Patent ID: 7994912

Claim:
An intrusion-object detection system, comprising: a radio-wave radiation unit, in a cable form with one end thereof as a feed end and the other end thereof as a far end, configured to radiate as a radio wave, a transmission signal on which a spread spectrum signal is superimposed fed into said radio-wave radiation unit from the feed end; a radio-wave reception unit configured to receive the radio wave, in a cable form, placed approximately in parallel with said radio-wave radiation unit; a signal reception unit configured to receive the transmission signal as a reception signal, connected to an end, on the feed-end side, of said radio-wave reception unit; a signal demodulation unit configured to define the reception signal so as to calculate the amplitude of the reception signal with respect to range bins each correlated with a distance from a position of the feed end, on said radio-wave radiation unit and said radio-wave reception unit, based on a correlation between a time-delay from transmission time of the transmission signal until reception time of the reception signal and the distance along a transmission path according to route's positions on said radio-wave radiation unit and said radio-wave reception unit in the transmission path through which the transmission signal passes after its transmission until reception as the reception signal, by comparing a code sequence of a spread spectrum signal extracted from the reception signal with a code sequence of a spread spectrum signal in the transmission signal; and a malfunction distinguishing unit configured to determine that a malfunction is present in either said radio-wave radiation unit or said radio-wave reception unit, when, comparing the reception signal with the transmission signal for the range bins corresponding to the far end, a level of amplitude reduction in the reception signal exceeds a predetermined ratio.