Do you mean the reference oscillator for the 5372A? That was the
internal 10811 OCXO. Over a 1000 sec. run, drift wouldn't have any
affect on these numbers.
Ed
On 1/5/2012 12:54 PM, Azelio Boriani wrote:
Great, don't forget to specify what reference your measurements were made
from (or did I miss anything from your posts?).
We use the CW12 PPS for our GPSDOs.
On Thu, Jan 5, 2012 at 6:57 PM, Ed Palmer<ed_pal...@sasktel.net> wrote:
Okay, I've cooled off - a bit. The bottom line is that the 10 MHz output
of the CW12 isn't appropriate for what I wanted to do. Ah, the joys of
reading and understanding a spec sheet!
But let's not throw out the baby with the bathwater. Although the 10 MHz
output has it's issues for typical Time-Nut applications, the 1 PPS output
is great. Here are some measurements that I've made over the past few
years on a few GPS receivers and a couple of GPSDOs. I measure 1000
periods of the 1 PPS and look at the results. Every run gives somewhat
different results so I've shown some typical ranges. These measurements
were made with an HP 5372A. YMMV.
Device .............. Std Dev (ns).... Range (max-min)(ns) ... Device Type
Navsync CW12 ........ 4 - 5 .......... 20 - 25 ............... GPS Rcvr
Motorola UT+ ........ 40 - 55 ........ 95 - 110 .............. GPS Rcvr *
see below
Rockwell Jupiter .... 10 ............ 50 ................... GPS Rcvr **
Motorola M12M ....... 10 - 15 ........ 40 - 60 ............... GPS Rcvr
Trimble Thunderbolt . 0.4 - 0.5 ...... 2 - 4 ................. GPSDO
HP Z3801A ........... 0.3 ............ 2 ..................... GPSDO ***
* Most of my UT+ 'range' results were in this group, but there were a
few at 20 - 30.
** Only one result.
*** Only one result. I need to do more testing on the Z3801A
As you can see, the Navsync CW12 is by far the best of the GPS Receivers,
but nowhere near as good as the GPSDOs. However, imagine using the CW12 to
discipline a good OCXO to build your own GPSDO. Or using it to discipline
a PRS10 Rubidium or X72 Rubidium oscillator. You can't do it with the 10
MHz output, but the 1 PPS output is another story.
Ed
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