[time-nuts] HP5370B Dead Time in TI Mode

Tom Van Baak tvb at LeapSecond.com
Sun Feb 23 20:29:52 UTC 2014


Tony,

I would suggest using the clean 10 Hz data and ignore the data with all those gaps. In a pinch you can make use of irregular data but it's usually such a pain it's not worth it.

To calculate the peak continuous sample rate you have to include all the measurement overhead; this would include Hyperterminal as well as the Prologix itself, not just the documented 5370B timing.

To get a realtime report of measurement rate use my command line comlog.exe tool (under www.leapsecond.com/tools/) instead of hyperterminal. If your com port# is 17, the command is:
    comlog /quick /ts:i 17,9600 -
This will give you microsecond timings for each read from the serial port.

/tvb


----- Original Message ----- 
From: "Tony Greene" <tonygreen924 at inbox.com>
To: <time-nuts at febo.com>
Sent: Sunday, February 23, 2014 10:25 AM
Subject: [time-nuts] HP5370B Dead Time in TI Mode


> Greetings,
> 
> 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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