| 摘要 |
PURPOSE:To adapt an antenna to radio conditions by determining the antenna selective switching level in accordance with the degree of the occurrence of the multipath distortion of the antenna, which a receiver uses for reception, to switch the antenna to the other antenna in accordance with the amplitude of the distortion. CONSTITUTION:The antenna is selectively switched to an antenna 2 or 3 by an antenna selecting circuit 1 of a diversity receiver, and the reception signal is amplifier and detected by a front end circuit 4 and an IF amplifier 5, and the output is applied to a low frequency amplifier 6 and a multipath distortion detector 7. The multipath distortion of the antenna 2 or 3 used for reception at present is detected by this detector 7, and the amplitude level of the multipath distortion is detected by a distortion level detector 8. The pulse from the detector 8 has the waveform shaped to prescribed magnitude and width by a waveform shaping circuit 9 to determine the selective switching level of antennas 2 and 3. A toggle FF10 is triggered by the circuit 9, and the circuit 1 is controlled by the output of the FF10 to switch the antenna 2 or 3 to the antenna 3 or 2. |
