To allow a receiver to receive a radio signal sent from plural repeaters correctly while avoiding a circuit configuration of each repeater from being increased in the radio relay system.
A transmitter 1 applies FSK modulation to a carrier f1 with transmission data of '1'/'0' and converts the modulated data into an optical signal, which is transmitted. A repeater receives the optical signal at a light receiving section 11 to convert the signal into an electric signal with a carrier frequency f1, a demodulation section 12 applies FSK demodulation to the converted signal. An ASK modulation section 13 resets a 1/n (n=8) frequency divider at a rising of demodulation data to allow the 1/n. frequency divider to frequency-divide a master clock of 16MHz into a clock of 2MHz. This clock and the demodulation data are given to an AND gate, from which an ASK modulation wave with a carrier frequency f2(=2MHz) is obtained and it is amplified by an amplifier section 14, a light emitting section 15 converts the amplified signal into an optical signal, which is sent to a receiver.
IKEUCHI TAKANORI
TAKEDA TAKAAKI
NOMOTO TAKESHI
NTT DATA TSUSHIN KK