| 摘要 |
PURPOSE:To cancel crosstalk components of a modulation signal perfectly in a simultaneous transmitting and receiving communicator using a channel oscillator and the first local oscillator (LO) in common, by making the spectrum of the second local oscillator signal and the first IF signal equal. CONSTITUTION:A channel oscillator OSC output of which is modulated by output of an aural signal circuit AF is used in common with an LO1 of a receiver RX and the output is inputted to the first mixer MIX1. On the other hand, a modulation signal is inputted to a level adjusting circuit VOL, and a phas shifter PS, and an output of the second local oscillator LO2 modulated by the output is inputted to the second mixer MIX2 of the receiver RX. The center frequency of a filter BPF1 is conformed with that of the second local oscillator LO2, and its passing band is made equal to the first intermediate frequency filter IF1. Consequently, the modulation spectrum of an LO2 becomes substantially the same with that of the filter IF1. Accordingly, modulation signal components detoured from the channel oscillator OSC through the first mixer MIX1 are canceled perfectly. |
