Xref: utzoo sci.electronics:3055 sci.astro:2195 comp.dcom.modems:1940 comp.misc:2537 rec.ham-radio:5014 Path: utzoo!utgpu!water!watmath!watcgl!awpaeth From: awpaeth@watcgl.waterloo.edu (Alan Wm Paeth) Newsgroups: sci.electronics,sci.astro,comp.dcom.modems,comp.misc,rec.ham-radio Subject: Re: N.B.S. Time Service Keywords: Time Ticks Message-ID: <4735@watcgl.waterloo.edu> Date: 7 Jun 88 14:49:51 GMT References: <455@trane.UUCP> <4691@watcgl.waterloo.edu> <585@otto.COM> Reply-To: awpaeth@watcgl.waterloo.edu (Alan Wm Paeth) Organization: U. of Waterloo, Ontario Lines: 25 In article <585@otto.COM> glenn@otto.UUCP (Glenn Scott) writes: >In article <4691@watcgl.waterloo.edu>, awpaeth@watcgl.waterloo.edu (Alan Wm Paeth) writes: > >>As I recall the current telephone number arrangement is truly by >> "land-line" -- the NBS has arranged with Bell that the signals not be >> routed via satellite, as the speed of light path delay becomes a >> significant fraction of a second. > > If I originate the call, my local telephone provider doesn't necessarily >know that I'm calling the NBS Time Service, and it would route my call via >the most viable way. That's not likely to be via "land-line" from Nevada >to Colorado. In addition, the "speed of light delay" via satellite shouldn't > be much different than the speed of light delay over a copper wire... I believe the arrangement involves the use of (900) prefix numbers, but your arguments are compelling. I saw the reference in "Sky and Telescope" last year. The "speed of light delay" is indeed significant for a return bounce to a geosynchronous satellite at 40,000km. Talking long distance to Europe (from North America) can be very trying (many starts, stops and interruptions), because the delay is long enough to be interpreted as an intentional "pause", at which point both parties resume speaking, only to stop immediately when they hear the (delayed) voice of the other party. /Alan Paeth