Abstract: An IF system that makes satisfactory use of a first IF stage frequency selected from between 108 MHz and 132 MHz to thereby provide an IF system that can be utilized in radios intended for reception in all land mobile frequency bands. The first IF stage (17) includes a high tolerance crystal filter (24) that contributes to the satisfactory reception performance of a radio so equipped.

Abstract: In a radio having an in phase multiplier (A) for providing an in phase detected signal, a detection unit for receiving this signal and for determining whether this signal includes any negative polarity components which would indicate that a viable broadcast signal does not exist on the incoming frequency of interest. This detection unit can include a comparator (11) for comparing the incoming signal against a selected reference value. The invention can also include a signal quality evaluation unit (58) for providing either a digital or analog quality signal that can also effect the output and be used by appropriate processing circuitry to further refine the channel selection process.

Abstract: A vehicle mounted mobile transceiver (11) communicates via a secondary mobile unit (51) with a short range portable unit (10). The portable unit (10) can be either a cordless microphone or a transceiver. The portable unit (10) allows a remotely positioned operator to transmit messages to a base station (13). To ensure security and reliable operation, the portable and vehicle mounted units use digitized codes for ID and instruction purposes. These codes are newly generated from time to time by the vehicle mounted unit and are imparted to the portable unit via a battery charging interface by modulating the battery charging signal with the reset and digital data signals. An improved remote squelch detect is also provided.

Abstract: A power driver having a power transistor (15) uses a disable unit (17) to disable the transistor (15) upon sensing a short circuit condition. No current sense resistors are used. The base-emitter voltage of the transistor (15) is compared by a comparator (14) with a reference signal provided by a reference signal unit (16) to determine the existence or absence of a short circuit condition. In the presence of a short circuit, the comparator (14) provides a fault detected signal to the disable unit (17). The disable unit functions to deny the control signal to the transistor (15) and to ground the base of the power transistor (15) to thereby doubly ensure disablement. In addition, the disable unit (17) has memory and will disable the transistor (15) until the control signal recycles.

Abstract: A current-saving CMOS signal input buffer is provided, having at least two CMOS output transistors (each having an input) connected in complementary fashion with a common output taken therebetween, complementary current mirrors coupled to the output transistor inputs, an input signal capacitively coupled to at least one of the output transistor inputs, a reference impedance coupled between the complementary current mirrors, and isolation impedances coupled between the complementary current mirrors and the output transistor inputs.

Abstract: An incremental count display system having a display (14) for displaying odometer information and trip odometer information. The display includes a display overflow indicia (21) that will not be permanently activated unless the odometer itself has been factory preset to an initial starting point of other than zero. Otherwise, the overflow indicia (21) must be reset with each display cycle. The trip odometer provides for an accurate count of trip mileage, even during a trip that includes an odometer memory rollover cycle. In addition, the trip odometer display makes use of a masking technique to avoid automatically writing to non-volatile memory (12). Also, an error indicia can be displayed in response to early failure detection.

Abstract: A meter drive inhibit circuit is provided whereby an erroneous jump of the meter pointer upon system power-up or subsequent microcomputer reset operation is inhibited. A pulse generator is utilized to produce output pulses relating to the rate of rotation of a drive shaft in a typical tachometer application. Such output pulses are provided to a meter drive circuit which in turn provides an output to an electromechanical meter. Such electromechanical meter will display an output related to the time average value of pulses input to the meter drive circuit. An inhibit circuit stage is connected to the meter drive. A microcomputer is utilized to sense the power-up condition of the meter circuit and activate the inhibit stage. When activated, the inhibit stage will prohibit the meter drive from providing an output to the meter and thereby prevent the erroneous jump of the meter pointer upon system power-up.

Abstract: A solenoid driver control circuit for use with solenoids, the circuit including a current sense unit (12) for providing a current sense signal and a solenoid drive unit (13) for selectively allowing current to flow through the solenoid (11) from a power source (14). The circuit also includes a threshold comparator unit (17) for comparing threshold signals with the current sense signal and for providing an output signal that can control the solenoid drive unit (13), a minimum threshold unit (18) for providing a minimum threshold, a maximum threshold unit (19) for initially providing a maximum threshold until a peak current flow through the solenoid (11) has been established, a first timing unit (21) to periodically provide increased threshold signals for specified durations of time, and a second timing unit (41) for initially providing an increased minimum threshold signal at the outset of a control cycle.

Abstract: A dispatch trunked radio system which provides duplex or simplex telephone interconnect communications to subscriber units is described. The system allows duplex capable trunked system subscriber units to establish a full duplex communication link with conventional land based telephone interconnect service in accordance with a method which unifies the operation of the trunked system subscriber units, a plurality of trunked system repeaters, a trunked system central control unit, and a telephone interconnect control unit. The method of the present invention also provides improved trunked system performance by allowing simultaneous transmission and reception of channel controlling information.

Abstract: A multi-channel RF telephone system that utilizes a dedicated channel status monitor to develop a list of available communications channels, and a common channel transceiver to transmit this list to the telephones. The telephones select a channel to use from this list by sequentially accessing the list a number of times based upon, at least in part, an identification number uniquely assigned to the telephone in question. If the selected channel is in fact unavailable, the telephone can update the list it maintains independently.

Abstract: A fault detection and response system having particular applicability for use with oxygen sensors and closed loop control systems. The system includes a confidence measuring unit as part of a fault control unit (26) that maintains a measure of confidence with respect to the recent operating history of the oxygen sensor. This measure of confidence is increased upon detecting state changes of the oxygen sense signal through use of a state change detector (24), and decreased upon detecting that an integrated form of the oxygen sense signal has attained a predetermined limit as sensed by a limit detector (22). Based upon this measure of confidence, the system can respond to perceived fault conditions in various ways. In general, with a high measure of confidence being present, the system will favor closed loop control even in the presence of a perceived oxygen sensor fault. Similarly, with a low measure of confidence, the system will favor open loop control.

Abstract: A method and apparatus for calibrating a sensor output that includes a logic unit (11) for receiving uncalibrated sensor signals from a sensor (13) and for receiving data from a data base unit (12) regarding test points that relate to that particular sensor's (13) performance. Based upon these inputs, the logic unit (11) can provide a sensor reading calibrated to a preselected standard.

Abstract: An invention for detecting loss of input signals to a distributorless ignition system (17) and for providing appropriate responses upon detecting fault conditions. If a SPOUT signal (31) faults low, the invention will control ignition sequence through use of a CID signal (14), and the CID signal (14) and a PIP signal (13) will be operably substituted for the missing SPOUT signal (31) to assure timely ignition. If the SPOUT signal (31) faults high, the CID signal (14) will again be utilized to sequence the firing sequence and the PIP signal (13) will be substituted for the SPOUT signal (31). If the CID signal (14) faults, firing sequence will continue to be incremented in response to receipt of the SPOUT signal (31). In addition, the invention provides for recovery of normal operation should any of the above fault conditions prove to be transient.

Abstract: An inductor housing having a platform for supporting an inductor and a standoff unit for supporting the platform away from a conductor board such that various electrical components can be installed on the conductor board between the inductor platform and the conductor board surface. The inductor housing also has a hole disposed therethrough such that the inductor housing may serve as an insulating standoff support member for connecting a conductor board to a chassis.

Abstract: This invention relates to a fault detect and signal routing device that may be used to monitor and control redundant signals. The invention includes an input/output unit (11) for receiving the redundant signals and an output for outputting one of the signals. The input/output unit (11) also provides logic signals that relate to the received signals. A fault inhibit unit (12) receives the logic signals and provides outputs that relate thereto to a time delay unit (13), a fault detect unit (14), and a signal route control unit (16). The fault detect unit (14) serves to compare signals from the time delay unit (13) and the fault inhibit unit (12) to determine if certain kinds of signal faults have occurred. If one has, the fault detect unit (14) provides fault signal. The signal route control unit (16) receives the input signals and the signals from the fault inhibit unit (12) and provides a control signal to the input/output unit (11) to control which input signal is provided to the output.

Abstract: A non-volatile memory storage system having non-volatile memory (10) and volatile memory. The non-volatile memory (10) will have its most significant bits memory locations (11) periodically updated in response to a growing count of data. The least significant bits information reflecting such count will be maintained in volatile memory except during power down conditions. During power down conditions, the least significant bits will be stored in a separate plurality of memory locations (12) contained in the non-volatile memory (10).