| 摘要 |
<p>PURPOSE:To enable the automatic removal of a blocking state, by detecting the blocking state and by controlling a gain so that AGC for a linear amplifier be matched with a detection signal of a reception signal. CONSTITUTION:When azimuth distance signal 502 is not in a locked state, an input of a peak hold circuit 6 is made to be a detection signal 301 only for a prescribed time. At the time of a blocking state, on the contrary, the detection signal 301 is at a large level. Therefore an AGC circuit 7, to which the detection signal 301 is inputted through the peak hold circuit 6, operates to lessen gains of linear amplifiers 1 and 2 and outputs an AGC voltage 701 so as to lower the level of the detection signal 301. Consequently, the level of the detection signal 301 is lowered, a decoder circuit 4 operates also normally, and an azimuth distance computing circuit 5 can be locked at a reception signal. Accordingly, the blocking state is also removed. After a prescribed time passes, a return is made to an AGC system of a regular receiver. By this method, the automatic removal from the blocking state is enabled.</p> |
