John Miles wrote:
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?From what I've seen it's best to stick with +TI mode for measurements likethis. You don't want the counter making decisions about which half of the interval is "short" and which half is "long" -- it just doesn't add anyvalue to the measurement.
Thanks John. I moved the OCXO edge about 100 usec after the GPS 1PPS and now I can use the +T1 mode. It just seemed more "natural" to try to line up the edges.
From your response I am going to assume that the behavior I observed is in fact normal and my 5370B is OK?
Best regards, -- ======================================================================= Bob Smither, PhD [email protected] A flag you can burn ... is the only kind worth dying for. =======================================================================
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