Abstract: A method for and selective call communications unit (CU) arranged and constructed for extended battery life includes a first receiver having low power consumption, preferably operating an a duty cycle, for receiving a call signal to provide an enable signal, in one aspect conditioned on a match of a selective call address to an address for the CU; and a messaging receiver, activated by the enable signal, for receiving a message intended for the CU. These methods can result in a battery life for the CU approaching a shelf life of the battery.

Abstract: A method and apparatus for time domain reflectometry sensing of moisture in a test material. The sensor (200) having a generally helical shaped electrode (206) and at least one secondary electrode (208) spaced apart from the generally helical shaped electrode (206) to enable the test material to be present in the space (210) between the helical shaped electrode (206) and the secondary electrode (208). A wave pulse generator (202) is coupled to the generally helical shaped electrode (206) and the secondary electrode (208) that results in a reflection of the generated wave from the wave pulse generator (202). Additionally, a reflected pulse detector (204) is coupled to the generally helical shaped electrode (206) and the secondary electrode (208), in which the reflected wave pulse detector (204) receives a reflected wave pulse from the wave pulse generator (202).

Abstract: A pullable overtone crystal oscillator (201) includes an impedance buffer (217) for buffering an input impedance (109) to an amplifier stage (203). This structure enables construction of an overtone oscillator with increased pullability because a drive level of a crystal (221) can be set independent of the input impedance (109) of the amplifier stage (203).

Abstract: Utility meter assembly (10) includes a utility meter (11) having an external housing (12) adjacent to which is mounted a remote meter reading module housing (25) that preferably is mounted to a pair of upstanding cylindrical posts (15 and 16) that rise from the utility meter housing (12). Preferably, flexible pins (32), which preferably are part of the module housing (25), bias the module housing (25), and a ground plane plate (26) within the module housing, towards a conductive surface (14) of the utility meter housing (12). The ground plane plate (26) coupled to the meter housing (12) and to the conductive surface (14) takes advantage of the meter as an extended ground plane or a counterpoise and thus increases the radiation efficiency of the antenna. This configuration permits the use of a shorter antenna (23) for power efficient transmission of meter data.

Abstract: A data transmission device (11; 111,) for use in a system (10) comprising a plurality of such devices is described along with a corresponding method of data transmission. A data signal (at 23) is provided for transmission and a timer apparatus (16, 18; 16, 118, 160) establishes a sequence of maximum time intervals (6 hours; 6 hours and 20 seconds) during which the data signal can be transmitted. A transmitter (18, 24, 25; 118, 24, 25) transmits the data signal during each of these maximum time intervals. The timer apparatus (16, 18; 16, 118, 160) generates a random number (steps 33, 54; steps 172, 195) for each one of the maximum time intervals, and the transmitter (18, 24, 25; 118, 24, 25) determines the transmission times for the data signal in accordance with the random numbers provided for each of these maximum time intervals.

Abstract: A drive circuit for driving a capacitive load (4) and for producing a signal (FIG. 2b, 3b, 4b, 5b) indicative of the condition of the load, the circuit comprising: a FET (26) applying current to the load; a resistance (30) sensing the level of the applied current; a differential amplifier (32) detecting when the sensed level exceeds a predetermined threshold; and a bipolar transistor producing a control signal (FIG. 2b, 3b, 4b, 5b) to limit the applied current until the load current falls below the threshold, whereby the control signal is a pulse width modulated signal whose pulse width is indicative of the condition of the load.

Abstract: A bridge circuit (2) for driving a load such as an electric motor (36) in one direction or an opposite direction as desired, the circuit comprising first (4) and second (24) parallel arms for connection across an automobile battery supply voltage, each arm comprising an FET switch (6, 26) and a bipolar PNP transistor (8, 28) connected in series via mid-point nodes for connection across the load. In each arm the intrinsic diode of the field effect transistor and the base-emitter junction diode of the PNP transistor are arranged to conduct forward-biased current in opposite directions. In this way, no current path is provided through the arms of the bridge circuit in the event that the voltage supply to the circuit is reversed.

Abstract: A short circuit protection arrangement (2) for a driver circuit (9, 16) including a diode (24) for sensing the presence of a short circuit condition at the driver circuit output; and an arrangement (18, 20, 22, 24) for sensing the discontinuance of the short circuit condition by establishing an inductive current at the output upon the occurrence of the short circuit condition and sensing the increase in voltage at the output due to the inductive current upon discontinuance of the short circuit condition. Such a protection arrangement may be used for each of a plurality of driver circuits (40, 50, 60, 70, 80) utilizing a common inductance (36, 38).

Abstract: A circuit for operating a high power ionizable discharge device such as a xenon flash tube or other gas filled lamp includes a trigger circuit for gating the device periodically to produce a discharge condition. A capacitive energy storage circuit discharges through the device when the device is placed in a discharge condition. A low resistance power supply circuit charges the energy storage circuit. First and second sensing circuits respectively detect the charge level of the energy storage circuit and detect discharge of the discharge device. A switching device comprising a zero crossing solid state relay controls the energization of the power supply circuit. A control circuit is operated by the first sensing circuit to operate the switching device so that the power supply circuit is deenergized when the energy storage circuit is charged to a predetermined level.