Abstract: A smoke detector is provided with testing apparatus for determining if its sensitivity is within a predetermined acceptable range. The testing apparatus stores in the detector a range representing acceptable sensitivities. When a test is initiated the resulting test output is compared to the sensitivity range, or its representation, and a warning signal is provided when the output is not acceptable. According to one feature, the stored representations of the acceptable range include a maximum acceptable value and a minimum acceptable value, and the warning signal indicates when the output is above the maximum or below the minimum. According to other features, the output signal is periodic at one frequency when above the maximum and at another frequency when below the minimum. The test is initiated by a magnetic reed switch and the results are immediately apparent.

Abstract: A security system having a communications link with a central control, including a local network responds: a) to central control when the central communications link is operational; and, b) to local control when the central communications link malfunctions. More specifically, the local network includes a plurality of receivers for detecting emergency communications, an alarm for issuing a perceptible warning and a local control. The local control notifies the central control when an emergency signal is detected and activates the alarm in response to direction from the central control. The local control also includes logic for directly activating the alarm when an emergency signal is detected and there is no response from central control. According to more specific features, the central control includes data for validating emergency signals and activates the alarm only after validation. The local control, on the other hand, activates the alarm without validation.

Abstract: A method and apparatus in a smoke detector for comparing an analog signal voltage to a digital alarm threshold and for converting a digital sensitivity value to an analog test voltage. The analog signal voltage is converted to a digital value by: a) charging a capacitor at a first linear rate directly proportional to the analog signal voltage, for a predetermined time period; b) discharging the capacitor at a second predetermined linear rate to a predetermined threshold; c) counting during the discharging of the capacitor to establish a digital count representing the signal voltage; and, d) comparing the digital count to a an alarm threshold stored in the detector prior to its installation. The digital sensitivity value is converted to the analog test voltage by: charging the capacitor from the first predetermined voltage, at a predetermined rate, for a time period based on the sensitivity and a calibrated conversion factor. This charges the capacitor to an analog voltage representing the sensitivity.

Abstract: A process and apparatus are provided for calibrating an individual smoke detector prior to installation so its sensitivity can be determined easily throughout its useful life. Representations of detector output signals are stored in the detector prior to installation, preferably at the time of manufacture, and used later for determining the sensitivity of the detector. The signals may represent alarm and clean-ambient conditions, or one of such conditions and the difference between them. During monitoring of the detector, after its installation, a new reading of a corresponding signal under clean-ambient conditions is sampled and the differences before and after installation are compared to determine the sensitivity of the detector when it is monitored. The detector includes electrical contacts from which a representation of detector sensitivity is available for monitoring with an external electrical probe, such as a common voltmeter.

Abstract: A security detector including an optical emitter and a controller for determining detector specific values of predetermined parameters and operating the emitter to transmit a code representing the values. The controller periodically initiates test cycles of the detector, determines the detector specific values, and operates the emitter to transmit a bit stream including an alpha-numeric code representing the values. For a smoke detector, the parameters include atmospheric density, information for determining detector sensitivity and alarm threshold. The emitted radiation is in the visible spectrum and the controller operates the emitter to transmit one code at rates perceptible to humans and another code imperceptible to humans. The imperceptible code provides machine readable information as bytes of alpha-numeric characters. Other features include a method and an optical reader for decoding and displaying the transmitted data.

Abstract: A passive infra-red, pet immune intruder detector includes upper and lower fields-of-view or zones. The detector is less sensitive to infra-red targets in the lower zones, compared to the upper zones, and the alarm threshold is set slightly above the level required to detect humans in the lower zones. Animals, which do not have access to the upper more sensitive zones are not detected in the lower relatively insensitive zones. The detector includes pyroelectric sensing elements and multi-faceted optics for directing infra-red energy onto the sensing elements from at least one lower zone, intercepting the floor plane, and at least one upper zone, extending entirely above the floor plane. The facet defining the lower zone focuses infra-red energy onto the sensing elements less efficiently than the facet defining the upper zone.

Abstract: A wearable transmitter assembly includes a housing containing a radio frequency transmitter and tamper detecting circuit that are attached to an appendage of an individual with a buckle and strap. A light emitter and a light sensor are disposed in the housing and extend to the outside of the housing through one or more apertures. The strap includes an embedded optical fiber. Attachment of the housing to the buckle positions the emitter and sensor adjacent the ends of the optical fiber in the strap to complete an optical path or circuit from the emitter around the appendage to the sensor. The housing is sealed closed, including sealant between the emitter, the sensor and the aperture, providing a water tight enclosure for said transmitter from the time of its manufacture. Attachment of the housing to the buckle completes a seal blocking contaminates, such as water, water vapor, and soap from the ends of the optical fiber, the emitter and the sensor.

Abstract: In a security system, a transmitter housing and first and second transmitter actuation elements cooperate to define thumb and finger saddles on opposite sides of the housing. The peripheral edge of the housing and the first and second actuation elements have matched configurations aligned at the thumb and finger saddles for guiding a hand to properly operate the transmitter while blocking other objects from accidental operation. The housing extends beyond the actuation elements at the ends of the elements while the actuation elements extend beyond the housing at the center of the elements. The housing has a first texture, such as a rigid plastic, while the actuation elements have a softer feel provided, for example, by an elastomeric material.

Abstract: A microwave intrusion detector is provided with a periodic signal detector that identifies periodic signals not typical of an intrusion and adjusts the alarm threshold in response such identification. The intrusion detector includes an adjustable threshold and a noise compensating circuit that actively adjusts the threshold at a first predetermined rate to mask background noise levels. The periodic signal detector modifies the adjustment, increasing the predetermined rate, when it detects a periodic signal typical of a motor, fan, florescent light or the like. The periodic signal detector also cancels or disables any pending or ongoing alarm to provide sufficient time for the threshold adjustments at the increased rate.

Abstract: A personal security system with system wide testing includes a portable transmitter that produces an emergency signal including a personal identification number and an auxiliary code. The auxiliary code may be a test bit which, when set, indicates that the emergency signal was activated in a test mode and that an emergency condition did not exist. Activation of the test mode is accomplished by the same systems required to activate the emergency signal to provide full testing. The transmitter is part of a security system including a plurality of portable transmitters and fixed receivers. The transceivers issue either an alarm activating signal or a test signal depending on the test bit in the auxiliary code. A successful test is discernible to the user from the vicinity of the transceiver.

Abstract: A personal security system including features for monitoring guard tours and other surveillance by security personnel. The security system includes a plurality of hand-portable transmitters, a plurality of fixed receivers and a control station. The transmitters are actuated to emit radio frequency signals including a class code that identifies first and second sets of the transmitters. The first set is assigned to security personnel and the second set to system subscribers. The receivers decode the signals from the transmitters and provide an output representing the receiver and the received class code. The control station identifies the location of the transmission using information from the receiver output, and records the time of the transmission. If the class code represents a security-assigned transmitter, the control station reports the information as a security function, such as a guard tour.

Abstract: A smoke detector is provided with testing apparatus for determining if its sensitivity is within a predetermined acceptable range. The testing apparatus stores in the detector a range representing acceptable sensitivities. When a test is initiated the resulting test output is compared to the sensitivity range, or its representation, and a warning signal is provided when the output is not acceptable. According to one feature, the stored representations of the acceptable range include a maximum acceptable value and a minimum acceptable value, and the warning signal indicates when the output is above the maximum or below the minimum. According to other features, the output signal is periodic at one frequency when above the maximum and at another frequency when below the minimum. The test is initiated by a magnetic reed switch and the results are immediately apparent.

Abstract: Apparatus and a method for detecting glass breaking from an impact. Low frequencies are detected that are characteristics of the glass flexing from the impact, and high frequencies are detected that are characteristic of a) the sound of the impact and b) the glass breaking. An alarm signal is issued when the low and high frequencies occur in a predetermined sequence, and have appropriate durations, that are characteristic of glass breaking events. More specifically, the alarm sounds only when low frequencies are detected not before the high frequencies are first detected but within a predetermined time period after the first detection of the high frequencies.

Abstract: A process and apparatus are provided for calibrating an individual smoke detector prior to installation so its sensitivity can be determined easily throughout its useful life. Representations of detector output signals are stored in the detector prior to installation, preferably at the time of manufacture, and used later for determining the sensitivity of the detector. The signals may represent alarm and clean-ambient conditions, or one of such conditions and the difference between them. During monitoring of the detector, after its installation, a new reading of a corresponding signal under clean-ambient conditions is sampled and the differences before and after installation are compared to determine the sensitivity of the detector when it is monitored. The detector includes electrical contacts from which a representation of detector sensitivity is available for monitoring with an external electrical probe, such as a common voltmeter.

Abstract: A transmitter assembly is characterized by a buckle including fasteners for holding a strap and the buckle together on an appendage of an individual independent of a transmitter. The buckle also includes latches for attaching the transmitter to the buckle after the buckle is strapped to the individual. An optical fiber running through the strap is held by the fasteners with the ends of the fiber in predetermined positions relative to the buckle. The transmitter covers the strap fasteners, rendering the fasteners inaccessible to the individual, and aligns an emitter and sensor on the transmitter housing with the ends of the optical fiber in the predetermined positions. The ends of the strap are aligned adjacent one another by the buckle, so the buckle adds little to the length of the strap, permitting length measurements without considering the buckle contribution.

Abstract: A personal security system includes a test feature for end-to-end testing. A portable transmitter produces an emergency signal including a personal identification number and an auxiliary code. The auxiliary code may be a test bit which, when set, indicates that the emergency signal was activated in a test mode and that an emergency condition did not exist. Activation of the test mode is accomplished by the same systems required to activate the emergency signal to provide full testing. The transmitter is part of a security system including a plurality of portable transmitters and fixed receivers. The transceivers issue either an alarm activating signal or a test signal depending on the test bit in the auxiliary code. A successful test is discernible to the user from the vicinity of the transceiver.

Abstract: A portable transmitter produces an emergency signal including a personal identification number and an auxiliary code. The auxiliary code may be a test bit which, when set, indicates that the emergency signal was activated in a test mode and that an emergency condition did not exist. Activation of the test mode is accomplished by the same systems required to activate the emergency signal to provide full testing. The transmitter is part of a security system including a plurality of portable transmitters and fixed receivers. The transceivers issue either an alarm activating signal or a test signal depending on the test bit in the auxiliary code. A successful test is discernible to the user from the vicinity of the transceiver.

Abstract: An intrusion detection system, including a microwave device and a light emitting diode, is controlled to alternate their operation so the diode is off and not conducting when the microwave is transmitting. During a period when the LED would otherwise be on to indicate some state of detection, it is cycled off to remove its influence from the microwave transmission and reception. The microwave transmissions are intermittent with relatively long intervals between short transmissions. The diode is switched on during the long interval and off during the transmissions, giving the appearance of a diode that it is always on. The invention has particular utility in apparatus including dual independent channels for detecting intrusion and including one or more light emitting diodes that are energized to indicate the state of one or both channels.

Abstract: Apparatus and a method for detecting glass breaking from an impact. Low frequencies are detected that are characteristics of the glass flexing from the impact, and high frequencies are detected that are characteristic of a) the sound of the impact and b) the glass breaking. An alarm signal is issued when the low and high frequencies occur in a predetermined sequence, and have appropriate durations, that are characteristic of glass breaking events. More specifically, the alarm signal is issued only when the detected low frequencies last for a minimum duration on a sliding scale related to their magnitude. Weaker signals must last longer.