PURPOSE: To provide an apparatus, wherein the specified delay time is formed by using an SAW(surface acoustic wave) device for a radio identifying card, a timing control corresponding to the delay time is performed in a fixed station, and demodulation is performed.

CONSTITUTION: In a fixed station 7, a timing circuit 1 is provided. The timing circuit 1 has the functions, which clear the state based on the command from a CPU, output the control signal into a PIN diode switch 2, apply a gate at a specified delay time based on the control signal and hold the signal of a comparator 5. In a radio identifying card 8, an SAW device 6, which receives the signal from the fixed station 7 and forms the predetermined delay time, is provided. A means for transmitting the similar signal into the fixed station 7 after the delay time, is also provided. Discrimination is performed at the specified delay time as the feature.