| 摘要 |
PURPOSE:To improve the pilot signal eliminating characteristic, by applying a composite signal and a signal converting the waveform of a rectangular wave signal having the same frequency as that of a pilot signal to a non-inverting and an inverting input terminal of an operation processing circuit. CONSTITUTION:The composite signal of an FM stereo broadcast inputted to a terminal 15 passes through a buffer 16, then it is inputted to the non-inverting input of the operation processing circuit 17 and to a phase detector 25. An output signal of the detector 25 is inputted to a PLL circuit consisting of an LPF26, a DC amplifier 27, a voltage control oscillator 28, and frequency dividers 29, 30, and an output of the frequency divider 30 is inputted to a phase detector 24 through a frequency divider 31 generating a rectangular wave of a pilot PL signal frequency having different phase from the output of th frequency divider 30 by 90 deg.. An output of the circuit 17 is inputted to a decoder 18 separating an L and an R signal, the phase detection is attained with a rectangular wave from the frequency divider 31 by the detector 24, a converting signal synchronized with the PL signal is outputted from a waveform converter 21 and inputted to an inverting input of the circuit 17. Thus, a signal eliminated with the PL signal is obtained from the circuit 17. |
