| 摘要 |
PROBLEM TO BE SOLVED: To provide a wireless communication system that eliminates the need for a control channel for frequency control and identifies a transmission channel in a short time so as to suppress excess power consumption and to provide an alarm system utilizing the wireless communication system, a sensor information transmitter and a monitor device. SOLUTION: A master unit reception section simultaneously receiving FSK signals of a plurality of channels conducts simultaneous demodulation processing as described below; a mixer 60 converts an RF signal received via an antenna 60 into a signal with a base band frequency, a low pass filter LPF extracts a received signal including all channels possibly used for the transmission, an output signal from the LPF is analog/digital converted, the frequency is analyzed on the basis of an FFT(Fast Fourier Transform) algorithm, and a power spectrum of the frequency region including all the channels is obtained, the presence/absence of the signal by each channel is discriminated, and when the signal exists, 0/1 discrimination subjected to FSK modulation is discriminated. |
