WIRELESS OPENING PART OPENING/CLOSING DETECTION SYSTEM

PURPOSE:To obtain a means operating excellently also under comparatively noisy circumstances and when the distance of a controller side antenna/an opening and closing detection sensor part is comparatively far, in a wireless opening part opening/closing detection system for concentratedly performing a remote monitoring of the opening/closing states of plural opening parts of a building such as windows and doors, etc. CONSTITUTION:A quasi-synchronization and detection is performed for the reception signal of the receiver 7 of a controller part C by first and second reference signals controlled so that they may have an orthogonal relation with each other by an oscillator 6 and a pi/2 phase converter 21. Two orthogonal reception signals obtained by the quasi-synchronization and detection are sampled by a prescribed cycle, an A/D conversion is performed for the signals by each A/D converter 23, they are made digital values and these values are stored in a memory 24. The deviation DELTAf of an echo and the oscillator 6 is detected by performing an FFT processing by an FFT arithmetic unit 26, the oscillator 6 is controlled based on this deviation, and an oscillation frequency f is made to coicide with the frequency of the echo.