[time-nuts] Man with too many clocks.
tshoppa at gmail.com
Thu Nov 3 09:38:04 EDT 2016
Well, which 1PPS is the trigger? Is it from a "bare GPS"?
Even the GPS timing units will have the (un-sawtooth-corrected) PPS phase
make jumps by 20ns to 40ns peak-to-peak and that's a significant portion of
the 100ns period of your 10MHz.
Typical unsawtooth-corrected PPS phase jumps:
On Thu, Nov 3, 2016 at 9:22 AM, Peter Reilley <preilley_454 at comcast.net>
> I am using the 1 PPS for the trigger.
> On 11/3/2016 8:59 AM, Antonio A. S. Magalhaes wrote:
>> Tell us about your trigger: where is it?
>> A 2016-11-03 12:20, Peter Reilley escreveu:
>> I am the proverbial man with too many clocks and I don't know what time
>>> it is.
>>> To correct this situation I have decided to calibrate everything.
>>> I have a HP 5370B, a HP 6370A, and a HP 5328A all with the TCXO option.
>>> I also
>>> have some TCXO modules. I figured that I would calibrate them against
>>> my Trimble
>>> Resolution T GPS receiver.
>>> I put the 1 PPS signal in one channel of my scope and one of the 10 MHz
>>> signals in the other channel and look at the phase relationship. The
>>> TCXO's are
>>> already close enough that I should not be out by more than a fraction of
>>> a waveform.
>>> I understand that I have to deal with the 1 PPS without sawtooth
>>> I expected to see the 10 MHz signal bounce around but not move more than
>>> of a wave length. Instead I see the 10 MHz waveform appear steady for
>>> a few seconds
>>> then jump a significant portion of the wave. The jump is too much to
>>> be confident
>>> that I have not slipped one cycle.
>>> Can I do what I am trying to do or am I missing something?
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