Hi I agree with you on the spec sheet and the fact that the cpu *should* extend the data. My observation was that it didn't do it if the input frequency was high enough. I tried it on a couple dozen counters built over a period of several years.
Bob -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Magnus Danielson Sent: Wednesday, January 06, 2010 12:10 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Newbie questions Hi! Bob Camp wrote: > Hi > > Ahhh, that jogs a few of the tired old brain cells.... > > You can run the gate off of the GPIB input to get all kinds of silly long > gates. Then you start to get into the cpu overflow issues. Since it's a MSB > overflow you can usually clean it up in software *if* you know it's > happening. Notice that it is specified to support gate-times up to 10 Ms (10^7 s). I would suspect that both the event and time counters is CPU extended. Maybe I should pull the PROM and do a readout. > Since the GPIB is simply telling the counter "start about now" and "finish > it up now" the accuracy of the GPIB timing does not get into the result. The > counter still uses it's time base as the standard of comparison. Well, it will cause a variation in gate-time (about 2 ms can be assumed, since that is what programmed gate using GA allows) , but since this is used for longer gate times it is not significant. If better precission is needed, the external arm input shall be used. Cheers, Magnus _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
