Abstract: Measuring the critical value of a parameter of a sensor in a security system (e.g., battery voltage) is performed at a time when the critical value is most likely to be reached, and the critical value information is sent from the sensor to a system controller at a time when the information is most likely to be successfully received.

Abstract: An apparatus and method for reducing errors in a battery powered sensing circuit uses two pull-up resistors. The first resistor has a value selected to minimize battery drain and the second resistor has a value selected to reduce dendrite or other parasitic parallel resistance. The resistors are selectively connected to the circuit based on a predetermined sequence and/or time interval.

Abstract: Information in the form of redundant message packets is sent between a remote device and a host device, e.g., a wireless security system. In order to conserve energy, the frequency of trigger events in the remote device is determined, and the number of redundant message packets sent is based on the determined frequency.

Abstract: An apparatus and method for sending messages from a sensor to a system controller in a wireless security or monitoring system, including processing signals from the sensor and generating message packets which include information derived from the sensor signals.

Abstract: In a security or monitoring system having a system roller and one or more sensor/transmitters, information is sent from the transmitter to the system controller in message packets. As improved message packet protocol provides a front porch pulse, a set of synchronization bits, a start bit, a set of information bits, a first stop bit, a set of error detection bits, and a second stop bit.

Abstract: The present invention relates to a magnetic sensor apparatus (21) for use in a remote meter monitoring system (20) for remotely monitoring the dials (54a-e) of a utility meter (56) by use of Hall Effect devices (40-49). The Hall Effect devices (40-49) are concentrically positioned about the axis of rotation of a pointer member (64) having a permanent magnetic member (66) attached to a free end thereof. The Hall Effect devices (40-49) are axially displaced from the permanent magnetic member (66) and are in alignment with the circumferential path of travel of the permanent magnetic member (66). A microprocessor (68) electrically interconnected to the Hall Effect devices (40-49) selectively drives each of the Hall Effect devices (40-49). The microprocessor (68) further monitors the Hall Effect devices (40-49) and obtains output signals therefrom representative of the angular position of the pointer member (64).

Abstract: The present invention relates to an optical sensor apparatus (21) for remotely monitoring a utility meter or the like. The optical sensor apparatus (21) includes optically sensitive detector, in this case, a dynamic RAM device (40) which consists of an array (42, 44) of light sensitive elements. Light from a light source (56) is reflected off the faceplate (52) of the meter. Microprocessor control system (100) operatively interconnected to the optically sensitive dynamic RAM device (40) controls the exposure of the RAM device (40) to the light. The microprocessor control system (100) further determines the angular position of the individual pointer members (50) of the meter by correlating a binary image stored in memory to a predetermined geometic shape. The microprocessor control system (100) further includes logic for converting the angular positions of the pointer members (50) of the meter stages to a decimal value representative of the meter reading.

Abstract: A system for minimizing synchronization errors in a phase-locked loop having a sequential phase detector for determining the phase difference between the output of the VCO of the phase-locked loop and a periodic control signal. Control circuitry is provided so that the control signal is enabled as an input to said sequential phase detector for a relatively short time window which comprises a small fraction of the control signal cycle period beginning just before a control signal is anticipated and the signal is disabled for the remainder of said control signal cycle period. Provision is made for the phase detector to process only the first control signal in any given enable time window. Additional circuitry is provided to disable the control circuitry when the phase locked loop is detected to be out of lock.