| 摘要 |
PURPOSE:To improve the reliability of a transmitter by alternating the inuse mode of a transmitter with the stand-by mode even in unmodulated and noncarrier states, by discriminating the contents of a modulation output. CONSTITUTION:The system is equipped with BPF12 which extracts a modulation output of a digital signal by using the carrier frequency of oscillator 4 as a center frequency, supervising circuit 11 which exercises a level supervision by detecting the extracted modulation output to discriminate the cases that electric power spectra reside, that while electric power spectra disappear, only a carrier wave reside, or that only inband noises reside, and control circuit 14 which exercises switching control over inuse/stand-by equipments by its supervision output. Then, when spectra of the carrier wave only or inband noises only are discriminated, change- over unit 10 is controlled to change the transmitter from inuse equipment 13-1 over to stand-by equipment 13-2. |
