> Hi Tom, > > a related very interesting experiment is to take the Horizontal Sync signal > from an old Tube-type TV, and feed it to a frequency counter with GPSDO time > base (preferrably). > > Got to be careful about the high voltages inside the TV though! > > BTW: it's not 15374KHz, there are some significant decimal digits (I don't > recall the formula to calculate the frequency exactly, but it was the total > number of frame lines multiplied by 59.94Hz or so). > > Then you can test how accurate the broadcasters' 27MHz reference clock is. > > One would be surprised how inaccurate(!) some broadcasters are, and how much > drift some Satellite providers have. > > A lot of the stability is dependent on the receiver of course, and how well > the receiver's VCXO locks to the Broadcaster. > > bye, > Said >
wrong All larger TV stations use Cs standards. What you don't know is that the FCC assigns SLIGHTLY different scan frequencies to each station on the same channel in a close area so when you are in a fringe area between two stations on the same channel, you will intentionally see both pictures superimposed with a rolling of the scan lines. Otherwise they would be locked and you would see only black and white bars. Satellite broadcasts are completely different and I do not know the FCC specification for those. _______________________________________________ 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.