Abstract: In an earth-based receiving station for receiving radio signals transmitted from a satellite relay station, a common first frequency converter and at least two receivers are provided. One of the receivers is used as a control receiver to receive a CSC carrier frequency transmitted from the satellite, to generate a first local oscillator frequency phase-locked to the CSC carrier frequency, and to supply the first local oscillator frequency to the common first frequency converter. Other receivers are used as channel receivers for receiving channel frequencies. In case when the control receiver is in trouble, any other receiver can be used as a control receiver.