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[time-freq] RefLock II behavior

Owen, Michael Michael.Owen at Sensis.com
Wed Jun 21 17:58:40 UTC 2006


Hi, Luis -

The OCXO's tuning range is specified as "+/- 4e-6" which I interpreted
as +/-4 Hz.  However, I can pull it +/- 400 Hz so that interpretation
must be wrong.

I'm not sure what the proper level of the 1PPS should be, but mine is
5.5 volts p-p which seems like enough.

I looked at the 1PPS with an oscilloscope and it is indeed rather furry.
Perhaps 0.1V of high-freq noise on it.  I'm not sure what would be the
best way to clean it up.  

I have tried the 1PPS polarity both ways... Behavior seem the same.

I reduced the spikes considerably by changing R23 back to 10K.  There is
still +/- 0.5 Hz of wander, constantly.

MRO

------
Michael R. Owen, Ph.D.
Senior System Engineer
Sensis Corporation
(315) 634-3066 


|Michael,
|
|With +-4Hz range, the +/-0.5Hz  it is clearly not a dac 
|dithering issue. It is a gps-1pps issue for sure.
|
|Luis Cupido
|CT1DMK.
|
|P.S. Basic question, is the input level ok ?
|is the CPLD receiving a clean sq wave ?
|Are you sure of the 1pps polarity ?
|
|




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