Abstract: Present day intrusion detection systems frequently cause false alarms by mistaking occupants as intruders, and it is desirable to reduce such false alarms. This invention comprises a processor that employs various software algorithms. The processor receives signals over temporal periods and software algorithms statistically discern various activities, thereby reducing false alarms and detection failures. The software algorithms are adaptive to the level of detected activity such that a rate of false alarms may be predetermined. As such, the processor and software algorithms comprise an artificial intelligence system. This artificial intelligence system may be employed in intruder and vehicle alarm systems composed of a multiplicity of detectors and within such detectors. A second aspect of this invention is an improved infrasound detection method that may be employed in such artificial intelligence.

Abstract: A portable alarm device (100) for guarding a car (200) or another mobile object having a lockable compartment against theft or burglary, comprising: a housing (1) having at least one opening (2) and a microphone (4) therein for detecting infrasound; electrical circuitry (5) within housing (1) for processing signals and for transmitting an alarm signal on the detection of a forced entry; and a built-in power supply (7), i.e. batteries. The housing (1) is provided with steering features (2,9,11) for ensuring the existence of an unobstructed air path to opening(s) (2) regardless of the orientation and position assumed by the alarm device (100) being put rapidly into the coupe of the car by a staff member. The steering features may be legs (9) proximate to opening (2), a grating (10) surrounding opening (2), or alternatively surrounding the entire housing (1), or may be comprised of a number of openings in housing (1), spaced around the housing.