[time-nuts] Measuring 1 PPS with an HP 5335A

Bob Camp lists at rtty.us
Sun Feb 16 17:07:17 EST 2014


Hi

If you have a 50/50 duty cycle 1 pps, it’s going to work with a lot of settings. With a narrow (say 10us wide) pulse, most of the counters have auto trigger issues. If it’s already known to be reading nutty, trigger is a good place to start looking.

Bob

On Feb 16, 2014, at 4:29 PM, Paul <tic-toc at bodosom.net> wrote:

> On Sun, Feb 16, 2014 at 2:33 PM, Bob Camp <lists at rtty.us> wrote:
> 
>> On all these counters, you need to switch to DC input for 1 pps signals.
>> You also need to manualy set the trigger level to something like +1.5V.
> 
> 
> I can't believe I'm disagreeing with Bob Camp but this is not my
> experience.  99.9% of the time preset trigger works fine and I think you
> should start with that.  AC coupling almost always works and is sometimes
> required (with the Rb I think).
> 
> I have a 5335A (w/ opt 010+040) and have measured 1PPS on my PRS-10, Fury,
> Firefly and random GPS parts.  If the trigger light is not flashing at 1 Hz
> the only thing I've ever had to do is toggle AC coupling or enable 1PPS
> output on the device (or plug it in).  Sometimes increasing the gate time
> tidies up the display.
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