[time-nuts] Sending me Lady Heather screen-captures....

Mark Sims holrum at hotmail.com
Tue Dec 29 06:44:10 UTC 2009


Those spikes/decays in the temperature plot are due to false readings the Tbolt firmware gets from the temperature sensor chip.  They are an artifact of how the temperature sensor works in its "high resolution" mode.  They are actually single sample spikes of 1C (I think) in the output of the sensor chip.  The reported amplitude/decay is due to the filtering the Tbolt firmware does on the temperature readings.

Also,  remember that the ADEV values calculated by Lady Heather are from its internal measurements of the oscillator and PPS signal against the rather-noisy-in-the-short-term GPS signal.   They tend to depart from the true ADEV values measured against a real external reference particularly at shorter values of tau (like <100 secs).

Turn on  the satellite count display (G C from the keyboard in ver 3.0).  The Tbolt reacts rather poorly to changes in the group of satellites that it is tracking.   When the tracked satellite constellation changes,  you can get big jumps in the osc/pps/dac signals.  

To minimize constellation changes,  set the signal level mask to a low value (like AMU=1.0) and the satellite elevation mask to a high value (like 25 degrees). 		 	   		  
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