Xref: utzoo sci.electronics:3056 sci.astro:2196 comp.dcom.modems:1941 comp.misc:2538 rec.ham-radio:5018 Path: utzoo!utgpu!water!watmath!clyde!bellcore!rutgers!cmcl2!phri!roy From: roy@phri.UUCP (Roy Smith) 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: <3335@phri.UUCP> Date: 7 Jun 88 00:37:44 GMT References: <455@trane.UUCP> <4691@watcgl.waterloo.edu> <585@otto.COM> Reply-To: roy@phri.UUCP (Roy Smith) Organization: Public Health Research Inst. (NY, NY) Lines: 19 glenn@otto.UUCP (Glenn Scott) writes: > In addition, the "speed of light delay" via satellite shouldn't be much > different than the speed of light delay over a copper wire... If I call Colorado from New York and get a land line, I'm going over maybe 3-4000 miles of path (doesn't make much difference if it's copper wire, microwave, or fiber; in reality it's probably a combination of all three). For a 3000 mile path at 300,000 miles/second, that's a 10 msec delay. The kicker is that commsats are in geosynchronous orbit. If I remember correctly that means an altitude of 23,000 miles, making the path length twice that (uplink + downlink) or 46,000 miles. That's about 150 msec. -- Roy Smith, System Administrator Public Health Research Institute 455 First Avenue, New York, NY 10016 {allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net