Communications satellite of a GEO satellite. Like LEOs, these satellites don’t maintain a stationary distance from the earth. This is in contrast to the geostationary orbit, where satellites are always approximately from the earth. Typically the orbit of a medium earth orbit satellite is about above earth. In various patterns, these satellites make the trip around earth in anywhere from 2 to 8 hours. In 1962, the first communications satellite, Telstar, was launched. It was a medium earth orbit satellite designed to help facilitate high-speed telephone signals. Although it was the first practical way to transmit signals over the horizon, its major
Satellite television which was distributed via satellite was usually sent scrambled or unscrambled in NTSC, PAL, or SECAM television broadcast standards. The analog signal is frequency modulated and is converted from an FM signal to what is referred to as baseband. This baseband comprises the video signal and the audio subcarrier(s). The audio subcarrier is further demodulated to provide a raw audio signal. Later signals were digitized television signal or multiplex of signals, typically QPSK. In general, digital television, including that transmitted via satellites, is based on open standards such as MPEG and DVB-S/DVB-S2 or ISDB-S. The conditional access encryption/scrambling methods include