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Time Delay Measurement

Question asked by GreenEngineer on Mar 10, 2009
Latest reply on Apr 6, 2009 by Dr_joel
Good Afternoon,

I am using an HP8753 w/ 6GHz option to measure the delay in a set of cables.  The cable has an straight N-Type Male connector on one end and a right-angle N-Type Male on the other.  I used full 2-Port calibration with adapter removal to calibrate my test setup.  The sweep time is set to 5 sec. with the span set to the Full 6GHz with smoothing at 20% (averaging off).  These are the results of my test (at 978MHz).

S21 delay 3.0423 ns
S12 delay 3.0838 ns

With my cable setup, this equates to a difference between forward and reverse delay of about 1/2" of delay (if converted to physical length).

I flipped the cable around and the results...

S21 delay 3.0426 ns
S12 delay 3.0842 ns

I am wondering what this difference between forward and reverse delay could be attributed to.  I feel like it may be something in my calibration, although I followed the Adapter Removal method to the letter in the HP8753E manual.  Perhaps it has something to do with the male and female cal standards being different?  If anyone has any ideas on this discrepancy please share.