Satellite Model Anik A

Anik A was Canada's first domestic communications satellite (Anik is the Inuit's word for brother). It was launched from Cape Canaveral on a Thor Delta rocket on November 9th 1972. With the launch of Anik A, Canada became the first country in the world to have a domestic communications satellite system using a satellite in the geostationary orbit. Two more identical satellites were launched, Anik A2 in April 1973 followed by Anik A3 in May 1976. Why three satellites? To guarantee continuous service, a back-up spacecraft must be in orbit. To cover failures, particularly at launch, a third satellite should be available. It is cost effective to build three at the same time.

The Anik As were owned and operated by Telesat Canada. The original intention to have the satellites built in Canada was reversed in a controversial decision by Telesat to award a contract to the American firm, Hughes Aircraft Company, based on their lower bid. About 20% of the value of the contract went to Canadian firms though subcontracts with spar Aerospace Ltd. and to Northern Electric Company for the satellite structure and the communications electronics payload respectively. The Canadian firms were given contracts of similar value to provide systems for satellites that Hughes later built for the world market.

Photo provided by Telesat Canada

The Anik A design was based on the "bus" (frame) that Hughes had used for the Intelsat IV satellites. The cylindrical body of the satellite was spinning for stability. A "despun" section supported the antenna so that it could always be directed towards Canada. The antenna focussed the transmitted energy in a beam shaped to cover all of Canada. The area covered on the ground is called a footprint.

Communications satellites operate by receiving low level radio signals (e.g. TV or radio) from a ground transmitting station at one frequency, amplifying this signal, and changing its frequency for retransmission at another frequency. The transmission from earth is known as the "uplink" while the transmission from the satellite to earth is called the "downlink". Travelling Wave Tubes (TWT) onboard the satellite provide the power needed to amplify these signals for transmission down to earth. The frequency of the downlink is different from the frequency of the uplink to avoid interference. Several of these transponders can be operated simultaneously at different frequencies to provide service to individual customers. The process of separating the signals at different frequencies and recombining them is called "multiplexing".

Anik A operated in the 6/4 GHz bands (also referred to as C band), i.e.the uplink was at 6 GHz and the downlink was at 4 GHz. These frequencies were chosen for the first satellites because the technology was already in use for terrestrial microwave systems. But this created a problem in that satellite and microwave- signals could interfere with each other. Earth stations were located at sites far from urban areas to avoid interference. Anik A had 12 transponders each with 5 watts output power that could transmit 12 TV programs or the equivalent of 11,520 one-way telephone channels. The satellite was designed with a seven year lifetime.

A master station to control the satellite contained telemetry, tracking and command (TTAC) capability. It was located at Allen Park northwest of Toronto.

Communications services via the satellite were provided to customers by a network of more than 100 ground stations across the country. Eight television transmit stations were located near provincial capitals. Television receive stations provided good reception to remote communities with populations greater than 500(?). Earth stations to provide quality telephone service were installed in northern communities.

Reprinted courtesy of National Museum of Science & Technology