Article View: sci.electronics
Article #19202Re: N.B.S. Time Service
From: Roy Smith
Date: Tue, 07 Jun 1988 00:37
Date: Tue, 07 Jun 1988 00:37
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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
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Path: arc1-ca.pugleaf.net!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