[time-nuts] Coarse adjustment of PRS-10 with 5335A

[Bob Camp]

Hi

Ok, you are fine with the 10 MHz reading on the 5335 to get things "sort of close". Once you get past about 1.0x10^-10 you may want to switch over to a pps based approach. More or less:

Fire up 5335 with pps from gps / gpsdo and from the PRS-10. (I'm assuming it's a GPSDO)
Watch the reading for a few seconds, record the average and the time. 
Go have lunch / nap / beer / what ever.
Check the time and the reading. 
Do the math
Bump the PRS-10
Step / repeat at the couple hour time interval for a day or so.
Drop back to a couple days, check and (maybe) adjust.
Drop back to once a week, check and (maybe) adjust.

Note that the 5335 only has to be on while you are actually observing the pps. No need for the heat / wear and tear the rest of the time. Your pps needs to run all the time, but that's only a problem if there is a power outage.

The advantage of doing it this way is you get both high resolution and averaging at the same time. Since there's pretty much nothing to set up (no computers / no GPIB) it's reasonably foolproof. Assuming that the 5335 is doing it's thing and that the GPSDO is good to roughly the same level:

3 hours is 10800 seconds
your reading is good to 3 ns (2 on the GPSDO and 1 on the counter)
you  get +/- 3.0x10^-9 at 1 second
you get about +/- 3x10^-13 at 3 hours.

Since the ADEV of the Rb is much better at the longer Tau's, the data you are using is probably a better bet than anything you can do in less time.  

Bob

On Sep 2, 2013, at 9:20 AM, Paul <tic-toc at bodosom.net> wrote:

>> If you are trying to measure frequency with the 5335 rather than pps signals
> 
> Ah, I was unclear.  I'm adjusting the 10MHz output.  It was pretty far
> out when I got it.
> 
> --
> Paul
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