| 摘要 |
PURPOSE:To omit an oscillator, a modulator, a frequency converter, an excitation amplifier, a filter, etc. and to attain the miniaturization and economical properties of a radio communication device, by changing the circuit constitution of a transmitter for a duplex communication system having different transmission reception frequencies. CONSTITUTION:The conventional transmission oscillator, frequency converter, BPF, excitation amplifier, BEF, etc. are omitted. The modulation signal of a modulation controller 17 is distributed to both a modulator 18 of the 2nd local oscillator 6 and a frequency synthesizer 25 by a branching circuit 27 to give the modulation of the same amplitude to the modulator 18 and the synthesizer 25. The synthesizer 15 which oscillates the transmission frequency also oscillates a carrier frequency by an indication of a controller 26. This oscillation output is branched into two parts by a branching circuit 28. One of these two branched outputs is supplied to a power amplifier 24 via a switch circuit, and the other output is supplied to a frequency converter 3 of a receiver in the form of a frequency of the 1st local oscillator. An amplifier 24 amplifies the excited power given from the synthesizer 25 and delivers it to an antenna 1. The other output (b) of the circuit 27 is applied to the modulator 18 of the 2nd local oscillator 6 to be modulated to the 2nd local oscillation frequency. |
