| 摘要 |
PURPOSE:To reduce the sound deflection caused in an antenna switching mode by keeping a fixed level of the control voltage of the ASC (automatic separation control) and the ATC (automatic tone control) which are supplied to a stereo demodulation part even in case the signal level has fluctuation due to an antenna switching action. CONSTITUTION:An antenna switch control part A detects both the reception level and a multi-path and controls a switch circuit 1 for selection of the best antenna. At the same time, the part A reduces the antenna switching sensitivity in case the reception states of both antennas are deteriorated. An MPX demodulation part 4 supplies the ASC and ATC control voltage according to the reception level to improve the S/N. The difference of reception levels is increased between both antennas in case the antenna switching sensitivity is deteriorated less than a fixed level. Thus a control circuit 13 is controlled for compression of the difference between reception signal levels. This prevents the fluctuation of both ATC and ASC voltage. |
