Anderson'; 'Jim Lux'; '[EMAIL PROTECTED] Biz'
Subject: Re: [Flexradio] frequency calibration etc
Can an FPGA
pin actually accept a 10 mhz or 200 mhz signal so that the LE's could be
configured to divide it down?
10 MHz is no problem.
200 MHz! Many FPGAs can handle this frequency, some go
Hello Eric!
Thanks. Well not too difficult to divide the 200 by 10 externally and
perhaps provide buffering for the 200 mhz sig coming out of the SDR.
The EP1C3T100 used in the Xylo board you mentioned earlier is good to
275/320/405 MHz depending on the speed grade of the part. That may be
At 01:56 PM 11/23/2005, you wrote:
Folks
I have a stupid question which I should be able to look up. Can an FPGA
pin actually accept a 10 mhz or 200 mhz signal so that the LEs could be
configured to divide it down?
Yes.. depends on the FPGA, though, what the maximum clock rate
is.
Jim 'rmk
At 02:15 PM 11/23/2005, ecellison wrote:
Lyle
Thanks. Well not too difficult to divide the 200 by 10 externally and
perhaps provide buffering for the 200 mhz sig coming out of the SDR.
Eric2
Even better, if you don't want to give up the resolution (dividing by 10
does that) is divide by 10
a
running average of the last three digits in an accumulator for the
comparison against the 'rock'.
Eric2
-Original Message-
From: Jim Lux [mailto:[EMAIL PROTECTED]
Sent: Wednesday, November 23, 2005 5:44 PM
To: ecellison
Cc: '[EMAIL PROTECTED] Biz'
Subject: RE: [Flexradio] frequency
Relatively prime numbers are your friend.
Jim Lux wrote:
At 02:15 PM 11/23/2005, ecellison wrote:
Lyle
Thanks. Well not too difficult to divide the 200 by 10 externally and
perhaps provide buffering for the 200 mhz sig coming out of the SDR.
Eric2
Even better, if you don't want
At 03:52 PM 11/23/2005, ecellison wrote:
Jim
Could we just not divide at all using the 1 pps gate and just use the
variance of the last 2 or three digits, and make the assumption that it was
accurate 200,000,xxx? I wouldn't think we would want to make any correction
in software more frequently
At 04:09 PM 11/23/2005, Robert McGwier wrote:
Relatively prime numbers are your friend.
Indeed, but I was thinking that one might be able to adopt an off the shelf
dual modulus counter, which typically differ by one count.
Actually, there's all kinds of other strategies, too.. you can use the
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 its 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
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
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
You made the right decision to move from the rubidium. The off ebay
rubidium sources almost all FM the line looking for it. This means
that the output of one of these rubidiums is typically a zero mean on
the frequency of interest and should never be used directly but only as
a reference in
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
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.
Give a look here : http://gpsdo.i2phd.com
73 Alberto I2PHD
And look here too: http://mysite.verizon.net/n1jez/osc/page5.html This
board and Jupiter GPS module are available for $25, but apparently supplies
are limited. A small number of us in the NJQRP club are doing a group
project with it. You can see a close-up photo of a unit we had at the
Awesome Alberto!
That is under an hours work to layout! We need to google and delve more
deeply into our Italian genius' web site!!
Bob
Gollum wrote:
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
Robert McGwier wrote:
Awesome Alberto!
That is under an hours work to layout! We need to google and delve more
deeply into our Italian genius' web site!!
Bob,
I am not the author of the project, it was developed by Andy Talbot G4JNT.
I just hosted it in one of my pages.
I have designed
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
-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Gollum
Sent: Tuesday, November 22, 2005 10:25 AM
To: FlexRadio@flex-radio.biz
Subject: Re: [Flexradio] Frequency calibration etc
Well, I think we are a ways away from a kit. I was sort of suggesting that
we try just using
At 02:16 PM 11/22/2005, ecellison wrote:
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
.
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
At 03:31 PM 11/22/2005, John Ackermann N8UR wrote:
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.
Bottom line -- when I started the test half an hour ago, the nominal
To: ecellison; 'John Ackermann N8UR'
Cc: FlexRadio@flex-radio.biz
Subject: Re: [Flexradio] Frequency calibration etc
At 02:16 PM 11/22/2005, ecellison wrote:
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
I know that Gerald is a distributor since you don't sell M-Audio
products without being one. So I suppose that constitutes a relationship.
Bob
Mark Amos wrote:
You guys have probably already hashed this kind of thing out earlier, but
does anyone at Flex have a relationship with the M-Audio
[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.
.
Regards,
k2ox
-Original Message-
From: John Ackermann N8UR [mailto:[EMAIL PROTECTED]
Sent: Tuesday, November 22, 2005 9:09 PM
To: [EMAIL PROTECTED]
Cc: FlexRadio@flex-radio.biz
Subject: Re: [Flexradio] Frequency stability and calibration
[EMAIL PROTECTED] said the following on 11/22/2005 08:29
: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Jim Lux
Sent: Tuesday, November 22, 2005 5:57 PM
To: ecellison; 'John Ackermann N8UR'
Cc: FlexRadio@flex-radio.biz
Subject: Re: [Flexradio] Frequency calibration etc
At 02:16 PM 11/22/2005, ecellison wrote:
John
Thanks for the input. I
At 02:25 PM 11/21/2005, richard allen wrote:
Ross,
One thing you need to remember
is that the fft bin widths will greatly effect sub 20 Hz accuracy that
you are looking for. Also, the pixel width in the display,
indicating the cursor position, may be many Hz. Of course the sound
card may be
I completely agree with the external oscillator software fix for offset
and I even use it for experiments where I am tuned to 10 Mhz. I can't
figure out how to keep the reference tuned and the signal of interest
tuned with the single IF! Please fix my ignorance.
Bob
Jim Lux wrote:
At
: [Flexradio] Frequency
stability and calibration
Ross,
One
thing you need to remember is that the fft bin widths will greatly effect sub
20 Hz accuracy that you are looking for. Also, the pixel width in the
display, indicating the cursor position, may be many Hz. Of course
.
**
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Guy Atkins
Sent: Sunday, November 20, 2005
12:45 AM
To: FlexRadio@flex-radio.biz
Subject: Re: [Flexradio] Frequency
stability
This site, which I've had bookmarked for a long time,
offers low-priced 10
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
'; 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
At 05:15 PM 11/19/2005, Ross wrote:
Bob,
(and others)
Would making up a 10mhz refence standard and using GPS based timing,
improve the frequency stability of the SDR1000.
If so, suggestions please as to where to obtain or build up a precision
standard.
There's been a bit of discussion about this
; 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
This site, which
I've had bookmarked for a long time, offers low-priced 10 Mhz frequency
standards for homebrewers:
http://www.aade.com/
AADE offers nice
little digital frequency displays, too, for old-tech radios.
The firm is just a
few miles from me, but I don't know if it's an actual
At 06:03 PM 7/4/2005, John Ackermann N8UR wrote:
Jim Lux wrote:
Consider two RF carriers, at 10.001 and 10.002 MHz
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
...If you're looking at the analog output of the sound card,
which is essentially the looped back analog input to the card, then
the sampling rate may not make any difference.
Keep in mind that the SDR-1000 is not baseband in, baseband out, but
uses an IF of 11 to 15 kHz depending on the
Do not forget that you can have two different conditions in your
settings that will impact
your analysis. spur reduction on, spur reduction off. spur reduction
turned off, the
last conversion IN THIS DUAL CONVERSION SUPERHETERODYNE RX
is done by the software oscillator is -11025 Hz.
When
At 03:27 AM 7/5/2005, Robert McGwier wrote:
Do not forget that you can have two different conditions in your settings
that will impact
your analysis. spur reduction on, spur reduction off. spur reduction
turned off, the
last conversion IN THIS DUAL CONVERSION SUPERHETERODYNE RX
is done by
At 10:49 PM 7/4/2005, Lyle Johnson wrote:
...If you're looking at the analog output of the sound card, which is
essentially the looped back analog input to the card, then the sampling
rate may not make any difference.
Keep in mind that the SDR-1000 is not baseband in, baseband out, but uses
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
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
At 09:23 AM 7/5/2005, John Ackermann N8UR wrote:
Jim Lux wrote:
At 07:22 AM 7/5/2005, Frank Brickle wrote:
Jim Lux wrote:
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
John
That really is good news! I am still studying this, and reading. You guys
got me hooked. I think a really accurate long and short term low phase shift
device is do-able at a very reasonable cost 200 bux on a 'put it together
yourself' budget.
However, there is so much going on in the
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
At 12:13 PM 7/4/2005, John Ackermann N8UR wrote:
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
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
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
At 06:17 PM 6/15/2005, James C Samuels wrote:
I have been thinking of this improvement myself and just today noticed
that Mel, K0PFX, suggested it last month with no apparent responses to his
post. Is is possible to have both MHz and kHz decimals in the frequency
display? That is 7.025.125
James - I agree with you that MHz and KHz decimals would be helpful.
John Denson, AI6A
- Original Message -
From: James C Samuels [EMAIL PROTECTED]
To: FlexRadio@flex-radio.biz
Sent: Wednesday, June 15, 2005 6:17 PM
Subject: [Flexradio] Frequency Display Suggestion
I have been
[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.
At 07:46 PM 6/11/2005, [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
At 04:17 AM 6/12/2005, John Ackermann N8UR wrote:
[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
For frequency cal you could use WWV or CHU.
For level cal you can attach a dummy load, and set it to be whatever the
noise floor is supposed to be - think these values are in the docs, as I
recall -120 w/o RFT and -130 with. Of course, it won't really be
calibrated with this approach, it
@flex-radio.biz
Sent: Saturday, June 11, 2005 20:26 PM
Subject: Re: [Flexradio] Frequency Calibration.
For frequency cal you could use WWV or CHU.
For level cal you can attach a dummy load, and set it to be whatever the
noise floor is supposed to be - think these values are in the docs, as I
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