[time-nuts] Question about an HP5370B TIC
Bob Smither
smither at c-c-i.com
Fri Sep 30 04:38:20 UTC 2011
Dear Group,
I recently obtained a used HP5370B. Running through the operator checks
in the Operating and Service Manual (figure 3-4) it seems to be
operating perfectly.
I am trying to use it to compare two 1pps signals - one from a GPS
receiver and one derived from a fairly decent 10MHz OCXO. The GPS
signal is applied to the start channel and the derived to the stop channel.
As long at there is always a positive or always a negative time
difference between the two 1 pps signals the result makes perfect sense.
There appears to be about a 2 to 3 usec jitter in the 1pps from the
GPS (this is expected given the design of the receiver).
If I put the 5370B in the +/-TI mode I expected to see both + and -
small time differences when the two signals are closely aligned - and
mainly I do. Typically the difference is + or - a usec or less.
Occasionally however the 5370B displays very near to a +1 or -1 second
(999.999 xxx ms or -1.000 000 xxx s for example) reading. Needless to
say this plays havoc with trying to measure a mean value of the
alignment. The 5370B is clearly measuring the "outside" between the
pulse pair when I want it measure the "inside" (or short time interval)
between the pulse pair.
Is this normal behavior? Is there a setup that I am missing to make it
do what I want?
Thanks for any insight you might give me!
Best regards,
--
Bob Smither, Ph.D. Smither at c-c-i.com
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