| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that a ripple corresponding to a subcarrier remains when envelope detection is applied to a determining signal indicating the sound type from a control signal S of television sound multiplex broadcast. SOLUTION: A prestage 4 and a poststage 6 can each apply envelope detection to a amplitude-modulated subcarrier. When detecting the control signal S, the prestage 4 generates the ripple when the voltage of its output signal S' decreases while it may generate the ripple when the voltage increases. The poststage 6 has a configuration inverse from that of the prestage 4 in voltage relation, and can suppress the ripple when the voltage increases. By applying the output signal S' of the prestage 4 to the poststage 6, the ripple of the signal S' is eliminated. COPYRIGHT: (C)2006,JPO&NCIPI
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