[time-nuts] GPSDO Component Selection

[Chris Albertson]

On Sun, Sep 9, 2012 at 1:14 PM,  <bg at lysator.liu.se> wrote:

> True for a cheap oem navigation receiver. Not true for a geodetic quality
> receiver, who usually have some options (external frequency input, PPS_in)
> to make them the best timing receivers available. However they are much
> more expensive than the typical single frequency timing reciver.

I looked at every link and can't see where they give a timing accuracy
spec on the PPS with respect to UTC.   Possition accurracy is very
good and we might assume the timing is as good.  But they don't say it
is.  What's interesting is these GPSes will accept an accurate clock
input in order to give better location data.   That is the opposite of
a timing GPS where you tell it accurate location data so that it can
get better timing.   Cutting down the unknown in one lets you do
better in the other.   I assume these all cost well over $50.  You can
get a pretty good timing GPS for $30 and it WILL have the PPS error
specified.

To the OP.  None of this matters a lot because PPS is a standard input
signal.  It is easy to swap out a GPS receiver later.  Same with the
OCXO.  From a control point of view they are all pretty much the same.
 You can swap them out later


Chris Albertson
Redondo Beach, California