77 an if multiplexer h 1 78 an rf mixer 79 which mixes the output of the multiplexer 78 and an output of an rf local oscillator 80 a band pass filter 81 and an amplifier 82 a baseband input is applied to the low pass filter 71 and passes through the above mentioned elements in the above sequence and an rf output is output from the amplifier 82 the receiver portion comprises an rf mixer 86 which mixes the rf input and an output from an rf local oscillator 87 a band pass filter 88 an amplifier 89 an if divider h 2 90 an if mixer 91 which mixes the output of the divider 90 and an output from an if variable frequency oscillator 92 a band pass filter 93 an amplifier 94 a demodulator dem 95 a low pass filter 96 and an amplifier 97 the rf input is applied to the mixer 86 and passes through the above mentioned elements in the above sequence and a baseband output is output from the amplifier 97 in this embodiment as shown in fig6 the multiplexer h 1 78 and the divider h 2 90 are inserted at point c and point d of fig4 respectively and the intermediate frequency oscillators 25 and 46 of fig4 are replaced by the if variable frequency oscillators 75 and 92 respectively in fig5 the rf 1 65 and if 1 67 correspond to the transmitter receiver 11 and the rf 2 66 and if 2 68 correspond to the transmitter receiver 11a of fig3 the transmitter receivers 12 12a and 13 13a can be replaced.