I found the parameters for the X72's 1PPS input. The range of Tau is 5 -
10,000 seconds, or about 2 hrs, 45 min. at the longest setting. It
defaults to 400 seconds. However, mine doesn't have the firmware to enable
the 1PPS input, so it really doesn't matter.
Out of curiosity, does anyone know of any Rb units that can be programmed to
a 24 hr (or longer) Tau, either by EFC or 1PPS input?
Dave M
Bob Camp wrote:
Hi
It is not what is done in the Efratom Rb’s. Their pps input is set up
to get things on frequency / on time quickly. The assumption is that
you plug it into a pps to get it “right” and then take off on your
mission. That takes them into the short (for a Rb) time constant
region.
Bob
On Aug 24, 2014, at 5:56 PM, Brooke Clarke <[email protected]> wrote:
Hi Bob:
I think that's what's done in the SRS PRS10
http://www.prc68.com/I/PRS10.shtml
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
http://www.prc68.com/I/DietNutrition.html
Bob Camp wrote:
Hi
If you lock an Rb to GPS, you need / want / should do it with a
*very* long time constant. Numbers in the one day to several days
range are commonly seen. If you lock it up with a tighter (shorter
time constant) loop, it will just wander around as it follows the
GPS input. That’s what would happen if you hook your Rb to your
Trimble and turn on the disciplining on the Rb. It will
significantly degrade the stability of the Rb.
If you have a temperature stable environment (or create one) you
can get some very good results with an (good) Rb locked to a (good)
GPS via a proper long time constant setup. It’s not easy, but it
can be done.
Bob
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