| 摘要 |
<p>PURPOSE:To miniaturize the device by providing a band-stop filter stopping the center frequency of a BPF of a reception section between the modulation circuit of a transmission section and the BPF. CONSTITUTION:The reception wave inputted from an antenna 23 is inputted from an input terminal 1 to pass a 1st BPF 2, and frequency-converted by a frequency modulation circuit 3, then demodulated by a demodulation circuit 5. A voice is outputted from a speaker 25 through an output terminal 6. On the other hand, a voice signal inputted to a microphone 24 is modulated by a modulation circuit 8 through a 2nd input terminal 7 in a transmission section. The output signal of the circuit 8 is power amplified by an output amplifier 9. So as to prevent the signal from entering tone reception section, a band stop-filter 10 stops the center frequency of the BPF 2. Then the signal passes the BPF11 and sent from an antenna 23 through the input terminal 1. Thus, the bidirectional communication device unnecessitating deuplexers can be constructed.</p> |
