| 摘要 |
PROBLEM TO BE SOLVED: To reduce costs and to improve receiving sensitivity and signal delay characteristic by modulating an output of a 2nd analog modulator into a spread spectrum signal, transmitting it as the high frequency signal of a 2nd frequency, receiving a high frequency signal of a 1st frequency, performing inverse diffusion of the received signal and performing analog demodulation of its output. SOLUTION: An FM modulator 10 modulates information inputted to a slave unit 1 by an FM modulation system. A diffuser 6 further modulates the signal with a PN code generated by a PN code generator 8 of a transmitting side and defines it as a spread spectrum signal. Furthermore, an RF transmitting part 4 performs high frequency conversion and amplification of it and the signal is emitted from an antenna 13 through a filter 2. Meanwhile, a signal transmitted from the slave unit 1 is received by the antenna 29 of a master unit 15, amplified by an RF receiving part 19 through a filter 17, and converted into an IF frequency. The signal from the part 19 is multiplied by the PN code generated by a PN code generator 23 of a receiving side in an inverse diffuser 21. |
