In this case, cable quality is critical and controlling cable characteristics (as a function of temperature, humidity, etc.) is also critical. Jeff
Jeffrey K. Okamitsu, PhD, MBA +1-609-638-5402 --- On Fri, 10/3/08, Bruce Griffiths <[EMAIL PROTECTED]> wrote: From: Bruce Griffiths <[EMAIL PROTECTED]> Subject: Re: [time-nuts] AC Connector On HP 5061B To: "Tom Van Baak" <[EMAIL PROTECTED]>, "Discussion of precise time and frequency measurement" <[email protected]> Date: Friday, October 3, 2008, 4:58 PM Tom Van Baak wrote: >> On the DA you will want to ensure all your output cables are of >> identical length as this will ensure that all signals are in phase at >> the timebase input(s). It's a small thing really a fraction of a >> picosecond but it's there and easily compensated for. >> > > When does the phase of the timebase input mean anything? > Most test equipment is happy to have a stable external frequency > input; the phase is immaterial, no? Can someone give me an > example when relative phase among various random pieces of > test equipment is important? > > /tvb > > Tom Another example of a case where the electrical length of a cable can be important is in precision frequency distribution systems. Trimming the cable to the right length (one way propagation delay equal to an odd multiple of half the signal period) for the frequency in use minimises the effect of load and source mismatch. Bruce _______________________________________________ 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.
