Demodulator control system and a receiver capable of quickly acquiring a desired carrier wave

A demodulator control system for controlling operation of demodulating means which is for demodulating each of a plurality of modulated signals in accordance with a demodulating frequency into a demodulated signal, said modulated signals being transmitted by the use of a frequency division multiple access system, said demodulator control system including a local oscillator for carrying out a sweeping operation to successively produce, as said demodulating frequency, a plurality of local oscillation frequencies one at a time and sweeping control means for controlling said sweeping operation with reference to said demodulated signal, said demodulated signal carrying a unique word and an identification number, said sweeping control means comprising:

• a number comparing circuit connected to said demodulating means for comparing said identification number with a desired one of predetermined numbers in response to said demodulated signal to produce a number coincidence signal when said identification number coincides with said desired one;
• a unique word detecting circuit connected to said demodulating means for detecting said unique word in response to said demodulated signal to produce a unique word detection signal;
• and
• an oscillator control circuit connected to said local oscillator, said number comparing circuit, and said unique word detecting circuit for controlling said sweeping operation in response to presence and absence of each of said number coincidence signal and said unique word detection signal.