| 摘要 |
PURPOSE:To realize a radio receiver which has high sensitivity and also is excellent in its radio interference eliminating characteristic, by detecting an output of high frequency of a radio receiving part, discriminating whether a disturbing radio wave exists or not, and switching automatically whether a disturbing radio wave eliminating filter is inserted into an antenna inputting circuit or not. CONSTITUTION:When there is no disturbing radio wave, an input terminal and an output terminal (c) and (b) are connected in a high frequency switching circuit 3. When a disturbing radio wave F is mixed, a state of voltages V2, V3 and outputs Q, Q is inverted, a current i1 flows to a diode D1, this diode D1 conducts and the other diode D2 is cut off. That is to say, when a medium wave band passing filter 2 is inserted between an antenna 1 and a radio receiving part 5, the disturbing radio wave F of the outside of the medium wave band is eliminated. Also, this state is held until the disturbing radio wave F is eliminated, and thereafter, the operation of each part is inverted again and is returned to the previous state. |
