--- Jack Smith <[EMAIL PROTECTED]> wrote: > That was true at one time, but is it still the case? I recall reading > that with the switch to digital video distribution color burst is > locally generated and hence not tied to the NBS standards. > > > Jack K8ZOA
NBS Special Publication 432 used to describe this method back in the late 70s, early 80s, but as was pointed out, it is no longer valid. Personally, I have a homebrew 10 digit frequency counter (99% complete) combined with a homebrew frequency reference locked to WWVB (60 kHz) (also 99% complete) which is used as a timebase for the counter. I can measure WWV and CHU's HF signals, and resolve the Doppler shift that occurs as the signals from these stations propagate via the ionosphere. :-) I have discovered that AM radio stations that carry IBOC digital broadcasts have generally VERY accurate and stable carrier oscillators. Some are based on Rubidium oscillators tied to GPS clocks! If you use this method for testing / calibration, just make sure you're receiving groundwave (not skywave) because of the Doppler effects earlier described. 73, de John, KD2BD Visit John on the Web at: http://kd2bd.ham.org/ . . . . ____________________________________________________________________________________ Looking for earth-friendly autos? Browse Top Cars by "Green Rating" at Yahoo! Autos' Green Center. http://autos.yahoo.com/green_center/ _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com