GPS Disciplined Oscillator

[Loren Moline WA7SKT]

Hello,

I am still working on the above subject using a cheap GPS receiver. Does anyone else have this on their some day radar? If you do I will keep you posted on my findings.

This is proving to be an interesting project. 

Loren Moline

WA7SKT

[Mark Spencer]

I've dabbled with this but mostly bought used GPSDO's via eBay or inexpensive Evaluation type boards. I also purchased one of the Miller / G3RUH GPSDO's that I still use during my portable roving / ops. I also have a Jackson Labs Fury GPSDO that I don't use much these days.

I also tried disciplining a Rb oscillator from a GPS. It didn't really work well ienough vs my better GPSDO's that used normal crystal oscillators to be worth the trouble in my view.

Somewhere I have a Jupiter GPS board in my junk bin awaiting a future project. I'd be curious what you come up with.

I'm mostly into connecting modules together and wrting computer programs these days vs component level construction.

73
Mark S
VE7AFZ

[Stephen Hanselman]

I have blank boards that take a single 10mhz input and split/amplify it to 6 outputs. It does use a pricy part a mini-circuits 6 way splitter

Regards,

 

Stephen Hanselman, KC4SW

Datagate Systems, LLC

3107 North Deer Run Road #24

Carson City, Nevada, 89701

(775) 882-5117 office

(775) 720-6020 mobile

s.han...@datagatesystems.com

www.datagatesystems.com

a Service Disabled, Veteran Owned Small Business

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[Loren Moline WA7SKT]

One of the things that this GPS receiver offers is an output up to 10MHz for locking an OCXO to. I think I may use 1 MHz which should be cleaner than the 10MHz and this will reduce the divider chain to just a /5 and a

/2 as opposed to having to divide down to 10KHz to present to the phase detector along with the 10KHz from the GPS receiver.

Loren Moline

WA7SKT

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From: pnw...@googlegroups.com <pnw...@googlegroups.com> on behalf of Loren Moline WA7SKT <lmo...@hotmail.com>
Sent: Wednesday, October 25, 2017 6:22:05 PM
To: pnw...@googlegroups.com
Subject: [PNWVHFS] GPS Disciplined Oscillator

 

--

[Greg Stahlman]

Did I offer this group any of my GPS boards with the on board 10MHz TCXO?  Can't remember.  They are not as accurate as a RB or Trimble, but at least ±1@ 10^-9.  That’s the best I can test to.

 

Info here..

 

http://www.packratvhf.com/A%20Packrat%20GPS%20Receiver%20Project.pdf

 

From: pnw...@googlegroups.com [mailto:pnw...@googlegroups.com] On Behalf Of Loren Moline WA7SKT
Sent: Wednesday, October 25, 2017 6:22 PM
To: pnw...@googlegroups.com
Subject: [PNWVHFS] GPS Disciplined Oscillator

 

Hello,

--

[Edward R Cole]

Loren,

I think locking a OCXO seems like overkill.  Mine drifts only 1-Hz over a six month period.  Accuracy is +/- 5 E-12.  That is better than my rubidium (+/-5 E-11).  10-GHz is E+12 so that is +/- 5 Hz.  That's pretty good.

73, Ed - KL7UW

73, Ed - KL7UW
  http://www.kl7uw.com
Dubus-NA Business mail:
  dubu...@gmail.com

[Mark Spencer]

I won't speak for Loren but from my perspective one really needs to define what the use case is.

One of the ways I used to evaluate my GPSDO's was to compare them to several very stable OCXO's (two of which have been running un disturbed for years in my basement. The sealed lead acid batteries that provide them with backup power end up being used for my portable ham radio activities over time.)

In essence, at shorter time intervals I considered the OCXO's to be "better" at longer time intervals I considered the GPSDO's to be "better."

All that being said after looking at using a packaged OCXO vs a portable GPSDO as a frequency standard for 1.2 GHz portable work I decided to use the GPSDO. It is also hard to confirm frequency accuracy in the field to the accuracy I want without a reference such as a GPSDO in my experience.

For timing (for FT8 and what not) I'm leaning towards using an OCXO as a clock source for a small time server as I don't have to worry about the GPSDO lossing lock on the satellites at times and I can quickly cross check the timing accuracy against WWV with an acceptible level of accuracy. I expect the OCXO will be more than accurate for a typical contest weekend.

Since I have most of this stuff in my junk box my decision making process may be a bit skewed (

73
Mark S
VE7AFZ