[time-nuts] Symmetricom TimeSource 2700
SAIDJACK at aol.com
SAIDJACK at aol.com
Tue May 1 19:12:20 UTC 2012
Hello Mark,
you could connect the Fury 1PPS output to the 1PPS external sync input of
the PRS-10 Rb and let is self-discipline to GPS. Set the Fury 1PPS jumper
JP4 to raw-1PPS (pins 2 and 3), and that will make the Fury GPSDO generate
the raw 1PPS signal from the Motorola GPS receiver albeit without sawtooth
correction. You won't need sawtooth correction if you set the PRS-10 time
constant to say 10,000 seconds.
bye,
Said
In a message dated 5/1/2012 10:55:34 Pacific Daylight Time,
mspencer12345 at yahoo.ca writes:
Sorry to resurrect an old thread, but I thought someone might find this of
interest.
I purchased a 2700 intending to harvest the PRS10. Prior to cracking
open the case I powered up the unit to ensure it was basically working so I
could return it if needed. I noticed that despite not having an antenna
connected it seemed to find and track CDMA signals and after a few hours the
10 Mhz output was in a few parts of 10E-12 of my GPSD0.
After a bit of investigation I found the following
Adding an external antenna didn't seem to make much difference to the
performance.
The 1pps output is approx. 75ms out of sync with the 1pps output from my
Fury GPSD0.
>From time to time the 10 Mhz output experiences phase jumps of several
tens of ns. Manipulating the unit (ie. connecting to the RS 422 port) may
induce this. Power cycling the unit seems to cure the problem and the unit
usually takes an hour or two to re lock. It's possible that the lack of a
proper ground in my instalation may be causing some of the issues as well.
This problem would be a show stopper for me in terms of using this unit
to replace my GPSDO's. I'm not sure if this issue is specfic to my unit or
not.
I've attached some initial ADEV plots showing the typical performance of
the 10 Mhz output vs three of my other references. (I wouldn't put a lot of
emphasis on the results of taus of less than 100 seconds or more than
6,000 or so..) I doubt I'm going to put much more time into this unit but it's
an interesting novelty in it's original state. The results of other
units may well differ (:
Regards
Mark Spencer
More information about the Time-nuts_lists.febo.com
mailing list