TELECOM Digest OnLine - Sorted: Re: What Exactly Did "Telstar" Do?

Re: What Exactly Did "Telstar" Do?

John Levine (johnl@iecc.com)
14 Dec 2004 07:46:50 -0000

> Was Telstar a production unit, expected to be a workaday medium, or
> just an experiment to see how satellite communications would work?

The latter. It was an AT&T ratepayer funded technology experiment.

They'd already had some success with the Echo I satellite which was
just a big mylar balloon. Telstar had an amplifier and ran uplink and
downlink on separate frequencies. I think it was the first satellite
to use solar cells and nicads.

Since it was in LEO, it wasn't very useful for telephony since it was
only visible both from Maine and from Britain or France for 20 minutes
at a time. They did experiments with voice and telex but what most
people remember is TV, since it was used to transmit the first live TV
across the Atlantic. It was only 20 minutes at a time, but since the
satellite's orbit was known, the 20 minutes could be slotted into TV
schedules. (Before that, transatlantic TV involved video tapes and
airplanes.) I get the impression that Telsat just did what it did,
and all of the operations were on the ground at the three ground
stations which had movable dishes to track Telsat as it passed
overhead.

Telstar only worked for about six months, apparently damaged by
radiation from above ground nuke tests. There was a second larger
Telstar II in 1963 in a higher but still not synchronous orbit, which
ended AT&T's satellite program.

By that time, Congress had chartered Comsat as the national satellite
operator. They launched Intelsat I aka Early Bird into synchronous orbit
in 1965, which started the modern communication satellite era,

John R. Levine, IECC, POB 727, Trumansburg NY 14886 +1 607 330 5711
johnl@iecc.com, Mayor, http://johnlevine.com,
Member, Provisional board, Coalition Against Unsolicited Commercial E-mail

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