[time-nuts] +/- TI button on 5370B

[Bob Camp]

Hi

Another simple "solution" - 

If you are using a GPSDO as a PPS source, use the cable delay to offset the pps you are using as a reference  by a microsecond. That's worked on every GPSDO I've tried it on. 

No it really doesn't solve the problem, it just covers it up. Post processing the data is the only real way to straighten things out in the general case. 

Bob

On Jun 12, 2013, at 2:48 AM, Said Jackson <saidjack at aol.com> wrote:

> Jim,
> 
> Really annoying feature of HP counters.
> 
> If you slowly drift from a positive period to a negative one, it will indicate negative numbers for a while.
> 
> Then almost sudden it will do the jump to 0.99999xxxx seconds.
> 
> I found that adding a phase delay (long cable) helps keep the numbers positive.
> 
> Or trigger one on the rising, and one on the falling edge to add 50ns delay ( for signals with good 50% duty cycle).
> 
> Bye,
> Said
> 
> On Jun 11, 2013, at 21:13, Jim Palfreyman <jim77742 at gmail.com> wrote:
> 
>> Folks,
>> 
>> I'm struggling to understand this button and how it reports intervals. It's
>> supposed to show negative when the Stop is before the Start.
>> 
>> When I connect up two clocks sending out 1PPS and say the one connected to
>> Stop is ahead then sometimes I'd get -123.45 ns (say) and sometimes it
>> flips to 999.999... ms. It can't seem to make up its mind which to use.
>> 
>> Why is this inconsistent?
>> 
>> If I flip it to + TI and make sure the leading clock is on Start - all
>> works well.
>> 
>> Thoughts?
>> 
>> Jim Palfreyman
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