| 摘要 |
<p>A scanning intrusion detection device which is capable of monitoring a large volume of either interior or exterior space from a single relatively inexpensive unit. This intrusion detection device comprises a radiation emitter arranged to scan a beam of infrared radiation about a field of view and means for receiving the radiation of the beam reflected from the field of view. The receiving means is arranged to generate a signal indicative of the distance from the device at which the beam has been reflected for each of a plurality of azimuthal sectors of the field of view during a selected time period. Means is also provided for storing a plurality of reference signals which are indicative of the distance of reflection of the beam from each azimuthal sector of the field of view during a reference time period. Further means is provided for comparing the signals from a selected time period with the reference signals and for generating an output signal if one of the signals is different from the respective reference signal.</p> |
