| 摘要 |
PURPOSE:To execute simultaneous communication by using a signal from an oscillator of a pair of communication devices as a local oscillation frequency of a double superheterodyne system, also using it as a transmitting carrier wave to be modulated, and making the frequencies of those transmitting carrier waves different from each other. CONSTITUTION:An output frequency f1 of a VCO17a of a PLL frequency synthesizer 15a is inputted to a modulating circuit 3a, modulated by a sound signal, and a signal sent out by a transmitting antenna 6a is received by an antenna 7b of the other communication device. Also, an output from the VCO17a is provided as a local oscillation signal to a mixing circuit 22a. A receiving signal of said antenna 7 and the output from the VCO17a are modulated by a mixing circuit 9a for a double superheterodyne system, pass through a mixer 24, are demodulated by a demodulator 12 and received. In the other communication device, an output frequency of a VCO17b becomes different from said f1 by determining a frequency dividing ratio of a frequency dividing circuit 18b. |
