| 摘要 |
<p>A radio relay method for digital communication applying a heterodyne relay system consisting of terminal stations and relay stations each having radio repeaters (50, 51, 52) using radio frequency of microwave or millimeter wave. The radio repeater usually receives a desired wave being a correct wave for a route to which the terminal and relay stations belong. However, the radio repeater may happen to receive an undesired wave, whose level is beyond the threshold level of a squelch circuit (4) in the radio repeater, produced by interference with a radio wave from an adjacent different route for example. When the desired wave decays due to fading for example and the undesired wave becomes dominant, the terminal station of the route finds it impossible to discriminate which relay station has a fault. The radio repeater applying the present invention has means (5, 13) for detecting a received pilot signal from the received undesired wave; means (16) for judging whether the received pilot signal is incorrect for the route; means (4) for stopping the receivedmain signal in the received undesired wave; and means (7, 9) for sending only a supervisory signal to successive relay stations with a correct pilot signal generated by the radio repeater (means 20,21), so that the terminal station can detect the pilot signal and recognize the state of the relay station from the supervisory signal.</p> |
