[time-nuts] GPS Phase locked Local Oscillator experiment

[Peter Schmelcher]

>Wonder how the Z3816A would like a modified VP inside... Hmmm... a closed
>loop system, what are really the timeconstants relevant, to make sure it
>is stable?

That is where I am going. The UT+ oncore inside the Z3816A is a simple 
crystal and easy to feed with the 3325A. I currently have an ongoing oven 
turning point experiment with the MTI oscillator or I would have done it 
already. The frequency of the local oscillator will need to be different by 
0.5 Hz I think. The pps pulse needs to jump back and forth by 1 clock cycle 
for the pps pulse to have any feedback information in it when the local 
oscillator is phase locked unless the Z3816A reads the sawtooth residual 
from the internal UT+.

>The big difference is that Peter used another GPS clock as reference. By that
>he is actually doing a delta measurement between the receivers. Hooking the
>3325 up to a Cesium would be a much more interesting measurement.

I have measured the stability of the Z3616A 10MHz output indirectly by 
measuring a good ovenized crystal oscillator in the past it is less than 
50uHz rms with 10 samples of 1.8 seconds. For comparison my two rubidium 
oscillators are about 200 to 350 uHz rms. The HP engineers did a good job.

>You would like to query the receiver in a different maner, so that would
>require a modified firmware.

My data logging is not what it should be. I do not know a simple way to log 
the sawtooth data to a file so I did a screen capture.

Peter