PURPOSE: To decode an address code and to transmit it assuredly, by addedly averaging an address code which is repetitively transmitted to a central processor from a taxi calling area or an address code signal which is repetitively transmitted to a taxi from the central processor.

CONSTITUTION: An address code signal, etc. generated from a code signal generator 11 is series coded and delivered to an AM modulating part 14 at and after a time and for a time prescribed by the time information given from a timepiece 13 and in a prescribed frequency. The part 14 converts a carrier signal of frequency fc sent from a carrier oscillating circuit 15 into intermittent signals by a series coding signal fd and then transmitted from an antenna 17 through a driving circuit 16. At the receiving side the transmitted electric waves are extracted by an antenna 18, a pre-selecting amplifier 19, a mixer 20, a local oscillator 21, an intermediate frequency amplifier 22 and a wave detector 23 (an existing superheterodyne system) respectively and digitized via an A/D converter 24. This digitized wave is supplied to an averaging processing circuit 25. The circuit 25 performs averaging at and after a prescribed time and in a prescribed frequency for the address code signal and then applies this code signal and then applies this code signal to a code decoder 27.