[time-nuts] GPSDO using 100Hz

Mike Monett XDE-L2G3 at myamail.com
Tue Nov 25 00:20:07 UTC 2008


  > Mike

  > Note: I  gave  you a simple example of why it is  not  possible to
  > just buffer the High Freq osc . The actual working get a  bit more
  > complicated.

  > In short when it is time to give out the next pulse whether  it is
  > 1 Hz  or  100  Hz It sends it outs as  close  as  possible  to the
  > correct time,  using some internal clock. What I have seen  on the
  > Oncore is  that this causes a peak of +- 50ns of jitter.  It works
  > the same  with the 100Hz or the 1 Hz, both have the  same  peak to
  > peak rising edge jitter, which is different for each pulse sent.

  > The 1Hz  timing error message it sends out has little  to  do with
  > the 100 Hz timing.

  > And is not relevant when using the 100Hz except for a few advanced
  > alising issues.

  > I hope that answers your questions. Can I ask why the interest?

  > Warren

  Ok, it seems they are calculating the best time for each 100Hz pulse
  individually. That makes life a bit easier for a PLL.

  My interest is I have a totally new way of locking to the 1PPS pulse
  that should  improve the performance dramatically.  The  question is
  would it also work with a 100Hz signal.

  The answer is yes. It would also work with a 10KHz signal,  but this
  would require  a  bit  more horsepower. I was  planning  on  using a
  simple inexpensive microprocessor for everything but I don't know if
  it would be fast enough to do 10KHz.

  But there's not many of those around anymore, are there?

  Best Regards,

  Mike Monett




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