| 摘要 |
PROBLEM TO BE SOLVED: To provide an AM data multiplex modulated wave signal demodulation circuit that demodulates a base band digital signal based on a multiplexed digital modulated wave signal from an AM data multiplex modulated wave signal. SOLUTION: In this AM data multiplex modulated wave signal demodulation circuit where a carrier with a frequency fc is amplitude-modulated with an analog signal at an AM modulator and a base band digital signal is demodulated from an AM data multiplex modulated wave signal on which a digital modulated wave signal is multiplexed at positions of frequencies (fc+fa), (fc-fa) in axis symmetry with respect to a carrier with a frequency fc on the frequency base, a carrier recovered from the AM data multiplex modulated wave signal by a carrier recovery device 1 is shifted byπ/2 at aπ/2 phase shift circuit 2, the AM data multiplex modulated wave signal and the recovered carrier shifted byπ/2 are multiplied by a multiplier 4 and the multiplied output is orthogonally detected at an orthogonal detector 7 by using two orthogonal carriers with a frequency fαand the high frequency component of the orthogonal detection output is eliminated by a low pass filter 8 and the result is outputted as a demodulation signal.
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