Fergie's Tech Blog

23 July 1962: Telstar Relays First Live Trans-Atlantic TV Signal

Telstar was the first active communications satellite, the first satellite designed to transmit telephone and high-speed data communications, as well as the first privately owned satellite. Its name is used to this day for a number of television broadcasting satellites.

Belonging to AT&T, the original Telstar was part of a multi-national agreement between AT&T, Bell Telephone Laboratories, NASA, the British General Post Office, and the French National PTT (Post & Telecom Office) to develop satellite communication. Bell also built the Andover Earth Station in Andover, Maine, and held a contract with NASA, reimbursing the agency three million dollars for each launch, independent of success.

The satellite was built by a team at Bell Telephone Laboratories. It was roughly spherical, was 34.5 inches (880 mm) long, and weighed 170 pounds (77 kg). Its dimensions were limited by what would fit in one of NASA's Delta rockets. Telstar was spin-stabilized, so its outer surface was covered by solar cells in order to always receive some power. The power produced was relatively tiny.

Telstar was equipped with a helical antenna which received microwave signals from a ground station, then amplified and rebroadcast the signal. The broadcasts were made from a series of somewhat directional feed horns distributed around the satellite's "equator". The electronics switched which antenna was active as the satellite rotated.

When received back on the ground again, the signal was only a nanowatt or so in strength and a maser amplifier was therefore used to increase signal detection ability. Two primary ground stations were built, the Andover Earth Station in the US, and Pleumeur-Bodou in France. The orbital path was chosen to be visible from both stations.

posted by Fergie @ 7/23/2006 12:01:00 AM