In a receiver set, a shared receiver receives a signal formed according to one of various modulation or communication systems to output a received signal. A signal intensity detector detects the electric power value, or absolute value of the amplitude, of the received signal to output a detected signal. A determiner compares the magnitude of the detected signal with threshold voltages, and generates control signals to output them to switches. The switches are operated in response to the respective control signals fed to the switches so that the received signal is selectively fed to demodulators. The demodulators demodulate the received signal according to a receiving system corresponding to the modulation or transmission systems to output demodulated signals.