significant improvement on 
the factor of

20 we now use with a 10 Mhz injection.

If you want to have a real impact on the SDR-1000, it is my strongest 
possible suggestion
that we use 100 Mhz if we can't get 200 Mhz and that we tame the 
oscillator with the Reflock II

and GPS input.


[ snip ]

My only message is that we should not reinvent the wheel. If the 
solution already exists (such
as Reflock II) then we should use it. If TAPR needs help getting the 
Reflock-II out, then

we should help.


Thanks for the plug, Bob.  The Reflock II is making very good progress, 
and the primary gating point right now is availability of the CPLD 
device; it's brand new and isn't shipping in quantity yet.


The Reflock II might be able to do 200MHz directly; we'll have to try it 
and see.  I know the goal was to go to at least 180MHz.  However, it 
will be possible to put a prescaler on the board and with that 200MHz 
will be a breeze.


One question though -- the DDS in the SDR-1000 can internally multiply 
the reference signal.  I'm currently feeding mine with 10MHz from an HP 
Rubidium standard (as Bob said, I'm a 'time-nut') and it works just fine.


I suspect, as Jim Lux mentioned a while ago, that the answer may be 
phase noise, but can we quantify the tradeoffs between using an external 
200MHz oscillator versus using the chip's multiplier and driving with a 
lower frequency source?


John

Re: [Flexradio] Frequency Calibration.

[John Ackermann N8UR]

[EMAIL PROTECTED] wrote:

>The current cal scheme is unlikely to ever work well for most users. The
>issue
>is the error in the oscillator in everyone's sound card. Without taking this
>into
>account, most of us can achieve very good accuracy at one WWV frequency
>but will find it is way off on another. My sound card was several hundred Hz
>off (at 24 MHz). Unlike the DDS error correction, it does not scale with
>tuned
>frequency. I think this is on Bob's list of things to look at.
>
>Mike W3IP
>  
>
I'm not sure I follow why the sound card error would result in accurate
results at one RF frequency but not another.  Error in the sound card
clock is like an error in the last local oscillator -- it generates a
constant offset that doesn't change with frequency.

For what it's worth, the clock in the Delta 44 card (at least mine)
seems to be very good.  I have used a Delta 44 to drive a spectrum
analyzer program under Linux for the last three ARRL frequency measuring
tests, and I do frequency comparisons (between a pilot frequency and the
unknown signal) with milliHertz resolution.  While I haven't done phase
noise tests, I've measured a precise reference tone, and the frequency
accuracy over periods of tens of seconds to tens of minutes is very good
-- at 1kHz, down in the 0.00x Hz range (i.e., parts in 10e-6, about what
you'd expect from a good quality crystal).  Since that's a direct offset
that's not multiplied, the sound card's contribution to the RF frequency
error is pretty minimal.

Despite those results, my goal is still to have the whole frequency
chain stabilized.  One thing I've thought about is hardware hacking the
Delta to use an external clock.  I haven't dug into that possibility
yet.  Several of the other M-Audio allow an external "word clock" which
the pro audio world uses to lock the sampling rates of multiple cards.  
It's a shame that feature isn't on the Delta 44 as it would allow an
easy way to use an external reference.

John