| 摘要 |
PURPOSE:To attain invariably excellent reception by deciding the carrier level of a stereophonic signal by a deciding circuit and then by using the decided carrier level to change-over an input to a high-frequency amplifier depending upon whether mutual interference occurs or not. CONSTITUTION:The 1st signal path 1 that leads an input signal from an antenna to direct high-frequency amplifying circuit 3 and the 2nd signal path 2 that connets it to circuit 3 via multistage tuning circuit 2' are provided and it is made possible to change paths 1 and 2 over through change-over circuit 10. An output signal from this amplifying circuit 3 is applied to IF amplifier 6 via mixer 4 and its IF signal is applied to FM demodulator 7 and also to deciding circuit 9 to decide a carrier level. At a mutual modulation disturbance level, tuning circuit 2' connected to the path 2 side excludes modulation disturbance to set an excellent reception state and when no mutual modulation is not performed, a connection to the path 1 side to attain excellent reception with sensitivity. |
