Abstract: A method and system for detecting a vehicle roll-over utilizes a z-axis accelerometer (12) and a processor (20) for analyzing the accelerometer output (18) to provide early detection/prediction of a vehicle roll-over. The output signal (18) is substantially a positive constant value equal to the force of gravity when the vehicle (16) is in a normal upright condition, and as the vehicle (16) experiences a roll-over, the output signal transitions to a substantially negative constant value when the vehicle has rolled 180.degree. upside down. To provide early roll-over detection and/or prediction, the z-axis data is averaged (102) and compared to a first threshold value (104) set to a g-force value within a range of 0 to -1 g. Estimating a slope value (step 110), i.e. the change in z-axis data over time, can provide an additional discrimination measure to improve overall reliability, and to provide a qualitative measure of the roll over.

Abstract: A method of supervising the operation of an intrusion detector having a housing, the method including periodically generating in the housing at least one sound wave signal, sensing an acoustic image formed in the housing in response to the at least one sound wave signal, constructing a sensed signal envelope responsive to the sensed acoustic image, periodically comparing the sensed signal envelope with a reference signal envelope to determine whether a predetermined criterion of similarity between the sensed signal envelope and the reference signal envelope is met and, if the similarity criterion is not met, providing a predetermined, sensible, indication.

Abstract: The invention is directed to a switch arrangement for signaling the movement and the inclination of the switch arrangement which is accommodated in a housing. The switch arrangement (2) includes a first switch (12) configured as an On/Off switch and a second switch (10) connected to a capacitor (K). The switches include each conductor portions (22, 24) adapted to be connected to each other by a movable actuating member (18). While the switch (12) signals both the movement and the inclination of the arrangement (2), the switch (10) signals a movement of the arrangement (2) by issuing pulse signals. In the position of the rest of the actuating member (18), none of the switches is activated. In one configuration of the switch arrangement, the actuating member is guided in a cutout whose sides extend towards each other in a converging fashion.

Abstract: A beeper controlled auto security system in which a vehicle disabling device such as an ignition kill switch is selectively activated either by a hand held rf transmitter unit or a beeper paging system satellite transmission initiated by a telephone call which may be at a very remote location from the vehicle. A vehicle motion detector is also activated which turns on a monitor transmitter if the vehicle is thereafter moved, enabling detection by a portable monitor receiver carried by the vehicle owner or police vehicles.

Abstract: A vehicle interior is monitored by storage of sample signals in a memory of a computer and comparison of at least one stored sample signal with a signal picked up on a detector of sound waves from the interior of the vehicle. An identity or similarity test is conducted by the computer and an alarm device is triggered when the predetermined degree of similarity is reached to signal an incursion.

Abstract: A shock detector for measuring intermittent shock events comprises a mechanical delay line to supply delayed output motion in response to input motion along an input axis. A transducer converts the delayed output motion to an electrical signal representative of the delayed output motion. The transducer is generally in a respective inactive state to reduce the power consumption of the shock detector. A relatively low power motion sensor, such as low power accelerometer or tilt actuated switch, is employed for switching the transducer to a respective active state in response to the input motion thereby allowing the shock detector to measure any intermittent shock event regardless of the generally inactive state of the transducer.

Abstract: A seismic alarm device for vehicles which is capable of detecting an earthquake while the vehicle is moving and gives the alarm upon occurrence of the earthquake in order to provide the safety such as by stopping the motor vehicle, wherein a plurality of acceleration detectors are mounted on the front and rear of the vehicle or on the left and right sides of the vehicle, output signals generated from these acceleration detectors are fed to a determination circuit, which determination circuit is arranged to measure an amplitude and period of the output signals and to compare phases of the output signals, then to output an alarm signal if the amplitude of the output signals is larger than a predetermined value while their periods are within a predetermined range and no phase difference exists between the output signals of the acceleration detectors, and an alarm circuit gives the alarm when the determination circuit outputs the alarm signal.

Abstract: An alarm system for detecting unauthorized removal of a wheel assembly or wheel accessory from the vehicle includes a sensor having a secured state and an unsecured state. The sensor is in the secured state when the wheel assembly or accessory is installed on the vehicle and in the unsecured state when it is removed from the vehicle. An alarm transmitter is connected to the sensor and alters a radio frequency (RF) alarm signal when the sensor changes from the secured state to the unsecured state. A receiver, located remotely from the alarm transmitter, receives the RF alarm signal and generates an alarm triggering signal in response thereto. The sensor and alarm transmitter are preferably part of a sensing assembly which includes a fastener for connecting the sensing assembly to a wheel lug or other wheel part. The sensing assembly includes a housing with a cavity for enclosing the sensor and the alarm transmitter. The sensor may be a pressure switch, an electronic switch or other sensing device.

Abstract: A method of indicating the threat level of an incoming shock to an electronically secured vehicle and eliminating spurious signals developed from the interaction of EMF and RF energy fields with the shock sensor including the steps of sensing a shock delivered to the vehicle indicative of an attempted intrusion, generating an electric signal the strength of which is proportional to the intensity of the shock, analyzing the signal to determine if it is of a low, generally non-threatening intensity or a higher, generally security-threatening intensity, ignoring the first 5 milliseconds of the signal produced by the shock sensor, ignoring all signals that do not disappear and later reappear, and producing either a first pulse representing a low intensity signal, or separate first and second pulses representing a signal containing both low intensity and higher intensity components.

Abstract: A protective device for storage and transport containers comprises a sensor for detecting orientation, an attachment element for securing the sensor to a container, and an alarm operatively coupled to the sensor for generating a cognizable alert signal upon detection by the sensor that the container is in an orientation other than a predetermined preferred orientation. The alarm may include an electroacoustic transducer and means for reproducing a voice message. A timer operatively connected to the sensor measures a time interval during which the container is in an orientation other than the preferred orientation. A memory is operatively connected to the timer for automatically storing the time interval in encoded form. A mechanism and/or circuit may be operatively connected to the timer and the memory for deactivating the timer and for locking the memory to ensure integrity of contents of the memory upon an opening of the container. The device may also include a detector for measuring temperature.

Abstract: A security device, intended for use as a temporary or permanent vehicle security device, having an intrusion detection device in the form of a pair of electrical contacts supported on a shock amplifying, rigid base and responsive to percussive-type forces for generating a detection signal. At least one of the electrical contacts is supported on a relatively stiff cantilevered arm which will not respond to small movements and vibrations, to thereby avoid generating frequent false alarms. Any contact closure signal from the electrical contacts is processed by a detection circuit which counts multiple contact closures and/or measures total closure time, thus ignoring signals generated from small forces or vibrations, thereby preventing against the source of most false alarms when generating a detection signal.

Abstract: Sound, vibration and motion are sensed within a motor vehicle to detect glass breakage and unauthorized intrusion into the interior or passenger compartment of the vehicle. Sound and vibration sensing are used to detect glass breakage with motion detection by means of radar or microwaves being utilized for intrusion detection to provide reliable recurring entry detection. The system may be operated to activate the motion sensing only after glass breakage is detected to permit persons and pets to occupy a motor vehicle having a security sensor system which is fully armed. Numerical values are assigned to specific physical sounds and vibrations with the resulting totals being compared to a threshold to determine whether glass breakage has occurred.

Abstract: The present invention relates to a device for shutting off an engine remotely and sounding off an alarm locally and which includes an alarm motor, a module for activating the alarm motor, a key switch for turning the module on and off, a siren connected to the alarm motor, and a battery with an alternator terminal.

Abstract: A shock sensor includes a mass suspended in a flexible support arranged to resonate when subjected to a mechanical shock, a microphone spaced closely to the mass, the mass and microphone forming a first air pressure chamber with the flexible support for transmittal therethrough of air pressure waves from the resonating mass to the microphone, the microphone arranged to produce an electronic signal when it detects changes in air pressure from the pressure waves traveling through the chamber.

Abstract: A method and apparatus for preventing automobile theft which includes structure for rendering the front windshield, or all the windows of the automobile, opaque. The opaqueness may be caused either by mechanical means, or alternatively, by utilizing liquid crystals or similar media, energized by electric fields.

Abstract: A shock sensor includes an inductance coil, a magnet, a magnetically soft material, and a support bracket for the magnetically soft material. The inductance coil and the magnet are fixed relative to each other. The magnetically soft material has one side thereof fixed on the support bracket and lies relative to the coil and the magnet so that the magnetically soft material can move up and down as well as leftwardly and rightwardly and inwardly and outwardly when the shock device vibrates and thereby alter a magnetic flux from the magnet to the inductance coil so as to generate signals responsive to the fluctuations of a magnetic flux.

Abstract: Transducer apparatus (10) responsive to external perturbations is disclosed having an electrically responsive transducer circuit (12) energized when a display member (18) and an elongate member (20) move from a gravity determined quiescent orientation (30A) therebetween to an external perturbation driven activate orientation (30B) therebetween. In various embodiments, the members are respectively responsive to air movement and acceleration. In one embodiment, the elongate member carries a first electrical contact (21) to abut a second electrical contact (22) carried by the display member.

Abstract: A motion sensor for use with a security system provides an output signal to initiate an alarm whenever a significant level of movement is detected by the motion sensor. A light emitter directs light through an optical path onto a light detector, which generates an electrical output signal in response to the light directed onto it. A resiliently supported mass is coupled to the optical path to modify the optical path in response to motion imposed upon the mass, thereby reducing the transmission of light in the optical path and affecting the electrical signal as the mass moves. The motion sensor of the present invention is responsive to movement in all directions, and, since it is optical in nature, is immune to the presence of magnetic fields.

Abstract: A vehicle anti-theft device and alarm includes a U-shaped rod for attachment to a vehicle steering wheel in a position overlying the vehicle dash board. An alarm is positioned in said U-shaped rod, whereby said alarm is firmly secured to a vehicle and inaccessible for tampering.

Abstract: Transducer apparatus (10) responsive to external perturbations is disclosed having an electrically responsive transducer circuit (12) energized when a display member (18) and an elongate member (20) move from a gravity determined quiescent orientation (30A) therebetween to an external perturbation driven activate orientation (30B therebetween. In various embodiments, the members are respectively responsive to air movement and acceleration. In one embodiment, the elongate member carries a first electrical contact (21) to abut a second electrical contact (22) carried by the display member.

Abstract: A portable automobile alarm hung over the top of an automobile side window is secured in place by raising the window into its frame. The portion of the unit positioned on the interior side of the glass contains a sensor, a receiver, and associated electronic circuitry. The exterior unit houses an alarm siren. The unit is powered from an internal battery or from a cigarette lighter. The unit may be armed and disarmed by a remote transmitter.

Abstract: An electronic alarm system using graphite sensor will be activated when the sensor is either cut, shorted, or touched. A rapid change of the sensor signal will be detected by a differential section when the sensor is touched, but not a slowly drifting sensor signal when the sensor is not touched. A comparing section takes positive or negative signal to activate the alarm system by sending a signal to a output section.

Abstract: An aftermarket mechanical shock detector for mounting to protected property containing an existing alarm system. The shock detector incorporates a piezoelectric transducer detecting mechanical vibration and generating an electrical vibration signal, and circuitry for comparing the vibration signal to thresholds. The shock detector includes two separately adjustable thresholds. If the vibration signal exceeds either threshold, the shock detector creates an electrical connection between two terminals, thereby triggering a previously-installed alarm circuit to create an alarm.

Abstract: An alarm system is disclosed which includes a triggering device which triggers a warning device in the case of an unauthorized change of the position of the motor vehicle. The device comprises a compass by means of which the actual position value is reported to a control apparatus. As soon as the compass reports a value to the control apparatus which deviates from the stored position value, the warning device is activated.

Abstract: A car-used burglarproof device capable of emitting human voice, including a remote transmitter, a central door lock controller, a wireless SOS system, a remote receiver, a decoder, a latch circuit, a vibration detecting circuit, a counter, a timer, a voice system and a re-triggerable timer, whereby the remote transmitter is operated to transmit signal to the receiver and the receiver responds to the signal by voice or sound. When the burglarproof effect is set up or released, the car doors are simultaneously locked or unlocked. After the burglarproof effect is set up, if the car is touched or shocked, the burglarproof device will emit a voice of "this car is equipped with alarm system, please don't touch". If the car is again touched, the burglarproof device will emit a warning voice of "if you touch the car again, I shall call the police".

Abstract: A motor vehicle having an engine and drive train is protected by a security system including a sensor, a sequencer and an interrupter. The sensor can detect motion of the motor vehicle to provide a motion signal. The sequencer is coupled to the sensor and responds to the motion signal for providing a disable signal after production of the motion signal. The interrupter is coupled to the engine for disabling it in response to the disable signal. Thus the motor vehicle is disabled only after its motion is detected.

Abstract: A self-contained portable interface system (10) coordinates vehicle light response on separate vehicles. A power interface (13) plugs into a cigarette lighter (14) on the first vehicle (16). A turn signal detector (18) releasably engages a turn signal lever arm (22) on the first vehicle (16) for the purpose of detecting actuation of turn signal lights on the first vehicle (16). A flasher switch (25) is disposed on the turn signal detector (18) for concurrently actuating turn signal lights on the second vehicle (12). A control unit (24) communicates via a ribbon cable (42) to the power interface (13) and the turn signal detector (18). The control unit (24) has a light sensing switch (28), which is actuated by atmospheric light, for switching park lights of the second vehicle (12) during the absence of light. An inertia sensor (56) detects deceleration of the first vehicle (16) and causes actuation of brake lights of the second vehicle (12) in response to the deceleration.

Abstract: A beeper controlled auto security system in which a vehicle disabling device such as an ignition kill switch is selectively activated either by a hand held rf transmitter unit or a beeper paging system satellite transmission initiated by a telephone call which may be at a very remote location from the vehicle. A vehicle motion detector is also activated which turns on a monitor transmitter if the vehicle is thereafter moved, enabling detection by a portable monitor receiver carried by the vehicle owner or police vehicles.

Abstract: A motion detector having a motion sensitive switch, timing circuit, encoder and radio-transmitting circuit in a housing which may be affixed to a remotely-positioned article; and a decoding and receiving circuit housed in a second housing. The radio-receiving circuit receives the encoded transmitted signal and couples it to a decoding circuit; the decoding circuit is connected to a latch circuit which drives an alarm. The sensitivity of the alarm generation circuits are controlled by a timing circuit, and the alarm may be disabled in order to enable the operator to evaluate the nature of the incoming signals.

Abstract: An anti-theft device with a sound warning device for attachment to the steering wheel of an automobile comprising a sound warning device deposited in an inner cavity in an elongate rod of the steering lock, the sound warning device consisting of a case, an electronic circuit board contained in the case and having electronic components to send out a signal to a sound system of the automobile to give out a warning sound in case the body or the steering wheel should be touched by a would-be burglar, and a cover closing on the case in the cavity in the rod.

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 device for marking motor vehicles in order to assist law enforcement officers in identifying and apprehending a motor vehicle that has illegally fled after being stopped. The vehicle marking device comprises plastic pouches or sacs containing dye, and explosive cartridges such as model rocket propellant for rupturing the pouches and expelling the dye onto an exterior surface of a motor vehicle. An electronic control for firing the explosive cartridges includes a master switch for arming and disarming the marking device, an inertia switch for detecting motion of the motor vehicle, and a timer for delaying firing of the explosive cartridges for a predetermined period of time after the inertia switch detects motion.

Abstract: An anti-theft device for attachment to a steering wheel of a vehicle and comprising telescoping components relatively displaceable between extended and retracted positions respectively corresponding to use and storage positions for the device is provided with an electric circuit which is activated in the stored position of the device and issues an audible signal to remind the operator of the vehicle to attach the device to the vehicle steering wheel when the operator leaves the vehicle. The electric circuit includes a vibration sensor for sensing vibration of the device such as when the vehicle motor is running or the vehicle is moving along a roadway. When the vehicle is parked and the motor turned off, whereby there is no vibration of the device, an audible signal is issued, such as a digitized voice message for example, to remind the operator to install the device before leaving the vehicle.

Abstract: A car security system has a proximity sensor such as a radar sensor with variable sensitivity and capable of producing a detection signal upon detecting motion of a person in a monitoring area. A control circuit is provided controls the sensitivity of said proximity sensor. The system also has a monitoring/alarming control circuit for control of predetermined monitoring and alarming control on the basis of the output from the proximity sensor, and alarming devices such as a headlight flash circuit, buzzer and siren for performing a predetermined alarming operation under the control of the monitoring/alarming control circuit. The sensitivity control circuit operates in response to a predetermined operation such as an arming start operation to vary the sensitivity of the proximity sensor so as to automatically set the sensitivity to a first sensitivity level which is the highest level within a range which does not cause the sensor to produce the detection output.

Abstract: A vibration sensor is secured to an object whose vibrations are to be sensed, and includes a vibration plate capable of resonating at one of first resonance frequencies within a specific high frequency region of the frequencies at which the object can vibrate. A vibration element capable of resonating at one of second resonance frequencies within a specific low frequency region of the frequencies at which the object can vibrate is connected to the vibration plate so that the vibration resulting from the resonance of the vibration element is transmitted to the vibration plate. Further, a piezoelectric transducer element is fixed to the vibration plate, and is able to generate an electric signal in response to the stress applied by the vibration plate when this plate vibrates. Thus, it is possible, with a single sensor, to sense both vibrations composed of relatively high frequency components and vibrations composed of relatively low frequency components.

Abstract: An alarm system senses the presence of a person sufficiently near a protected object, such as an automobile, to inflict damage thereto, and provides verbal warnings to the person. The alarm system includes a proximity detector that senses the proximity of a person to the protected object and means for generating vocal signals using electronic speech generation circuits. Such vocal signals typically instruct the person to back away from the protected object, thereby preventing the person from inflicting any damage to the object. The user may select various operating modes and performance options in how the system is used.

Abstract: A vehicle security system including a key switch, a first relay, a second relay, a first timer, a second timer, a warning device, and a push-button switch. The key switch activates and deactivates the system. Once the key switch is in an operative position and the system is activated, the vehicle's ignition switch in an operative position activates the second relay. Operation of the second relay, or of a vehicle door switch, activates the first relay which starts the first and second timers. The first timer initiates a first timing delay and, at the end of this timing delay, activates the warning device. The warning device warns the driver that the alarm sequence has been initiated. The push-button switch initiates an engine standby mode. The second timer initiates a second timing delay and cuts off the engine unless a standby mode is initiated before the end of the second timing delay.

Abstract: An automobile theft sensor has a piezo-electric element adhered at one side to a base member and which generates a voltage in response to vibration of the automobile body, a weight adhered to the opposite side of the piezo-electric element, a silicon rubber coating covering at least a portion of the surface of the piezo-electric element and weight, a low pass filter for receiving the output voltage of the piezo-electric element and for providing an ultra low frequency signal within the range of 1-5 Hz produced by the above mentioned piezo-electric element; and a band pass filter for receiving the output voltage of the piezo-electric element and for providing a low frequency bandpass signal centered on the 30-50 Hz produced by the above mentioned piezo-electric element in response to vibration of the above mentioned automobile body. When either of the filter outputs exceeds a predetermined level it is judged that theft or tampering is occurring.

Abstract: A vehicle collision detecting apparatus includes an acceleration sensor detecting acceleration of a motorcar, a frequency filter extracting a signal in a predetermined frequency band from the acceleration signal, and a detector for detecting a collision in accordance with the extracted signal. The detector supplies a trigger pulse to an airbag driver circuit.

Abstract: A security device includes a portable transmission unit that gives an instruction to start or stop security, a sensor that detects an abnormality of a tuner which receives a signal from the transmission unit and of an automobile, a sensor circuit having predetermined characteristics for discriminating the output of the sensor, and a security control section for causing a theft prevention device like a siren to be activated after output from the sensor circuit is received, wherein the characteristics of the sensor circuit can be set by the transmission unit.

Abstract: A bar code scanner which is responsive to the movement of the scanner to activate its light source. The scanner includes a motor having a moving member which is set in motion when the scanner is displaced from a rest position. The moving member generates a voltage in a coil, which activates the operation of the bar code scanner.

Abstract: A shock and vibration detecting device comprising a sensor enclosed in an electromagnetic shielded and dust-proof case to send out a signal to an amplifying circuit constituted mainly by an operational amplifier once it picks up a shock and/or vibration signal. The output of the amplifying circuit is connected to a driving circuit to provide an output signal. A delaying circuit is used to lengthen the active period of the output signal. A voltage regulation circuit provides a regulated and filtered voltage to the above-mentioned circuits.

Abstract: An electronic audible warning device (10), which includes a power source (18), a motion detector (401), a pleasant tone generator (100, Q1, Q3), a loud piercing tone generator (100, Q1, Q2) and a remote push button activation switch (19) is disclosed. Signaling device (10) provides two distinct features, each responsive to remote activation switch (19). A single depression on push button switch (19) will sound an unobtrusive, pleasant sounding two second pulsating warning tone. Two consecutive pushes on push button (19) will sound an attention-getting pulsating signal, similar to the backup beeper on commercial trucks, which will continue to sound until button (19) is pressed again. An additional feature is provided which is responsive to a motion detector (401). Here, a loud, piercing tone is sounded whenever a bicycle (1) or similarly attached article is moved. The alarm is activated and deactivated via an electrical key switch (402) which is installed directly in main housing (11).

Abstract: A lock structure arranged in combination with a vehicular cover is constructed to include a flexible cable sheath having a plurality of cable strands directed therethrough, with a forward ring mounted to a forward distal end of the sheath and cables. An anchor block mounted fixedly to a rear distal end of the cable has an anchor ring secured thereto for positioning with a vehicular passenger compartment. The cables and sheath are directed through a grommet portion of a vehicular flexible cover, with a lock mechanism mounted through the forward ring. A modification of the invention includes alarm structure mounted within the anchor block.

Abstract: A microprocessor controlled automobile security system provides several features for enhanced operability. The system allows a receiving unit to learn a plurality of operating codes from a plurality of uniquely coded transmitters with which it can operate, thereby allowing each transmitting unit to be sold separately from each receiving unit. The system also allows for an operator to personally set the threshold at which a signal detected by a shock detector will result in an alarm being triggered. The system is further selectively operable in either a manual arming mode or a passive arming mode. The system also allows selective operation in either a full current sensing mode in which either a detected shock above an absolute threshold or a .DELTA. threshold, or current flow above a predetermined level, will trigger an alarm system or operation in a shock and current integration mode in which if a detected current exceeding a predetermined threshold and a shock above an absolute or .DELTA.

Abstract: A vehicle indicator system is set forth for a vehicle that has first and second instrumentation indicator lamps for indicating the condition of first and second vehicle systems. Instead of the first indicator lamp having a backup lamp in case the first indicator lamp burns out, the second indicator lamp serves a dual purpose as the backup lamp for the first indicator lamp.

Abstract: A prealarm system is provided for an anti-theft alarm where a signal from a displacement/vibration detector is picked up by a one-shot timer circuit. If no other activation signal is picked up after the first signal is received a main control alarm circuit is activated for (1) driving a siren circuit to generate a short chirp sound as an audible warning, and (2) a flashing circuit to flash a light for a preset period of time as a visible warning. If the number of activation signals received subsequent to the first are greater than a predetermined threshold number, or the activation signal continues for a predetermined period of time, the main control alarm circuit is activated for driving, (1) the siren circuit to give a normal audible signal alarm, and (2) both, the flashing circuit for flashing a light and the dome light control to provide visible signals.

Abstract: An inductive motion sensor (MS) connectable to a subject (16), the motion sensor having a coil (4) and a magnet member (3) movable relative to the coil (4). The magnet member (3) has at least four magnetic poles, whereby the number of south poles (S) is equal to the number of north poles (N). The pole strength of the magnetic poles is dimensioned and the magnetic poles are located on the magnet member (3) such that the magnet member (3) is situated in a neutral equilibrium position in a uniform magnetic field with respect to the forces exerted on the magnetic poles by the magnetic field.

Abstract: A vehicle security system provided with a plurality of environmentally sensitive sensors determines the number of environmentally sensitive sensors that are activated, and generates an attack alarm signal when at least a predetermined number of environmentally sensitive sensors are activated, the predetermined number being greater than one, and generates a tamper alarm signal when a number of environmentally sensitive sensors less than the predetermined number are activated. In a system having one or more environmentally insensitive sensors and a plurality of environmentally sensitive sensors, an attack alarm signal is generated when an environmentally insensitive sensor is activated or at least a predetermined number of environmentally sensitive sensors are activated, the predetermined number being greater than one, and a tamper alarm signal is generated when no environmentally insensitive sensor is activated and a number of environmentally sensitive sensors less than the predetermined number are activated.

Abstract: An automobile alarm system with noise reduction function utilizes a built-in function in a single-chip computer, which is adapted to control the alarm system, to prevent the system being damaged by the noise, while the noise is presented in the form of high voltages, occurring during the operation of the engine. The alarm system has a current detector circuit to sense the presence of noise, and a one-shot circuit to selectively activate/inactivate the single-chip computer temporarily.