| 摘要 |
An FM stereo signal demodulating apparatus includes a bandpass filter 1 for extracting a 19 Hz signal from an FM detected signal; a first phase shifter 21 for phase-shifting the 19 Hz signal by 90 degree; a first XOR 22 for taking an exclusive OR between an output from the first phase-shifter 21 and the 19 KHz signal; a second phase shifter 23 for phase-shifting an output signal from said XOR 21; a second XOR 24 for taking an exclusive OR between an output from the first XOR 22 and an output from the second phase shifter; an inverter 25 for inverting an output from said XOR 24; a third phase-shifter for phase-shifting an output signal from said inverter 25; a third XOR for taking an exclusive OR between an output from said third phase-shifter 26 and an output from said first XOR 22; a first multiplier 3 for multiplying an output from said first XOR 22 and said FM detected signal; a second multiplier 4 for multiplying an output from said third XOR 27 and said FM detected signal; a third multiplier 5 for multiplying an output from said second multiplier 4 by {square root over (2-1; a first adder 6 for adding an output from said first multiplier 3 and an output from said third multiplier 5; a second adder for adding said FM detected signal and an output from said first adder 6; and a subtracter 8 for subtracting an output from said first adder 6 from said FM detected signal. In this configuration, the FM stereo demodulating apparatus can operate as a low speed.
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