| 摘要 |
<p>PURPOSE:To make a device compact and light in weight by preventing an interference between a demodulating circuit for transmission and the VCO of a PLL for channel setting. CONSTITUTION:This device is equipped with a transmitting circuit 10, receiving circuit 20, and PLL 40 which supplies an oscillation signal for channel setting therefor. The transmitting circuit 10 is equipped with an FM modulating circuit 12 which converts a signal to be transmitted into an FM signal S12, and a mixer circuit 13 which frequency-converts the FM signal S12 into the signal of an incoming channel. The receiving circuit 20 is equipped with a first mixer circuit 24 which frequency-converts a signal S21 of an outgoing channel into a first intermediate frequency signal S24, circuit 27 which frequency-converts the first intermediate frequency signal S24 into the second intermediate frequency signal, and FM demodulating circuit 32 which FM-demodulates the second intermediate frequency signal. The carrier frequency f12 is set to be an integer multiple of the frequency of the sum of the intermediate frequency F24 of the first intermediate frequency signal S24 and the difference between the frequencies of the incoming and outgoing channels.</p> |
