PURPOSE: To simplify the unit and to make use of the frequency band effectively by increasing the number of subscribers by generating FT(frequency-time) addresses free from mutual interference by adding a fixed address appending circuit at a transmission side and a frequency discriminating circuit at a reception side.

CONSTITUTION: Through switch 3, a pulse-coded signal from modulator 2 is supplied to address appending unit 4 or 5 for FT matrixes, bearing a double relation in terms of the number of time slots of one frame consisting of the same time length and the same frequency band and a one-half relation in terms of the number of frequency slots, and their outputs are mixed 10 via high-frequency gates 6 and 7 consisting of n and n/2 frequency slots respectively before being transmitted. On the other hand, a received signal is converted 15 into IF and then supplied to group 18 of m frequency discriminating circuits and group 19 of envelope detecting circuits by way of an m=n/2 number of IFAs 17 that correspond to every two adjacent frequency slots of the FT matrixes and futher address-decoded at 20 and 21 before being demodulated at 23.