Signalling system with ambient condition reference monitoring

• US 5,051,723 A
• Filed: 09/29/1989
• Issued: 09/24/1991
• Est. Priority Date: 09/29/1989
• Status: Expired due to Term

• Current Assignee: Erudite Systems, Inc.
• Original Assignee: George E. Long
• Inventors: Kenney, Martin J., Long, George E., Asmussen, Daniel R.
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US07/414,701
• Time in Patent Office: 725 Days
• Field of Search: 340/566, 340/429, 340/683, 340/587
• US Class Current: 340/566
• CPC Class Codes: G08B 13/1436 with motion detection
• CPC Class Codes: G08B 13/1672 using sonic detecting means, e.g. a microphone operating in the audio frequency range

Abstract

A self-contained theft and vandalism deterrent system for equipment security includes sensors (12) for detecting conditions to which an alarm (24, 26, 28, 50) is responsive. The analog signals from the sensors (12) are serially delivered by a multiplexer circuit (16) when they are then directed to a network (20) for conversion to digital signals. The digital signals are delivered to a micro processor (22) where the signals are evaluated to determine if an alarm condition exists. The sensing means (12) include sound and vibration detectors for monitoring the ambient envelope. The micro processor (22) includes built in reprogramming and comparator circuits for varying the level at which a given condition will trigger an alarm response.

Claims

1. An alarm system for generating an alarm signal responsive to a sensed condition under surveillance wherein said sensed condition is compared to a reference condition for determining if an alarm signal is to be generated, said system comprising in combination,

(a) alarm signal generating means,

(b) ambient condition monitoring means including first sensing means for monitoring at least one given ambient condition and for generating a reference signal representing said ambient condition,

(c) second sensing means for generating a surveillance signal responsive to said sensed condition under surveillance,

(d) and signal comparing means for comparing said reference signal and said surveillance signal, said alarm signal generating means being actuated by a sensed condition signal if said surveillance signal exceeds said reference signal by a predetermined amount,

whereby the alarm system is activated when a sensed condition occurs which is outside the ambient envelope, thereby providing an alarm system with a reference signal which is constantly changed in response to constantly changing ambient conditions.

2. The alarm system according to claim 1 wherein said ambient condition monitoring means includes ambient noise monitoring means for monitoring ambient noise levels.

3. The alarm system according to claim 1 wherein said first and second sensing means generate electrical analog signals which are converted to electrical digital signals.

4. The alarm system according to claim 3 wherein said second sensing means detect a predetermined frequency range of acoustical disturbances, and wherein network means are included for separating the acoustical disturbances into frequency bands and outputting a discrete output voltage analog signal proportional to the disturbances sensed in each frequency band.

5. A theft and vandalism alarm system for an item of equipment, said system including electronic control means comprising,

(a) an alarm signal generating means including at least one sensor means for transmitting at least one surveillance signal representative of a condition under surveillance sensed by said sensor means,

(b) ambient condition monitoring means for monitoring at least one given ambient condition and for generating a reference signal representing said ambient condition,

(c) said electronics including first network means for accepting said surveilance signals and separating the same into a predetermined group of frequency ranges, the signals in each of said group of frequency ranges being converted to a discrete signal,

(d) second network means for receiving each of said discrete signals and said reference signals and sequentially outputting the same, and

(e) a microprocessor receiving the output of said second network means for determining whether said frequency range signals represent an alarm condition, said microprocessor being adapted to activate said alarm signal generating means if frequency range signals received therein are evaluated to exceed a predetermined level.

6. The theft and vandalism deterrent system according to claim 5 wherein said discrete output signals are voltage analog signals.

7. The theft and vandalism deterrent system according to claim 5 and wherein a third network means is provided for receiving and converting said discrete signals into digital signals.

8. An alarm system for generating an alarm signal responsive to a sensed condition wherein said sensed condition is compared to a reference condition for determining if an alarm signal is to be generated, said system comprising in combination,

(a) alarm signal generating means,

(b) ambient condition monitoring means including a first sensing means for sampling at least one given ambient condition at predetermined intervals and for generating a reference signal representing an ambient reference condition,

(c) second sensing means for generating at least one surveillance signal responsive to a sensed condition under surveillance,

(d) said alarm system including first network means for accepting said at least one surveillance signal and separating the same into a predetermined group of frequency bands, the surveillance signals sensed in each of said bands being converted to a discrete signal,

(e) second network means for receiving each of said discrete signals and said reference condition signal and sequentially outputting the same, and

(f) microprocessor means for receiving the output of said second network means for determining whether said discrete signals represent an alarm condition, said microprocessor means being adapted to activate said alarm signal means if the discrete signals received therein are evaluated to exceed a predetermined level.

9. A theft and vandalism deterrent system for an item of equipment including a self contained electronics control housing adapted to be secured to said item of equipment at a predetermined location thereon and being adapted to be connected to an external power source as well as having self contained pwoer, said system further including,

(a) a plurality of monitoring means for said system which are connected to said control housing including a plurality of first sensing means for transmitting a plurality of signals representative of constantly changing conditions sensed by said monitoring means to the electronics within said control housing in the form of electrical analog signals to establish constantly changing reference levels,

(b) second sensor means for generating at least one surveillance signal responsive to a sensed condition under surveillance,

(c) said signal including at least a noise level condition which, if above a predetermined reference level, results in generation of an alarm and, if below said reference level, results in generation of no alarm, said reference level representing ambient noise conditions and being changed by said electronics to conform to continuous changes in ambient noise in proximity to said item of equipment,

(d) said electronics including first network means for accepting said surveillance signals and separating the same into a predetermined group of frequency bands, the surveillance signals sensed in each of said bands being converted to a discrete voltage analog signal,

(e) second network means for receiving each of said discrete voltage analog signals and said reference level signals and sequentially outputting the same,

(f) third network means for receiving and converting said discrete voltage analog signals to digital frequency range signals, and

(g) a microprocessor receiving the output of said second network means for determining whether said digital signals represent an alarm condition by comparing said digital signals with said reference level, said microprocessor being adapted to activate any one of a plurality of alarm responses if digital signals received therein are evaluated to exceed said reference level by a predetermined amount.

10. An alarm system for generating an alarm signal responsive to a sensed condition under surveillance wherein said sensed condition is compared to a reference condition for determining if an alarm signal is to be generated, said system comprising in combination,

(a) alarm signal generating means,

(b) ambient condition monitoring means including first sensing means for sampling at least one given ambient condition at predetermined intervals and for generating a reference signal representing an ambient reference condition,

(c) second sensing means for generating a surveillance signal responsive to a sensed condition under surveillance

(d) signal comparing means for comparing said reference signal and said surveillance signals,

(e) said alarm signal generating means being actuated by a sensed condition signal if said surveillance signal exceeds said reference signal by a predetermined amount,

whereby the alarm system is activated when a sensed condition occurs which is outside the ambient envelope, thereby providing an alarm system with a reference signal which is changed with changing ambient conditions.

11. The alarm system according to claim 10 wherein said signal comparing means comprises programmable data processing means.

12. A method of detecting and signalling levels of a given condition associated with an area under surveillance which fall outside predetermined parameters comprising the steps of;

monitoring ambient levels of said given condition and generating a reference signal representing an existing ambient envelope reference condition,

sensing the given condition in the area under surveilance and generating a separate surveillance signal representative of the sensed condition in the area of surveillance,

using a programmable data processor to compare said reference signal and said surveillance signal and to actuate a response signal when a comparison of the surveillance and reference signals indicates the level of the given condition in the area under surveillance is outside said predetermined parameters according to a model programmed into said data processor.

13. The method according to claim 12 wherein said given condition comprises mechanical disturbances, said method including the steps of;

converting said mechanical disturbances to electrical analog signals comprising said surveillance signals, and

separating the surveillance signals into frequency bands and outputting a discrete voltage analog signal proportional to the surveillance signals in each frequency band.

14. The method according to claim 13 including the step of;

converting said electrical analog signals to electrical digital signals.

15. The method according to claim 13 wherein said mechanical disturbances comprise acoustical disturbances.