Abstract: An alarm system includes two subsystems: a security subsystem that performs critical alarm condition monitoring and reporting; and an auxiliary subsystem that allows execution of other non-critical software components. The security subsystem may monitor the performance of the auxiliary subsystem, and maintain the performance by resetting and/or otherwise controlling the execution of software and use of hardware at the auxiliary subsystem, providing increased overall reliability of the security system, without compromising its ability to monitor security conditions at an associated premises.

Abstract: An interface circuit configurable in input and output modes comprises a current source; an input/output node; a diode to prevent current from flowing from the input/output node to the current source; a first switch to short-circuit the diode when closed; and a second switch to form a ground path from the input/output node when closed. In input mode, the first switch is closed and the state of a connected sensor circuit may be measured. In the output mode, the first switch is open, and the second switch may be closed to activate an output circuit. In the output mode, power dissipation may be monitored, and the diode may protect the current source and measurement node from current flowing through the output circuit. In the input mode, closing the first switch may prevent the diode from introducing measurement errors due to non-linear attenuation of perturbative AC signals.

Abstract: A cabinet formed of a plurality of panels, includes a tamper detection system that includes an electrical circuit for detecting forming of a hole in a protected region of at least one panels. The electrical circuit includes at least one conductive trace on one of the panels. The conductive trace spans a protected region, wherein the minimum distance from any point in the protected region to the at least one conductive trace does not exceed some defined maximum. An electrical current source provides a current through the conductive trace. A sensor is in electrical communication with the electrical current source to sense a change in current provided to the trace and generate a tamper signal in response thereto.

Abstract: A load limiting circuit includes a transistor switch, for providing current to a load and a latching circuit having a control input, and a latch output driving the transistor switch. A current sensing transistor interconnects with the transistor switch, to sense current in excess of a threshold to the load. The current sensing transistor drives the control input to the latching circuit. An external controller may drive and monitor the control input. The controller may thus turn the transistor switch on and off, and be notified of an over-current condition. The latching circuit may turn the transistor switch off permanently. As well, the controller may attempt to set the load limiting circuit after an over-current condition.

Abstract: A bi-directional current limiter may be configured to receive an AC signal and bi-directionally limit the loop current to a predetermined current value. A first and second zone may be configured in series with the AC signal and bi-directional current limiter. The first and second zone may include unidirectional current limiters to limit a unidirectional current that is proportionately less than the bi-directionally limited current. A first opto-coupler circuit (ISO1) may be configured to detect both high and low current states in the current loop circuit. Second and third opto-coupler circuits (ISO2 and ISO3) associated with the first and second zones may be configured to detect only high current states in the current loop circuit. The status of the first and second zones may then be determined by an analysis of the current level in the current loop circuit during two half cycles as determined by the various current limiters.

Abstract: A voltage measuring circuit includes a rectifier to receive an alternating current (AC) voltage to be measured and to provide a rectified output; a comparator for comparing the rectified output and producing therefrom a square wave having a pulse width indicative of the rectified output exceeding a threshold; a calculation circuit for converting a measurement of the pulse width into a measurement of the voltage and optionally an opto-isolator interconnecting the comparator to the calculation circuit. The rectifier may provide operating power to the comparator and an input side of the opto-isolator, from the AC voltage signal being measured. The remainder of the measuring circuit may powered by a source isolated from the voltage to be measured.

Abstract: An AC measurement circuit includes a rectifier for receiving an AC signal; a peak detection circuit; and a voltage divider, interconnected with an output of the rectifier, and the input of the peak detection circuit to provide the peak detection circuit with a voltage value equal to a fraction of the AC signal. An analog to digital converter, has its analog input interconnected with an output of the peak detection circuit, for providing a digital output corresponding to its analog input. A summing circuit sums n samples of the digital output. The voltage divider is configured so that the summing circuit calculates an average measurement of the AC signal by summing n samples and without floating point division.

Abstract: A displacement sensor for sensing displacement of a first surface relative to a second surface includes a coil mounted on the first surface, and encircling a region in plane; and a conductor extending lengthwise from the second surface through the region. The conductor has a volume that varies along its length. An AC source drives the coil to generate a magnetic field that pierces the region and induces eddy currents in the conductor. Eddy current losses resulting from the eddy currents vary in dependence on the volume of the conductor above and beneath the plane. A sensing circuit is coupled to the AC source to detect changes in eddy current losses, and thereby displacement. Detection of displacement may be used to signal tamper/intrusion. The sensor may further include a visual or audible output to signal such displacement.

Abstract: The embodiments disclose a circuit for detecting and determining a type of ground fault in a security system. An operational amplifier (OA) having positive and negative inputs and an output may receive AC input signals having different frequencies, f1 and f2 at a positive input and provide an AC output signal at the output. An OA feedback loop may comprise a ground fault equivalent impedance connected at the OA negative input and a feedback resistor connected between the OA output and the OA negative input. A rectifier may convert the AC output signal to a DC signal and a filter to obtain a steady DC voltage from the rectified DC signal. A steady DC voltage for two different AC input signals may be obtained and converted to a relative voltage with respect to a constant input voltage amplitude. The relative voltages may be compared to detect and determine a type of ground fault condition.

Abstract: A battery test circuit for testing batteries in a working circuit having a plurality of batteries includes a DC step up converter. The DC step up converter may be selectively interconnected between a first one of a plurality of batteries and a second one of a plurality of batteries, to draw a test current from the first battery and to supply current at an elevated voltage to the second battery. The test circuit further includes an indicator output for providing a signal indicative of whether the first battery provides the test current substantially at its rated voltage.

Abstract: An alarm monitoring station is capable of establishing a two way communications channel over a network to connect the monitoring station and alarm panels at monitored premises, for real time voice communication between the panels and the monitoring station. The monitoring station is further operable to provide pre-programmed voice messages to the alarm panels based on the sensed alarm condition over the two way communications channel. In this way, occupants at the premises may be notified of the sensed condition before speaking with an operator at the monitoring station.

Abstract: An alarm system senses alarm conditions on a premises, reports the occurrence of an alarm condition to a remote monitoring facility and for selected alarm conditions establishes two way voice communications with a person at the monitored premises or elsewhere. Multiple modes of communication are available such as public switched telephone (audio or audio modulated data), GSM (cellular audio), GPRS (cellular packet data), GSM/SMS (cellular text), etc. The programmed processor selects the network and communication protocol to rely on data communications if only data reporting is required. When two way voice communications will be required, the processor can select a network (e.g., GSM) that can be used for both data and audio communications.

Abstract: A system and method are disclosed for enrolling two-way wireless security system devices (alarms, detectors, lights) in a security system. A controller is provided and is capable of exchanging wireless signals with the two-way wireless devices. The system has an enroll mode where the two-way wireless devices transmit enroll signals to the controller. The enroll signals contain an identifier associated with each device. An installer uses a keypad or other interface device to confirm enrollment of each of the devices. The controller sends an enroll confirmation signal back to the two-way wireless devices confirming that the devices have been enrolled. In response, each of the devices emits an audible or visual enroll confirmation signal to the installer.

Abstract: A security system including a main control unit, a plurality of sensors and a user interface device. The main control unit communicates with a remote central monitoring station when a sensor detects an alarm event. Once the communication signal from the main control unit is successfully transmitted to the central station, a siren is sounded. Thus, the delay time to trigger the siren is dynamic based on the time it takes for successful transmission of an alarm notification to the central station. This dynamic delay accounts for transmission interruptions between the security system and the central station and allows the location of the main unit and/or the siren from being detected prior to successful alarm transmission to the central station.

Abstract: A system and method are disclosed for using a single key to authenticate a user with respect to multiple user access points and to allow a single access point to authenticate multiple keys having different physical characteristics. The system may comprise an access control system that includes an insertion receptacle for receiving a physical key, and a translation device for observing the physical characteristics of the key and translating those characteristics into electrical signals. In a learning mode, the electrical signals are transmitted to a processor and stored in memory. In a verification mode, the electrical signals are transmitted to the processor and compared with the previously-stored signals. If the processor concludes that the signals match the signals stored in memory, then the processor instructs a lock actuation mechanism to actuate an access control device to allow the user access to a location.

Abstract: A system and method are provided for extending the expiration of an entry delay period for disarming a security system based on the entry of a keypress that matches a valid access code before expiration of a preprogrammed entry delay period. The security system includes a plurality of detection devices to detect any number of conditions, a user interface such as a keypad, and a control panel communicating with each of the detection devices and the user interface. The system extends the entry delay period based on the input of each keypress using the user interface that matches a symbol of a valid access code.

Abstract: An alarm system includes one or more audio stations, and an audio station network interface. The audio stations communicate wirelessly with the audio station network interface. The audio station network interface communicates with a monitoring center over a cellular network, to allow audio monitoring of the premises at the audio stations. The audio station network interface may be called by the monitoring center. Calls may optionally be placed by it in response to user interaction with one of the audio stations.

Abstract: A system and method are disclosed for recording and evaluating faults in event transmissions between security system components. A panel in a monitored building may send event signals to a receiver located in a central monitoring facility. Event signals may represent a status of individual alarms or sensors in the building, or they may provide a status of the system as a whole. If the quality of the transmission is substandard or in a format that is unacceptable to the receiver, the signal data associated with the event is recorded for analysis. Recording is controlled by a line card associated with the receiver, and the signal data is stored in local or remote memory. Signal data can be manually or automatically analyzed to determine the source of the fault. In addition, recorded signal data can be used to build customized software to recognize signals from previously unrecognized or faulty panels.

Abstract: A method and security system arrangement are disclosed for processing incoming signals at an alarm monitoring station. The method includes analyzing the incoming signals to assess if any particular incoming signal includes characteristics of a facsimile signal to thereby identify whether or not a given incoming signal is a facsimile signal. If the analyzing identifies that a given incoming signal includes characteristics of a facsimile signal, thus identifying that the given incoming signal is likely a facsimile signal, the alarm monitoring station refrains from initiating an alarm handling procedure to handle the given incoming signal. Caller ID information may be extracted from the facsimile signals received by the alarm monitoring station, and added to a call block list. Calls originating from caller IDs on the call block list may be blocked by the alarm monitoring station.

Abstract: In an alarm system, outgoing calls representing a sensed alarm condition are routed to one of several communications networks. The calls are routed by first initiating a telephone call to a defined number, in response to sensing the alarm condition, and then selecting one of plurality a plurality of available networks based on called number information. A communication over the chosen network is placed to signal the alarm condition. Routing may be performed at an interface module in communication with a conventional alarm panel.