| 摘要 |
PURPOSE:To hold an S/N ratio invariably high by adding auxiliary demodulators corresponding to plural propagation paths and disconnecting the signal to a propagation path which causes deterioration of S/N. CONSTITUTION:The auxiliary demodulators 106 and 206 are provided corresponding to the propagation paths and a signal with the most suitable S/N is selected and applied to an S/N comparator 18. The signal passed through a synthesizer 12, on the other hand, is applied to a demodulator 13, whose output is applied to the S/N comparator 18 similarly, to make the S/N of the signal obtained after the S/N of the propagation path where the signal with the excellent S/N comparison with the S/N of the signal obtained by synthesizing. Then, when the S/N value after the composition is less than the S/N of the propagation path where the signal of good quality is obtained, the signal of a propagation path with a lower carrier level is attenuated greatly and the synthesizer 12 disconnects the propagation path. |
