Abstract: A battery protection system includes at least a first fuse arranged for connection in series between a load/charger and one or more cells. A shunt switch is connected on the load side of the first fuse. A control subsystem features logic which monitors the cell voltages, determines when any cell voltage is above a predetermined level, and closes the switch causing the first fuse to blow when the cell voltage is above the predetermined level to prevent overheating, a rupture, or an explosion.

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 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: A personal security system includes at least one movable transmitter adapted to produce an emergency signal transmission when activated and a plurality of transceivers adapted to receive emergency signal transmissions from the movable transmitter. The received strength of an emergency signal received by one of the transceivers is compared with the received signal strength of an emergency signal received by other of the transceivers, and an alarm signal is produced by a transceiver in response to receipt of a transmission whose signal strength is stronger than any other transmission signal strength to which it has been compared. The alarm signal may include a code identifying both the activated movable transmitter and the transceiver producing the alarm signal.

Abstract: A personal security system includes at least one movable transmitter adapted to produce an emergency signal transmission when activated and a plurality of transceivers adapted to receive emergency signal transmissions from the movable transmitter. False alarms are avoided by inhibiting multiple transmissions by a movable transmitter within a predetermined time period.

Abstract: An autodyne microwave motion-detection system includes a supervisory circuit for monitoring the operating status of the microwave energy-producing component of the system. According to a preferred embodiment, the supervisory circuit of the invention comprises a relatively low-cost, "general purpose UHF" diode, i.e. a multipurpose diode commonly used in circuits designed to accommodate UHF frequencies of up to only about 3 Gigahertz. The supervisory diode is positioned within, or in close proximity to, the resonant cavity of the microwave energy-producing element, the latter being designed to produce microwave energy at a substantially higher frequency (e.g., 10.5 Gigahertz). Due to its close proximity to the microwave energy-producing element (e.g. a Gunn diode) and its presence within the energy field produced thereby, the supervisory diode develops a small, but readily detectable, voltage whenever such element is radiating microwave energy.

Abstract: An intruder detection system is provided with circuitry for reducing the risk of false alarms from spurious sources. Such circuitry comprises a pulse generator for producing current pulses of predetermined pulsewidth and amplitude each time the output of an intrusion detecting element exceeds or falls belows a preset threshold level, an integrating circuit for integrating the output of the pulse generator, threshold sensing means for activating an alarm when the integrator output exceeds a preset level, and a timing circuit for establishing a predetermined time interval and for discharging the integrating circuit in the event the integrator output fails to exceed such preset level within such predetermined time interval. According to a preferred embodiment, means are provided for resetting the time interval each time the detector output exceeds or falls below the selected threshold level.

Abstract: A high speed antenna coupler and method for rapidly switching binary weighted values of inductance and capacitance into and out of the circuit between an antenna and a utilization circuit without unacceptably degrading the coupler or slowing the switching action. PIN diodes are utilized as switches and the control wires for the PIN diodes are disposed interiorly of the copper tubing which forms the inductance elements. The control wire for a particular inductor is withdrawn from the interior of that inductor adjacent the mid-point thereof so that the control wire will be at the same RF potential as the inductor being controlled. Two diodes are utilized for each inductor, one connected to each end thereof, so that only half of the normal reverse bias is required for switching purposes. Where a transformer is utilized to couple the antenna to the utilization circuit, the control wires may be disposed interiorly of the copper tubing which forms the winding of the transformer.