AM DATA MULTIPLEX MODULATOR

摘要

PROBLEM TO BE SOLVED: To provide the AM data multiplex modulator in which a digital signal is multiplexed onto an AM modulation signal so as not to give effect onto an AM synchronization detection output in the case of conducting AM synchronization detection. SOLUTION: An AM modulator 1 applies AM modulation to a carrier whose frequency is fc by a signal wave, and an orthogonal modulator 3 applies orthogonal modulation to a carrier with a frequency of (fc +f ) with a QPSK base band digital signal outputted from a QPSK base band digital signal generator 2. On the other hand, a sign of a component in phase to a reference carrier phase of a vector shift corresponding to a dibit formed by a QPSK base band digital signal outputted from the QPSK base band digital signal generator 2 is inverted by a sign inverter 4, the result is given to a complex conjugation device 5, and an orthogonal modulator 6 applies orthogonal modulation to a carrier whose frequency is (fc -f ) with an output signal from the complex conjugation device 5. An adder 7 adds the output signals from the orthogonal modulators 3, 6 and an adder 8 adds the sum from the adder 7 and the output signal from the AM modulator 1 to obtain an AM data multiplex modulation output.