[time-nuts] HP5370B Dead Time in TI Mode

Tony Greene tonygreen924 at inbox.com
Sun Feb 23 13:25:44 EST 2014


I have run some time interval test and it did not quite calculate correctly.  I used a TADD2 that is configured for 2 outputs at 100 Hz, 2 outputs at 10 Hz, and two outputs at 1 PPS.  The HP5370B clock output was used as the input for the TADD2.  The output of the TADD2 was feed to both time interval inputs using a tee.  I am using a ProLogix GPIB/USB adapter and hyperterminal in windows to capture the data.  The object of the test was to make a baseline noise floor measurement.

The 5370B manual shows there must be a minimum of 330 microseconds between measurements.  If the unit is put in the time interval binary mode via the GPIB, the unit can output up to a 6 Khz rate on measurements.  The 5370B manual does not state what the instrument can output on the GPIB, in normal use (meaning, not in the time interval binary mode - just plain talk mode).

I made some measurements using 100 hz to both inputs and in one hour, the data file shows only 51437 samples.  This equates to 14.288 samples per second.

I made some measurements using 10 Hz to both inputs and in one hour, the data file shows 35988 samples.  This basically works out to 10 samples per second, as expected.

Knowing the results at 100 hertz, how can one tell a program such as Stable32 or Plotter about the dead time between measurements ?  Or would it be best to keep the inputs at a maximum rate of 10 PPS, and say thats the limits in the normal TI mode ?

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