| 摘要 |
PURPOSE:To set a transmission and a reception frequency independently by improving spurious characteristics, by providing digital frequency synthesizers for transmission and reception, respectively. CONSTITUTION:A digital frequency synthesizer 24 composed of a VCO25, a variable frequency divider 26, a phase comparator 27, and an LPF28 is provided on a transmitting circuit side. This synthesizer 24 is constituted by using a control part 3 and a reference oscillator 5 in common to a digital frequency synthesizer 8. Then, a demosulated signal collected by a microphone 23 is processed by amplification 17 and then applied to the VCO25 to impose FM modulation upon a transmitted signal. |
