PURPOSE: To make a mobile equipment small in size by utilizing a difference from transmission reception operating timings of the TDMA or TDD communication so as to use one orthogonal demodulator for both the transmission and reception thereby integrating the circuit.

CONSTITUTION: A branch output T being a transmission power of an output of a power amplifier PA5 receiving an original modulation signal of a transmission system 100 or an IF conversion output R of a reception mixer RX8 applying frequency converting an input orthogonal modulation wave to a reception system is selected by a changeover switch 300 for predetermined transmission reception timing. When an orthogonal demodulator QDEM9 of a reception system 200 is connected to a contact T, the branch output T being a transmission output of a sender side is received and orthogonal-demodulated and base band outputs I", Q" are fed back to an adder ADD3 at the input of the orthogonal modulator QMOD4 to compensate nonlinear distortion generated from the power amplifier PA5. When the switch 300 is thrown to the position of a contact R, an orthogonal modulation signal of an intermediate frequency IF being an output of a receiver RX8 is received and orthogonally demodulated to obtain base band outputs I", Q" and they are used both for the transmission system 100 and the reception system 200.