Communications satellite. Illustration showing a communications satellite stationed above Europe. A signal is being beamed up to the satellite from London (red line) and beamed down to Rome (blue line). Communications satellites act as relay vehicles for radio signals. Most communication satellites are now placed in geosynchronous orbit 35,700 kilometres above the equator. In this orbit, the orbital period is the same as the Earth's rotation period, so the satellite appears to 'hover' above the same point at all times. Communication satellites are used to relay telephone and fax messages, computer data and to broadcast television signals.