Abstract: An infrared intrusion sensing system comprises a compound lens having a plurality of lines of focus for focusing infrared radiation that enters the system onto a detector, and a window to allow infrared radiation to enter the system and then be focused onto the detector by a set of curvilinear-shaped mirrors. The detector is located near the focal point of the compound lens elements and curvilinear-shaped mirror elements. An enclosure surrounding the detector provides isolation from insect entry and constitutes an insect exclusion enclosure envelope. The enclosure envelope is a protective volume of space for the optical paths between the lens or window and the detector that prevents the entry of objects about 1 mm in diameter or larger which could interfere with the optical paths.

Abstract: Apparatus to rapidly bulk charge a lead acid battery used in a "standby" power supply unit (PSU), or similar equipment containing said function, such as in an alarm panel system, fire panel (system) etc., without increasing the output capacity of the regulated PSU, significantly increasing its dissipation, size or cost, or causing an unacceptable recharge time of (often) several days. The apparatus comprises minimal additional components to provide a bulk charge of approximately 70% capacity to a 65 Ahr battery within 14 hours, while only drawing an average current of approximately 0.4 amp from the regulated PSU.

Abstract: A passive infrared intrusion detection device uses a dual element pyroelectric detector and a housing for surrounding and containing the dual element pyroelectric detector. The housing has a plurality of Fresnel lens elements for gathering infrared radiation from a "look down" volume of space and for focusing the gathered infrared radiation onto the pyroelectric detector. A mask positioned between the plurality of Fresnel lens elements and the detector partially occludes the gathered infrared radiation from the Fresnel lens elements to one of the elements of the dual element pyroelectric detector creating an imbalance in the signal thereby preventing common mode rejection.

Abstract: A multisensor intrusion detection system having greatly improved immunity to false alarms is disclosed. This system employs a first sensor for sensing an intrusion in a volume of space by a first physical phenomenon and a second sensor for detecting an intrusion in the volume of space by a second physical phenomenon different from the first physical phenomenon. The first sensor generates a first signal in response to the detection of an intrusion into the volume of space, and the second sensor generates a second signal in response to a detection of an intrusion. A microcontroller generates an alarm signal upon the occurrence of one first signal and one second signal within a first interval, the occurrence of another first signal within a subsequent second interval and the occurrence of another second signal within a third subsequent interval.

Abstract: A dual sensing intrusion detection system has a microwave channel and a PIR channel. The signal from the microwave channel is amplified by an amplifier having a substantially constant gain, and is digitized and converted into a first digital signal. The signal from the PIR detector is amplified by amplifier having a substantial constant gain and is digitized and converted into a second digital signal. The first and second digital signals are compared to a microwave threshold signal and a PIR threshold signal respectively to generate an alarm signal. The system has a thermistor to detect the ambient temperature. The PIR threshold signal can be adjusted based upon changes in static conditions from the output of the thermistor. In addition, the microwave threshold signal can be changed statically based upon long term trend of the first digitized signal.

Abstract: An intrusion detector operating mode selection circuit sets an intrusion detector operating mode responsive to an encoded acoustic signal. An acoustic signal decoder receives an encoded acoustic signal and generates a mode selection signal in response thereto. The encoded acoustic signal is a plurality of spaced-apart acoustic pulses encoded by the relative inter-pulse timing of the spaced-apart pulses. A mode of the intrusion detector is set responsive to the mode selection signal.

Abstract: An intrusion detector test circuit automatically disables a detected-event indicator from receiving sensing signals. A sensor generates a sensing signal in response to a detection of an installer testing the intrusion detector. An indictor means receives the sensing signals and generates detected-event indications in response to the sensing signals. A switch interposed between the sensor and the indicator receives the sensing signals. In a first state, the switch supplies the sensing signals to the indicator; in a second state, the switch means does not supply the sensing signals to the indicator. A first state setter sets the switch to the first state, and a second state setter automatically sets the switch to the second state after a lapse of a predetermined time period.

Abstract: A dual technology intrusion detection device has a microwave detection sub-system, employing a bent mono-pole as an antenna to generate a symmetrical conically shaped volume of protection. The intrusion detection system also has a passive infrared intrusion detection sub-system, employing a hemispherically shaped fresnel lens having a plurality of lens segments, to detect infrared radiation from a plurality of spaced apart fields of view in a right symmetrical cone. The volume of protection for the infrared intrusion detector and microwave detector substantially coincide. In addition, the microwave detection sub-system employs a single bipolar transistor and a variable trim capacitor to generate the microwave energy and also uses the single bipolar transistor in an autodyne mode to mix the received microwave radiation.

Abstract: A multisensor intrusion detection system having greatly improved immunity to false alarms is disclosed. This system employs a first sensor for sensing an intrusion in a volume of space by a first physical phenomenon and a second sensor for detecting an intrusion in the volume of space by a second physical phenomenon different from the first physical phenomenon. The first sensor generates a first signal in response to the detection of an intrusion into the volume of space, and the second sensor generates a second signal in response to a detection of an intrusion. A microcontroller generates an alarm signal upon the occurrence of one first signal and one second signal within a first interval, the occurrence of another first signal within a subsequent second interval and the occurrence of another second signal within a third subsequent interval.

Abstract: An intrusion detection device of the dual sensing type has a PIR sensor to generate a PIR signal. The device also has a microwave sensor for generating a microwave amplitude signal. The microwave amplitude signal is filtered to generate a microwave high frequency signal which is the high frequency portion of the microwave amplitude signal. These three signals: PIR signal, microwave amplitude signal, and microwave high frequency signals are amplified and are digitized and are processed to generate an event signal. The event signal is compared to an event threshold signal and an alarm is generated in the event the event signal exceeds the event threshold signal. The event threshold signal represents the threshold to distinguish between a human intruder and an animal intruder.

Abstract: Dual microphones and a time-of-arrival processing circuit comprise a direction-sensing system which improves the false alarm immunity of an acoustic glass break detector by restricting its coverage to a well-defined zone. By comparing the arrival times of an abrupt sound at two spaced microphones, the processing circuit determines the direction of the sound. If the sound originated in the intended coverage zone, the processing circuit generates a signal which enables the glass break detector; otherwise, the detector is inhibited. When the improved glass break detector is oriented so that potential false alarm sources are outside the coverage zone, false alarm immunity is enhanced.

Abstract: A reed switch assembly and method of assembling it are disclosed. A preferred embodiment of the reed switch assembly includes an elongate hollow housing having an opening at one end thereof for access to a cavity therein. A reed switch is positioned completely inside the cavity. The first and second connecting leads of the reed switch are bent so that they are each substantially parallel to their respective first and second reeds and so that they lie in planes that are not coplanar with the flat portions of the first and second reeds. The first connecting lead has a length that is long enough so that it extends at least half-way over the reed switch body towards the second connecting lead. A first wire is attached to the first connecting lead at a connection point that is spaced apart from the free end of the first connecting lead a distance equal to at least one-half the total length of the first connecting lead.

Abstract: A battery container is of a size to accommodate two "AA" batteries situated side by side, or one "transistor" size battery. The container has two independent electrical contacts located at one end to make electrical contacts with the terminals of the "transistor" battery or with one of the ends of both "AA" size batteries. A retainer is located at another end of the container. The retainer provides electrical contact with the other ends of both "AA" size batteries. In addition, the retainer exerts pressure in the length direction to accommodate the smaller length of the "AA" or the "transistor" battery and exerts pressure in the width direction to accommodate the smaller width of the two "AA" or the "transistor" battery.

Abstract: A vehicle detector is disclosed wherein either a glass breakage signal or a door opening signal causes an alarm. The glass breakage signal is caused by the detection of high audio frequency simultaneously accompanied by the detection of a positive pressure change. The door opening signal is generated by the detection of a negative pressure change, which is not preceded by a positive pressure change.

Abstract: A segmented focusing mirror having a plurality of segments with each segment having a different focal length is made by constructing a plurality of mirrors with each mirror having a different focal length. The plurality of mirrors are sliced or are cut up into a plurality of segments. One or more segments of one mirror are combined with one or more segments of another mirror to form a master mirror. The master mirror has a common focal point with the segments having different focal lengths. A segmented focusing mirror is replicated from this master mirror by forming a mold of this master mirror and replicating therefrom.

Abstract: A microwave intrusion detection system having a transceiver positioned to one side of a substantially conductive member and an antenna positioned on the other side of the conductive member. The antenna shares the conductive member with the transceiver by utilizing the conductive member as a reflective surface. A transmission line is included which has a strip conductor positioned to the one side of the conductive member and a dielectric material therebetween. An antenna has a substantially planar conductive member, a strip conductor positioned to one side of the conductive member, and a dielectric material sandwiched therebetween. A length of wire lies in a plane which is positioned to a second side of the conductive member and is spaced apart a distance from the conductive member. A feed probe wire couples one end of the length of wire to the strip conductor and extends through the conductive member and through the dielectric material.

Abstract: A glass break simulator responds to a low-frequency sound component of the sound of breaking glass produced by striking the glass. The glass break simulator detects the low-frequency sound component and when an amplitude of the low-frequency sound component exceeds a predetermined threshold value, the simulator generates a high-frequency sound component by converting a digital representation of the high-frequency sound component into sound. The low-frequency sound component and the generated high-frequency sound component are directed at a glass break detector to test it, with the glass break detector responsive to both low and high-frequency sound components.

Abstract: A sensor has a reduced probability of generating a false alarm in the presence of a strong high frequency acoustic wave, such a false alarm being caused by the saturation of the microphone which is part of a single microphone glass break sensor. The sensor improves an alarm system's immunity to false alarms by using two microphones instead of one, wherein each microphone is used in combination with a filter and a signal processing stage to detect one of the characteristic components of an acoustic wave generated in a glass break event. The microphone used to detect the low frequency component is fitted with an acoustic filter which attenuates the high frequency component of the wave. This reduces the probability of a false alarm by ensuring that the low frequency electrical signals fed to the alarm system's logic and timing circuit are generated by an external event rather than by the microphone itself.

Abstract: A protective housing for enclosing a reed switch which includes an elongate hollow member having an opening at one end for access to a cavity inside the member. The cavity is sized to permit insertion of the reed switch inside the cavity. Fillant substantially closes the opening of the hollow member without making contact with the body of the reed switch. The fillant surrounds wires which are attached to the connecting leads of the reed switch. A method, which utilizes a blocking member, of enclosing a reed switch in a hollow member is also disclosed.