[time-nuts] Recommendations for a newbie?

[Chris Albertson]

On Fri, Sep 7, 2012 at 10:34 AM, Robert Liesenfeld <xunil at xunil.net> wrote:
> Hello-
>

> I'm considering the purchase of a GPS receiver to serve as my workbench
> 10MHz source.

Buy a Thunderbolt first.  This is I think the best value and
technicaly hard to beat.  These is much support for the t-bolt here.
many people know about them.



> ...I have read that
> a rubidium standard's short-term stability is not as good as a GPSDO, and
> that they're mainly used for holdover - is my understanding correct?  My
> thought is to (eventually) use a rubidium device to stabilize a GPSDO
> should the receiver lose satellite signal.

Hold over is their best use.  But they work well as a portable
standard and if you need something that can work quickly after power
is applied with no need to set up a GPS antenna and wait for a
self-survey.   I is actually very unlikely that the GPS signal will
fail.  This might happen on a cell tower where some transmitter might
fail and jam GPS but it is unlikely at your home.  I think the Rb's
best use is is portable or temporary uses where yo can't set up a GPS.

One more thing.  If your budget were lower you could build a GPSDO
using a $20 GPS and a $20 OCXO plus some "glue" logic and get pretty
good performance for about $100.   The reason to build might be any of
these (1) you want soething that uses very low power (2) you need some
feature like automated failover to Rb on loss of signal, or (3) self
education.

Chris Albertson
Redondo Beach, California