| 摘要 |
PURPOSE:To prevent the impression of malfuction of stereo display unit, by making independent the stereo display drive circuit and driving it with the output of the pilot signal control circuit, in the FM stereo receiver in cars. CONSTITUTION:When the FM stereo composite STC signal is fed to the noise suppression circuit 11, the circuit 11 interrupts the STC signal during the period in response to the width of noise generation and outputs it to the demodulation circuit 2. The demodulator 21 in the circuit 2 produces the left and right stereo signal separated, and in the pilot PL signal generating circuit 22, the shaped PL signal in synchronizing with the PL signal frequency is inputed to the PL signal control circuit 13. Further, the DC voltage generating circuit 23 in the circuit 2 produces the DC voltage in response to the amplitude of the PL signal and inputs it to the circuit 13. The circuit 13 drives the stereo signal in the circuit 23 and displays the display unit 3. Since the circuit 14 is separated from the driving of the circuit 23, the malfunction of display unit due to a weak current is prevented to reject the impression of malfunction. |
