From: Peter Schmelcher <[EMAIL PROTECTED]> Subject: Re: [time-nuts] GPS Phase locked Local Oscillator experiment Date: Thu, 08 Mar 2007 10:55:29 -0800 Message-ID: <[EMAIL PROTECTED]>
> > >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+. If you have a smaller offset, you get a better dither-curve (a sawtooth) rather than a square-wave. Your 3325A has _no_ problem at all doing that. :) Also, I would run the 3325A from one of your Rubidiums. > >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. Indeed. > >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. It should be a fairly short script to do it. :) Personally I fancy real programs (in C). Cheers, Magnus _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
