| 摘要 |
PURPOSE:To eliminate the production of buzz tone, by making the gain of an IF amplifying circuit sufficiently and relatively greater, taking the video carrier as the center and making flat the delay characteristics in the frequency range from the voice carrier to the video carrier. CONSTITUTION:The 2nd IF amplifying circuit 6 for voice to which the output of a tuner 1 is applied is applied is provided separately with the 1st IF amplifying circuit 2 for video use, the output of the circuit 6 is in intercarrier detection 7, and the intercarrier signal picked up at a BPF8 from the output is given to a voice demodulation circuit 9. In the circuit 6, the gain within the range of + or -0.75MHz taking the video carrier P as the center is made sufficiently greater relatively so that the delay characteristics can be made flat in the frequency range from the voice carrier to the video carrier P. According to the output of the intercarrier detection circuit 7, AGC is given to the circuit 6. The production of buzz tone due to the slope of the Nyquist and group delay characteristics of the IF amplifying circuit is eliminated. |
