| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce a packaging area and to miniaturize an equipment by providing a filter means for eliminating the unrequited waves of transmission intermediate frequency signals and reception frequency signals. SOLUTION: In reception, signals received through an antenna 1 are band- limited by an RF filter 2 and supplied to a mixer 4. The output signals of the RF filter 2 are mixed with local signals from a UHF frequency synthesizer 3 in the mixer 4 and converted into reception IF signals. The reception IF signals are supplied through a changeover switch 5 to an IF filter 6 and the unrequired waves are eliminated there. Further, they are supplied through the changeover switch 5 to a quadrature demodulator 8 and quadrature demodulated by the signals from a VHF frequency synthesizer 7 and demodulation signals are outputted to the circuit of a poststage. A timing control part 13 controls the changeover swtich 5 so as to connect the mixed 4 and the IF filter 6 and controls the changeover swtoich 12 so as to connect the IF filter 6 and the quadrature demodulator 8 in reception.</p> |
