PHASE CONTROL METHOD FOR REDUCING AMPLITUDE PEAK OF FREQUENCY MULTIPLEXING SIGNAL, AND SIGNAL TRANSMITTER

摘要

PROBLEM TO BE SOLVED: To keep phase point arrangement for max. amplitude regardlessly of the variation in the frequency of a reference signal and to stabilize max. amplitude reduction by using a phase shifter capable of varying a phase by means of the voltage of the output of a phase comparator. SOLUTION: The output of a first frequency converter 3-(1) and the output of the second frequency converter 3-(2) are introduced to the first phase phase comparator 4-(1) and the output of the first comparator 4-(1) is fed-back to a first variable phase shifter 2-(1). Then, the phase of the output signal of the first variable phase shifter 2-(1) is controlled so as to permit phase difference between the two input signals of the first phase comparator 4-(1) to be π/(N-1). Thus, the phase difference between the difference frequency signals of an adjacent VSB and AM modulator is arranged in accordance with the declination of a phase point which divides circumference into N-1 on a basis of the phases of the difference frequency signals of the first VSB and AM modulator 1-(1) and the second VSB and AM modulator 1-(2).