[time-nuts] display on sale

[J.D. Schoedel]

Most of  you like to DIY, but this might be of interest to some.
http://www.symmetricom.com/lp/gbu/email/time-display-promo-landing-page/?emailid=GBU078_NTD_Promo_ProdPg&lead_source=Web

J.D.
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Re: [time-nuts] Why a 10MHz sinewave output?

[J.D. Schoedel]

Hal Murray wrote:

li...@rtty.us said:
  

Thank goodness for that inertia. I can still cable up a 100Kcps sine wave
standard to run stuff from "long ago". When I run into a box that uses a T1
signal for a clock reference - not so easy in the basement. 



How much gear is there that uses T1 for a clock input?

Is there any interest in a board/chip/whatever that converts 10 MHz to T1?  A 
clean design using a decimal DDS should fit into a small FPGA, maybe a CPLD.


  
There  is quite a bit of telecom gear that will take a T1(or E1) as a 
clock reference.  A T1 BITS will provide an all 1's AMI signal which 
looks like 772 kHz on a scope. 


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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Sync...

[J.D. Schoedel]

Quoting from a white paper on their site:
"it uses a tiny hollowed-out silicon cube filled with cesium gas."

On 01/18/11 20:17, paul swed wrote:

Quick question is this a rb reference.
Looked at the symetricom site they never actually say or I missed it.

On Tue, Jan 18, 2011 at 2:37 PM,  wrote:

   

Here is a link to the press release with more technical details and
pictures:

_
http://www.eetimes.com/electronics-news/4212176/Chip-scale-atomic-clock-app
roaches-performance-of-modules-2_
(
http://www.eetimes.com/electronics-news/4212176/Chip-scale-atomic-clock-approaches-performance-of-modules-2
)


In a message dated 1/18/2011 11:32:33 Pacific Standard Time,
bro...@pacific.net writes:

Hi  Mark:

I got the idea that it's a Rubidium clock.

Have  Fun,

Brooke Clarke
http://www.PRC68.com


Mark Spencer  wrote:
 

The long term aging spec is interesting to me, as a cesium  physics
   

package is a
 

primary standard wouldn't there be an ultimate  limit to the total long
   

term
 

aging ?  (I took a quick glance at  the full data sheet and didn't see
   

any
 

reference to  this.)


- Original Message 
From:  Julien Goodwin
To: Discussion of  precise time and frequency
   

measurement
 

Sent:  Tue, January 18, 2011 8:04:20 AM
Subject: Re: [time-nuts] Symmetricom  Launches CSAC Product for Precise
   

Timing
 

and  Synchronization

On 19/01/11 02:35, Pierpaolo Bernardi  wrote:

   

Though this could be of  interest...

  http://www.insidegnss.com/node/2446

 

  "The SA.45s reportedly provides ... short-term stability (Allan
  Deviation) of 2E-10 @ 1 sec, long-term aging of 3E-10/month"

  >   From the data sheet of the bigger Rubidium micro-clocks:

  SA.33/35m:
1 Sec stability-<3E-11
1 month aging - +/1  1E-10

Neat, but only really of benefit to *really*  space/weight/power critical
devices.

"The cesium atoms  are “excited,” or heated to a vapor state by a beam
generated from a  vertical-cavity surface emitting laser (VCSEL) that
passes between  upper and lower polymide heater/suspension strips. The
VCSEL was  designed by Sandia Labs, one of Symmetricom’s partners on the
CSAC  team."

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Re: [time-nuts] DS-1 from 10MHz

[J.D. Schoedel]

Definitely a basement project.
J.D.

Bob Camp wrote:

Hi

A lot depends on weather this is a one off basement project or a commercial endeavor. If it's commercial, there are people who will sell you a packaged part that will do the 10 MHz to T1 conversion. 


Bob

On Jul 4, 2010, at 10:38 PM, Hal Murray wrote:

  

   I would like to generate a DS-1 timing reference from 10 MHz, e.g a
T-bolt.  Thought someone here might be able to suggest a starting point.
  
One approach is a PLL.  You will have to divide 1.544 MHz by 193 and 10 MHz 
by 1250.  If you want to use the TAPR Clock-Block, I think you will need 
something like a divide by 10 between the 10 MHz and the Clock-Block to get 
the numbers within range.


I wonder if you could use a VCXO and fit all the logic in a tiny micro.  It 
would probably need a few external parts to filter the PWM output.  Maybe the 
filtering inside the VCXO would be good enough.



Another approach is to use a DDS.  Analog Devices makes the whole thing in 
one package, but the numbers don't work out exactly.  How close to you need 
to be?  With a 32 bit (binary) adder, you get 1544000.001158 MHz.  With 48 
bits you get 1543999.99989825.


But you don't have to use a binary adder.  You have 1000 Hz and you want 
1544000 Hz, so you need to multiply by 1544000 and divide by 1000.  That 
reduces to 193 / 1250.  So add 193 each cycle using modulo 1250 addition.  
Each time it overflows, kick out a pulse.  If you want a square wave output, 
divide by 625 and toggle the output on each overflow.  That sort of logic 
fits well in a FPGA/CPLD.


That will give you a clock that's locked to your input clock but with lots of 
jitter.  (up to 1/2 clock off in each direction, so 100 ns peak-to-peak)


You can run that through a low pass filter and/or feed the top bits into a 
sine table and on to a DAC.  Note that isn't the standard ROM.  You have to 
make a new table for each modulus and if you are using standard ROMs with 
binary addressing you will waste up to 1/2 of each ROM.


--
These are my opinions, not necessarily my employer's.  I hate spam.




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Re: [time-nuts] DS-1 from 10MHz

[J.D. Schoedel]

Perhaps.  The DS-1 signal has a pulse-mask which is not square.  And 
while the all "1"s AMI signal looks like 772 kHz, presumably the  D4 or 
ESF frame would require some zero's in the 193d bit position.  But your 
suggestion leads to a possible 2 stage solution.  There are CSU/DSUs 
which accept an external TTL level clock.  So perhaps use the tapr board 
to drive the CSU/DSU and let the CSU/DSU build the DS-1 frame.

Thanks,
J.D.

Poul-Henning Kamp wrote:

In message <97416.58969...@web30303.mail.mud.yahoo.com>, Stanley Reynolds write
s:

Couldn't you do the same thing much easier with the ICS525 chip ?

Neat and convenient:

http://tapr.org/kits_clock-block.html

Poul-Henning


  

I have a board that does this, I could send you.

See Pictures here:

www.n4iqt.com/fts4040/ds1
=A0
www.n4iqt.com/fts4040/ds1/FTSds1001.JPG

www.n4iqt.com/fts4040/ds1/FTSds1002.JPG

www.n4iqt.com/fts4040/ds1/FTSds1003.JPG

Stanley



- Original Message 
From: J.D. Schoedel 
To: Discussion of precise time and frequency measurement 
Sent: Sun, July 4, 2010 11:57:44 AM
Subject: [time-nuts] DS-1 from 10MHz

All,
=A0 I would like to generate a DS-1 timing reference from 10 MHz, e.g a T-b=
olt.=A0 =

Thought someone here might be able to suggest a starting point.
Thanks,
J.D.

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[time-nuts] DS-1 from 10MHz

[J.D. Schoedel]

All,
   I would like to generate a DS-1 timing reference from 10 MHz, e.g a 
T-bolt.  Thought someone here might be able to suggest a starting point.

Thanks,
J.D.

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Re: [time-nuts] Advantages & Disadvantages of the TPLL Method

[J.D. Schoedel]

For those of us not up to speed, what is "G8"?
Thanks,
J.D.

gandal...@aol.com wrote:
In a message dated 21/06/2010 06:26:46 GMT Daylight Time,  
sar10...@gmail.com writes:


Well,  Mr. Smartypants, the difference here is that his Snake Oil has
been proven  to work. I don't particularly care how the thing works
mathematically, I'm  more interested in the results. If you want to get
bogged down in the nitty  gritty instead of looking at the big picture
then you are the one loosing  out here.

A respected member of this list carried out tests of this  TPLL
implementation against a  expensive piece of equipment and  found
it produced very similar results over an expected range of  usability
with a lot of different DUT and spending a month doing it. Stop  trying
to extract stuff out of Warren that he has already said he is  unable
to give you. He is an amateur experimental engineer (no  offence
intended Warren) and as such doesn't have, or need, to understand  this
stuff mathematically or in the secret special language that only  the
professional engineering gods know. He has something you don't  have,
he has a $10 gadgit that produces results that are easily good  enough
for many on this list. So it looks like your the looser  here!

 
Whilst it's possible you might have been blessed with inner  secrets hidden 
from us mere mortals, it would seem much more likely  that you're just 
droning the mantras of the master.
 
And if "I got my G8 before you" is in any way important to  you, then I 
find that really sad.
 
Over and out
 
Nigel

GM8PZR
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Re: [time-nuts] Symmetricom 5115A Phase Noise Allen Deviation Test Set on ePay

[J.D. Schoedel]

Do you suppose we should ask if it measures Allan variance or are we 
restricted to Allen variance?

J.D.


Matt Osborn wrote:

On Tue, 6 Apr 2010 19:58:14 +1200, Steve Rooke 
wrote:

  

Time to check under the lounge suite cushions for that spare change :)

230458691424



I really like his 'Floopy Drives'.

-- kc0ukk at msosborn dot com

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Re: [time-nuts] FS: Brandywine GPS-4 - Qty: 7 available - Manual & pics

[J.D. Schoedel]

Scott,
What is the synthesizer output on these?  It appears to be factory 
fixed.  How will you handle orders?
Thanks,
J.D.

Scott A Sybert wrote:
> Hi Everyone,
>  
> Here are some links to pictures of the GPS' and the manual.  I've gotten alot 
> of response from people looking for the manuals and photos.  I appologize for 
> not posting links in my original email.
>  
> Pleass feel free to contact me with any questions or concerns
>  
> http://www.ne900.net/files/GPS1.jpg 
> 
>  
> http://www.ne900.net/files/GPS2.jpg 
> 
>  
> http://www.ne900.net/files/GPS3.jpg 
> 
>  
> http://www.ne900.net/files/GPS4.jpg 
> 
>  
>  
> http://www.ne900.net/files/GPS4_Manual_v2.1.pdf 
> 
>  
>  
> Regards,
> Scott
> KB1FXY
> 978-423-9855
>
> 
>
> From: [EMAIL PROTECTED] on behalf of Scott A Sybert
> Sent: Fri 6/27/2008 8:56 PM
> To: time-nuts@febo.com
> Subject: [time-nuts] FS: Brandywine GPS-4 - Qty: 7 available
>
>
>
> Hi Everyone,
>
> I have a number of Brandywine GPS-4 units available.  They are all NOS pulls 
> from a cancelled project.  They provide a number of outputs including 1PPS 
> and 10MHZ.  If anyone is interested I can email you pictures and a copy of 
> the owners manual.  Price is $400 and that includes USPS Priority shipping to 
> anywhere in the US. 
>
> All units are guaranteed working 100%.  I also have outdoor Panasonic marine 
> antenna kits w/ 90ft coax.  They have a waterproof TNC connecter on the 
> antenna side and a BNC on the GPS side.  These kits are also brand new and 
> the price is $40.  I can bundle them with the shipping on the GPS.
>
> Thanks,
> Scott
> KB1FXY
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>   


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