[time-nuts] GPS W/10KHz

Michael Jensen mriisj at danamps.dk
Sun Feb 9 05:12:02 EST 2014


I have made a design with the 10KHz for usage on the OZ7IGY beacon project,
I can mail you the diagram and support you with a PCB if you so whish :)

http://rudius.net/oz2m/ngnb/gps.htm

It have 2 times 10MHz outputs, the stability is less than 5 mHz.

Designed for Rockwell Jupiter GPS receivers TU30, TU40 and TU60 series

Michael, OZ2ELA 

-----Oprindelig meddelelse-----
Fra: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] På vegne
af EWKehren at aol.com
Sendt: 8. februar 2014 23:50
Til: time-nuts at febo.com
Emne: Re: [time-nuts] GPS W/10KHz

The problem with the PLL analog version is the same as with any digital
GPSDO. The saw tooth is present at 10 KHz just like 1 Hz. To the best of my
knowledge there is no GPS receivers out there for less than $ 1000 with out
saw  tooth. Timing receivers output the correction value and you can either
with  software or a variable delay do correction.
I encourage you to pursue your idea since for more than ten years I had the
privilege to communicate with some of the sharpest minds on that subject and
obviously the missed something. 
That also applies for the three of us that have been working intensely on
developing and testing the next generation of GPSDO's that we hope to
introduce  to time nuts soon.
In the meantime with the ever increasing price of Tbolts,  Shera is  worth a
second look. When we worked on the last code release of Shrea using a Morion
we got consistently better than 1 E-11. Yes some of the IC's are hard to
find and that is why I used more readily available parts and did a new board
layout. 
Also did one using a $ 1.20 Altera gate array.
Bert Kehren
 
 
In a message dated 2/8/2014 12:33:48 P.M. Eastern Standard Time,
albertson.chris at gmail.com writes:

On Sat,  Feb 8, 2014 at 3:44 AM, Volker Esper <ailer2 at t-online.de>  wrote:

>
> you don't need 10kHz to build a GPS disciplined  oscillator. GPSDOs 
> are build with control loop response times in the  range of some 
> hours, so the loop will be absolutely happy with a 1PPS  input.
>


Of course you are correct.  Most GPSDOs are  driven with a 1Hz pulse.  But I
think maybe the OP is not building  just any GPSDO but maybe he is looking
to repair a specific GPSDO that is  designed to use the old (and now rare)
Rockwell GPS.      If  that is the case he needs the old Rockwell or needs
to redesign his  system.

If you are starting from scratch to build a new GPSDO it's  easier now.  All
you need is some kind of a phase detector (74HC4046  ?) and a small uP that
has a good built-in DAC.  The uP checks the  phase once per second and
adjusts it'sDAC accordingly.
-- 

Chris  Albertson
Redondo Beach,  California
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