Environmental test switch for intruder detection systems

Claim 2

For use in a detection system for sensing the occurrence of an event of interest amid a variety of sources of background noise, the system comprising means for distinguishing electrical signals characteristic of the event of interest from electrical signals characteristic of background noise, and means for activating an alarm in response to the sensing of an electrical signal having an amplitude which rises above or drops below a predefined threshhold level, the improvement comprising, in combination: switch means for temporarily increasing the level of sensitivity of the system by a predesired factor above an initial level; and means for setting the sensitivity of the system, at a time when said switch means is effective to produce such a temporary increase in sensitivity, to a level at which electrical signals characteristic of background noise have an amplitude substantially equal to said threshold level of the activating means, whereby the system sensitivity, upon being unaffected by said switch means, is set at a level which provides a predesired margin of safety against alarming due to background noise signals.

Claim 3

In an intruder detection system comprising means for transmitting energy waves into a region wherein intrusion is to be detected; means for receiving said transmitted energy waves upon being reflected and/or modified by objects within said region and for converting said energy waves into a first electrical signal having an instantaneous amplitude and frequency proportional to that of the resultant energy wave received; detecting means for generating a second electrical signal in response to changes in said first electrical signal; integrating means operatively coupled to said detecting means for smoothing out rapid variations in the amplitude of said second electrical signal, the degree of such smoothing being governed by the time constant of the integrating circuit, and a threshold sensor operatively coupled to said integrating means for activating an alarm when the amplitude of said second electrical signal exceeds a predefined threshold level, the improvement comprising, in combination: switch means operatively coupled to said integrating means for temporarily decreasing the time constant of said integrating means by a predetermined factor, thereby temporarily increasing the sensitivity of the system by a predefined factor; and means operatively coupled to said receiving means for adjusting the amplitude of said first electrical signal, at a time when said switch means is effective to temporarily increase the system sensitivity and when no intruder is present in said region, to a level at which background noise is just effective to produce alarm activation, whereby the system sensitivity, upon being unaffected by said switch means, is set at a level which provides a predesired margin of safety against alarming due to signals characteristic of only background noise.

Claim 4

In an intruder detection system comprising means for transmitting energy waves into a region wherein intrusion is to be detected; means for receiving said transmitted energy waves upon being reflected and/or modified by objects within said region and for converting said energy waves into a first electrical signal having an instantaneous amplitude and frequency proportional to that of the resultant energy wave received; detecting means for generating a second electrical signal in response to changes in said first electrical signal; integrating means operatively coupled to said detecting means for smoothing out rapid variations in the amplitude of said second electrical signal, the degree of such smoothing being governed by the time constant of the integrating circuit, and a threshold sensor operatively coupled to said integrating means for activating an alarm when the amplitude of said second electrical signal exceeds a predefined threshold level, the improvement comprising, in combination: switch means operatively coupled to said integrating means for temporarily decreasing the time constant of said integrating means by a predetermined factor, thereby temporarily increasing the sensitivity of the system by a predefined factor; and means operatively coupled to said receiving means for adjusting the amplitude of said first electrical signal, at a time when said switch means is effective to temporarily increase the system sensitivity and when no intruder is present in said region, to a level at which background noise is just effective to produce alarm activation, whereby the system sensitivity, upon being unaffected by said switch means, is set at a level which provides a predesired margin of safety against alarming due to signals characteristic of only background noise.

Claim 5

In an intruder detection system comprising means for transmitting energy waves into a region wherein intrusion is to be detected; means for receiving said transmitted energy waves upon being reflected and/or modified by objects within said region and for converting said energy waves into an electrical signal having an instantaneous amplitude and frequency proportional to that of the resultant energy wave received; threshold-sensing means operatively coupled to said receiving means for transmitting an alarm activating signal in the event the amplitude of said electrical signal exceeds a predefined threshold level; the improvement comprising, in combination; switch means operatively coupled to said threshold-sensing means for temporarily reducing the threshold level of said threshold-sensing means by a predetermined factor, thereby temporarily increasing the sensitivity of the system by said predetermined factor; and means operatively coupled to said receiving means for adjusting the amplitude of said electrical signal, at a time when said switch means is effective to temporarily increase the system sensitivity and when no intruder is present in said region, to a level at which background noise is just effective to produce alarm activation, whereby the system sensitivity, upon being unaffected by said switch means, is set at a level which provides a predesired margin of safety against alarming due to signals characteristic of only background noise.

Claim 6

In an intruder detection system comprising means for transmitting energy waves into a region wherein intrusion is to be detected; means for receiving said transmitted energy waves upon being reflected and/or modified by objects within said region and for converting said energy waves into an electrical signal having an instantaneous amplitude and frequency proportional to that of the resultant energy wave received; threshold-sensing means operatively coupled to said receiving means for transmitting an alarm activating signal in the event the amplitude of said electrical signal exceeds a predefined threshold level; the improvement comprising, in combination; switch means operatively coupled to said threshold-sensing means for temporarily reducing the threshold level of said threshold-sensing means by a predetermined factor, thereby temporarily increasing the sensitivity of the system by said predetermined factor; and means operatively coupled to said receiving means for adjusting the amplitude of said electrical signal, at a time when said switch means is effective to temporarily increase the system sensitivity and when no intruder is present in said region, to a level at which background noise is just effective to produce alarm activation, whereby the system sensitivity, upon being unaffected by said switch means, is set at a level which provides a predesired margin of safety against alarming due to signals characteristic of only background noise.