| 摘要 |
PURPOSE:To reduce the cost of equipment, to obtain small-size, lightweight constitution, and to reduce power consumption by inputting a carrier from a transmitter to the frequency converting circuit part of a receiver, and then performing frequency conversion and control. CONSTITUTION:In a duplex transceiver device, a transmitting circuit part B amplifies a voice, etc., inputted from a microphone 25 through a low-frequency amplifier 24 for modulation and then inputs the result to a modulator 23 for frequency shifting, and after the oscillation frequency of a crystal oscillator 22 is modulated, three-fold multiplication 4 and power amplification 21 are performed to apply the result to an antenna common device 31 and a receiving circuit part A through a BPF1. At the reception part A, a radio wave received by an antenna 32 is passed through a BPF1 and amplified by a high frequency amplifying circuit 2, whose output is sent to a mixer 3. The mixer 3 receives a frequency from the transmission part B through an attenuator 17 to mix it with the reception frequency from the circuit 2 for conversion into an intermediate frequency, and then performs amplification 6 and amplitude limitation 7 to input the result to a frequency discriminator 8. The discriminator 8 demodulates the signal from the limiter 7 into an audio frequency and performs low frequency amplification 9 to drive a speaker 10 by the resulting signal. |
