Freq stability, cheap source of]

[Andre' Kesteloot]

Larry Kayser wrote:

> Greetings All:
>
> There is a very cheap source of very high stability reference available to
> everyone.  It is the 1 PPS from almost any second hand OEM level GPS
> receiver.  I have one here that cost $20 US$, about the size of what we once
> called a penny folder of paper matches.  I did a little poking around on the
> Internet over a year ago and found a chap selling Garmin GPS OEM Model 20
> and 25 units complete with the external connector.  The unit I have here
> runs happily on 5V.  The removal of selective availability (SA) last year
> means only the 5% of the time basic jitter is left, references are possible
> to stabilities in a few parts in 10 - 11th.
>
> Brooks Shera published an excellent article in QST on "disciplining" a
> frequency standard to the GPS 1 PPS signal.
>
> see http://www.rt66.com/~shera/index_fs.htm
>
> Hope this might help some find a way to improve stability on LF
>
> Larry
> VA3LK