Like I mentioned in a precedent message (answering Magnus) I'm seeing some temp effects on my GPS module, see this message: http://www.febo.com/pipermail/time-nuts/2012-December/073310.html
In this graph there are the FE5680 voltages and temperatures, and the temperature sensed on the PCB near the GPS: http://www.flickr.com/photos/14336723@N08/8318815981/ At time 20000s I heated the GPS receiver directly with hot air gun and the drift started to change rapidly. At 25000 I heated the FE5680#2 I was using as reference, but no visible effects, (apart the slight variation in it's voltage :) At 30000 33000 35000 seconds I heated the GPS with a resistor placed near the PCB, this generated more gradual temperature variation on the GPS. Here can be seen the results of the heating on the drift, (logging GPS PPS against Rb): http://www.flickr.com/photos/14336723@N08/8318816213/ the hotair generated so much variation, that the script was unable to unscrable the data. The resistor heater generated slower temperature variation on the GPS, it's visible a glitch everytime there was a temperature variation, and the drift magnitude seem to follow the variation of the temperature in time (dT/dt). I will try to reduce temperature sensivity incrementing the thermal capacitance and isolating the GPS from the ambient. Is this normal or it's a defect ("feature") of my unit? I'm also curious about what internal structure can generate this wander in PPS. Like I said before it's like if the PPS pulse (for intervals of few 100's of nS) depends on something that is very temperature dependent. Thanks, Fabio. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
