Abstract: A speed-dependent ignition controller and method utilizes a sensor output signal to provide spark occurrence and dwell initiation at retard and advance angles for an internal combustion engine. The sensor signal has a pulse width proportional to the difference between a desired ignition advance and retard angle. At low rpm, the sensor signal is inverted to produce a retarded ignition angle while at high rpm's the signal is utilized without inversion to produce an advance ignition angle.

Abstract: An alternator regulator utilizes a non-linear, stepped ramp for use by a comparator which compares the ramp voltages with the alternator output and controls the switching of the excitation current accordingly. The non-linearity allows for tight control at low and normal alternator load levels, but also prevents a loss of accurate control at higher loads. A D/A converter makes the non-linearity possible, thus preventing the loss of control pulses at high loads, which loss can cause a large ripple component and excessive drop in average voltage output.

Abstract: An improved radiotelephone includes a unique microprocessor and peripheral devices for controlling the operation of portable or mobile radio transceivers in a cellular-type radiotelephone system. The microprocessor is coupled by a data interface unit and synchronization unit to the radio transceiver for transmitting and receiving Manchester-coded supervisory signalling having a 10 KHz bit rate. The microprocessor is also coupled by a unique self-clocking serial data bus and unique interface adapters to the radio transceiver for controlling the operating frequency, audio signals and transmitted RF signal thereof, to a keyboard for sampling the keys thereof, an off-hook switch and display for displaying telephone numbers, and to serial number and telephone number memories for accessing the stored serial and telephone numbers assigned to the radiotelephone.

Abstract: A unique method and apparatus for efficiently assigning duplex radio channels and scanning duplex radio channels assigned to mobile and portable radiotelephones in a cellular communications system is described. Each cell includes a base station radio having a signalling channel and a plurality of voice channels, and a base site controller adapted to utilize the methods embodying the present invention for controlling communications paths to mobile and portable radiotelephones. The base station radios include a signalling transceiver operable on the signalling channel, a plurality of voice transceivers each operable on a voice channel, and a scanning receiver for sampling the signal strength of active radiotelephones. Transmitters of signalling transceivers and voice transceivers are combined and coupled to an omnidirectional antenna; and the receivers of the signalling transceiver, voice transceivers and scanning receiver are couplable to one or more of six sector antennas.

Abstract: An improved encoder/decoder circuit which utilizes a phase locked loop frequency synthesizer configuration to permit both encoder and decoder operation. In addition, a sampling filter detector is employed to permit monolithic integration of the circuit and minimize sensitivity to vibration. The sampling filter detector has digitally controlled bandwidth which permits rapid response to reverse burst turn-off. In addition, the circuit includes a pulse adder to implement an energy limited reverse burst turn-off mode.

Abstract: In a frequency synthesizer phase locked loop including a reference oscillator, a variable reference divider (.div.M), a sample and hold phase detector, a loop filter, a voltage controlled oscillator and a variable divider (.div.N), a voltage converter for controlling the voltage of a control input to the voltage controlled oscillator is disclosed. In the preferred embodiment, the voltage converter has its input connected to the output of a first reference divider in the variable reference divider (.div.M) and its output connected to a control input (varactor diode) of the voltage controlled oscillator. The voltage converter clamps the divider reference signal from the first reference divider and provides a negative voltage level output to bias the varactor diode of the voltage controlled oscillator. Thus, the tuning range of the frequency synthesizer is increased.

Abstract: An improved channel scanning radio which automatically monitors a channel being monitored by the scanning circuitry at the time of the microphone is taken off-hook by treating that channel as a priority channel for a short period after the microphone is returned to the hang-up position. This permits the operator to automatically monitor a channel of interest without stopping the scan function.

Abstract: Apparatus for processing received Loran C signals and compensating for envelope cycle discrepancy (ECD). A measure of ECD is determined during the fine settle operation and compared to a reference value which is an average over a period of time. If the difference between the reference and the ECD measure is greater than a threshold, the decision made by the fine settle operation is rejected and the fine settle process is restarted. If the difference is less than the predetermined threshold the decision is accepted as being an accurate fine settle determination.

Abstract: A television transmission system for asynchronously transmitting a television picture as a plurality of video samples over a narrow bandwidth medium from at least one remote transmitting site to a receiver at a base station. Improved synchronization between the transmitter and receiver are achieved by a dotting pattern consisting of alternating logic ones and zeros being sent by the transmitter to precede the video samples such that a sampling clock at the receiver synchronizes to the phase of the dotting pattern and thereafter samples the video signal. The video signals are also preceded by at least one predetermined digital word which identifies the particular remote transmitter and prepares the receiver to begin receiving the video samples. DC restoration circuitry determines the average value of the incoming video signals and to add an appropriate DC offset to the video signals to correct for any change in the gray scale of the video samples.

Abstract: A frequency modulator for radio frequency (RF) signals is described that symmetrically modulates the RF signal with either binary signals or voice signals without distorting the amplitude of the binary signal near bit edges. The inventive frequency modulator includes a reference signal generator, a phase comparator for comparing the reference signal and a feedback signal to provide an error signal, a filter for filtering the error signal, a voltage-controlled oscillator (VCO) responsive to the filtered error signal for generating an output signal, a divider for dividing the VCO output signal by a predetermined number to provide the feedback signal, circuitry coupled to the VCO for modulating the VCO output signal with the binary signal, and circuitry coupled to the divider for varying the predetermined number of the divider between a first predetermined number and a second predetermined number in response to the binary signal.

Abstract: A data communications system is described that covers a geographic area divided into a plurality of non-overlapping zones and includes a general communications controller (GCC), a plurality of channel communications modules (CCM) and associated transmitters and receivers, and a plurality of portable radios. Message signals carrying alphanumeric information are communicated between the GCC and the portable radios by way of a radio channel. Each CCM takes a signal strength measurement every time it receives a message signal from a portable radio. The GCC gathers the signal strength measurements from the CCM receivers receiving the same message signal and computes an adjusted signal strength for each zone. The GCC then selects the zone having the largest adjusted signal strength for determining the location of the portable radio that transmitted the message signal.

Abstract: A trapped energy piezoelectric resonator for oscillator and multiple resonator applications has a piezoelectric substrate with electrodes disposed on each of its major surfaces. These electrodes are further comprised of a plurality of electrically interconnected and acoustically coupled sub-electrodes. The resonant frequency of these resonators may be controlled by varying the separation and, therefore, the acoustic coupling between the sub-electrodes. This resonator may be used in the feedback loop of an oscillator circuit as the frequency determining element. It may also be used to provide a resonator on a substrate carrying resonators of significantly different frequency.

Abstract: A method is disclosed whereby adjacent transmitting antenna arrays may be more closely spaced to each other and to receiving antenna arrays while still maintaining a high level of isolation between arrays. In each antenna array, first and second parts thereof are identified. The two parts of each transmitting array are driven in phase quadrature with each other and at substantially equal power levels, and the antenna arrays are spaced sufficiently close to each other so that radiation emitted by one array and received by another array undergoes a cancelling effect before reaching the RF generator associated with the other array. The two parts of each receiver array are coupled to their associated receiver by a signal path such that substantially quadrature phasing is established between the first and second parts thereof to cause received radiation to cancel in the signal path before reaching the receiver.

Abstract: This invention is directed to a same frequency repeater (SFR) for use in a multiple SFR system in which only one SFR at a given time is allowed to retransmit a received signal thereby preventing simulcast distortion which could occur due to multiple SFR retransmissions. The SFR includes a receiver for receiving a signal carrying information at a given frequency and a transmitter for rebroadcasting the received signal at the given frequency. A mechanism is provided for keying the transmitter upon the reception of a received signal. A detector senses if a predetermined pilot tone is carried by the received signal. A mechanism responsive to the detection of the pilot tone inhibits the keying of the transmitter if the pilot tone is detected before the transmitter is keyed. A tone generator encodes the output signal of the transmitter with the pilot tone.

Abstract: A communications receiver squelch circuit for use in frequency modulation systems which has tight squelch sensitivity. The squelch circuit includes two audio limiters and provides improved squelch sensitivity and squelch action that is independent of carrier modulation and significantly minimizes squelch clamping and squelch boost characteristics.

Abstract: A method for preparing a printed circuit board for mounting of surface mounted RF components such that the lead inductance of the components is minimized. The process consists of producing plated through apertures in the printed circuit board to create a component body hole with lead contacts extending to the edge of the component body hole. The resulting aperture is then blanked to remove portions of the metal lining to provide electrical isolation between the lead contacts while maintaining lead contacts that extend to the edge of the component body hole. A component is then soldered into position such that solder is wicked through the plated through apertures to create solder contact of the leads at the edge of the component body hole. This results in substantial reduction in lead inductance improving RF amplifier gain and stability and improving bandwidth characteristics.

Abstract: A unitary retainer is disclosed for mounting and holding a printed circuit board onto a support panel, another printed circuit board or the like. A retaining channel receives a forward portion of a board inserted thereinto at a corner of the board. The channel locates a side edge of the board and clamps opposite faces of the board. A lead-in guides the board into the channel. A locking portion holds the board in the retainer.