| 摘要 |
PURPOSE:To secure demodulation for the stereo wave in the monophonic from through the same operation as the synchronous AM detection of the stereo composite signal by providing the low pass filter in front of the synchronous AM detection part for the stereo demodulation. CONSTITUTION:In the case of the stereo demodulation, the sample holding is given to either peak value of the stereo composite signal via the sampling signal synchronizing with the pilot signal to obtain the waveform B of Fig.(a). Waveform B is then averaged. In case the composite signal is demodulated into the monophonic form, the composite signal is made to pass through the low pass filter to obtain the signal in which the subcarrier component of 38kHz is attenuated. At the same time, the delayed phase is secured up to about 90 deg. for the subcarrier signal, and the sample holding is given to the point corresponding to nearly the middle between both peak value of the subcarrier signal via the sampling signal to obtain waveform B shown in Fig.(b). This waveform is then averaged to obtain the signal in which signals L and R are added together. |
