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HIGH FREQUENCY RETURN TRANSMISSION-RECEPTION CIRCUIT AND RADIO TRANSMISSION-RECEPTION EQUIPMENT PROVIDED WITH THE SAME
HIGH FREQUENCY RETURN TRANSMISSION-RECEPTION CIRCUIT AND RADIO TRANSMISSION-RECEPTION EQUIPMENT PROVIDED WITH THE SAME
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机译：高频回波收发电路和具有该收发器的无线电收发设备
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摘要
PROBLEM TO BE SOLVED: To easily execute the high frequency return test of a present station by selecting a second band filter for passing a transmission frequency signal, at the high frequency return test. SOLUTION: At a high frequency return test, a high frequency return operation switch 20 is turned on by a high frequency return control signals 21, and a frequency shifter 14 is operated. A transmission signal sent to the frequency shifter 14 by a transmission side directional coupler 15 is shifted to, for example, a frequency two channels away from the frequency of a reception signal, and guided to a reception system by a reception side directional coupler 16 and inputted through an isolator 19 to a 1st reception converter 24. Then, a high frequency switch 32 turns on the 1st reception converter 24 and a band-pass filter(BPF) 31 according to the high frequency return control signal 21. The central frequencies of BPFs 31 and 26 are separated by two channels, and the return signal of the present station is passed through the BPF 31 without being attenuated.
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