Hi Azelio, On 07/06/2013 05:05 PM, Azelio Boriani wrote:
Not only: consider that most time interval counters have a minimum measurable interval (Racal 2351 is 2ns) and slowly crossing PPSes can be a problem to measure when they are about to cross. In my opinion it is always better to displace the PPSes, easily done when using GPSDOs and by using stable delay lines in other cases. The Racal 2351 has +/-TI measurement function.
Any such offsets can be troublesome with free-wheeling oscillators where you measure the PPS signal over a long time.
If you can, it is better to use a higher rate, trigger on PPS (either as START or STOP) or ARM on PPS and then have start and stop operate on the higher frequencies.
Naturally, the PPS can be replaced with an equalent signal at a different rate. The problems discusses is really with rate, so what happens at 1 Hz occuurs at 10 Hz or 100 mHz just as well.
There is counters able to handle these problems much neater. The HP5371A/HP5372A/HP5373A actually time-stamps the events. What few realize is that you can use the fast port for long or even continuous measurements. Some of the Pendulum counters, CNT-80/81 and CNT-90/90XL/91, I believe can do continuous measurements properly, but I haven't tried it properly.
Cheers, Magnus _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
