tim@seismo.UUCP (10/09/83)
I would guess that the propagation delay in a telephone connection would be negligible even if you are interested in using it to communicate with WWV. Keep in mind that when you call someone long distance, the delay you encounter before the person that you are talking to responds has to be twice the propagation delay. I have never noticed any delay that was of any consequence when I was talking long distance anywhere. Since that means that the delay is not noticeable, and since WWV is at most accurate to 1/10 second, you can expect to be perfectly accurate. I would like to hear from anybody with a contrary opinion. Tim@cit-vax
kwmc@hou5d.UUCP (10/11/83)
Of course the delay may be considerable if a satellite link is involved. The distance covered by the signal might be ~50,000 miles and the delay 50000/186000 = .26 seconds. What sort of accuracy do you require ? Ken Cochran hou5d!kwmc
dave@utcsrgv.UUCP (Dave Sherman) (10/14/83)
I call my grandparents in England from home occasionally, and the delays caused
by satellite routing make the calls almost useless. You can effectively
only have one-way communication at a time, and you have to wait for your
voice to get through before you get a reply. I don't know whether it's
just the combination of our exchange and routing in England through to
Coventry or what, but I know business callers wouldn't stand for it.
I've spoken to London from my office and the quality was fine.
Anyone know why the difference?
Dave Sherman
Toronto
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{cornell,decvax,ihnp4,linus,utzoo,uw-beaver}!utcsrgv!lsuc!davemel@houxm.UUCP (10/26/83)
Several articles point out the new $250 Heath WWV receiver/clock that can be used to sync a computer's clock to accurate time. Has anyone done this? How do you get the right date (the Heath only seems to capture minutes and seconds)? or hour? How can you sync up a large number of computers (20 or so)? How do you run the receiver/clock down in the basement of a 5 story building chock full of RF noise? Mel Haas , houxm!mel
karn@eagle.UUCP (Phil Karn) (10/28/83)
The Heath clock uses an encoded subcarrier on WWV intended for just such use. It is a 1-per-second burst of 100 hz tone, the duration of which encodes ones and zeroes. You can hear this code if you have a receiver with good bass response (or turn up the volume until the distortion makes the harmonics audible.) You will hear something like "tickthummmmm....tickthum....tickthummmmm...." etc. The subcarrier is continuous, even on the 29th and 59th seconds of each minute, but it is most easily heard during the silent intervals without an audio tone. This sequence gives the month, day, year and UT1 correction as well as the hour, minute and second. For details, get NBS Special Publication 432. This is what you get when you write to the address given during the half-hourly station ID. The only modulation on station WWVB on 60 Khz is this code, although it is in a slightly different format and the 1 hz sequence directly AMs the carrier. Phil