| 摘要 |
PURPOSE:To improve the deterioration of high frequency separation resulting from the addition of a high blend circuit by controlling the 1st and 2nd demodulation levels by control signals that correspond to levels of high frequency parts of the 1st and 2nd channel demodulated signals. CONSTITUTION:A composite signal from the FM detector is demodulated by MPX demodulator 1 into right and left channel signals before being outputted. Parts of those outputs are supplied to envelope detectors 10 and 11 via HPFs 8 and 9 to obtain envelope detection outputs of high frequency parts of the right and left channel signals. In the above-mentioned constitution, when switch SW1 of the high blend circuit is closed, mutually antiphase high frequency noise components included in the right and left channel signals are removed by capacitor C by being blended. At the same time, the separation of the high frequency part deteriorates, but gains of VCAs 6 and 7 are controlled by the outputs of detectors 10 and 11, so that the deterioration of separation can be improved. |
