Abstract: Digital signals transmitted twice are decoded by a receiver arrangement which determines the value and deviation of each pair of corresponding signals relative to a selected level. A weighting signal indicative of the deviation (either maximum or minimum depending on the selected level) is assigned to each signal. The value of the signal having the greater weight is selected as being correct. Thus, transmitting signals three times for a majority voting is eliminated.

Abstract: A keyboard with number and volume control pushbuttons is provided with a microcomputer, a digital-to-analog converter, and an output circuit to provide signalling tones to a radio transmitter in response to operation of the number pushbuttons, and to provide volume control signals to a radio receiver in response to operation of the volume control pushbuttons.

Abstract: Noise blanking is provided by amplifying, limiting and detecting received signals. The detected signals are compared with a threshold circuit. The leading edge of each detected signal that rises at a rate greater than a selected rate to exceed an amplitude threshold level produces a blanking pulse of selected time duration. Low as well as high level noise signals are blanked. Slow rising information signals are not blanked, and fast rising information signals of high level are blanked initially for the selected time duration, but are not blanked thereafter.

Abstract: A vehicular radio transceiver is normally powered by a vehicular ignition switch and a transceiver on-off switch both being closed. A latch circuit senses the presence of communication over the transceiver, and produces a latch signal that powers the transceiver despite opening of either of the switches.

Abstract: An attaching device is provided for parallel and spaced cable turns. The device includes an insulating yoke formed from a plate whose thickness is less than the spacing between the cable turns. The yoke is provided with semicircular recesses which fit partially around adjacent turns. A metallic clamp is attached to the yoke and is provided with a recess which opposes one of the yoke recesses to engage only one turn between the clamp recess and the one yoke recess. The device is securely attached but does not short circuit turns, and can be easily and rapidly relocated.

Abstract: Two printed circuit boards are connected together by a female coaxial connector, open at both ends, on one board, and by an elongated pin on the other board. When the boards are fastened together, the pin engages the female coaxial connector from one end. When the boards are separated, a male coaxial connector may engage the female coaxial connector from the other end.

Abstract: Control signals for switching the bandwidth of a filter in a phase locked loop are provided by comparator circuits having time delays at their inputs that vary as a function of the magnitude of changes in the outputs from a phase comparator. These variable time delays permit the comparator circuits to produce an output having a duration of the proper length in order to permit the filter to have a large bandwidth for a long enough time to permit the phase locked loop to become locked.

Abstract: A voltage controlled oscillator for use in a phase locked loop is provided with a first varactor circuit that responds to a control signal to set the center frequency of the oscillator, and with a second varactor circuit comprising a modulation varactor that responds to a modulation signal to cause the oscillator to produce a modulated output. The modulation sensitivity of the oscillator is made relatively constant between upper and lower center frequencies by applying a portion of the modulation signal to the first varactor circuit in addition to the control signal.

Abstract: A scanning receiver is provided with a pause detector which causes the receiver to tune to a priority channel during pauses in the transmission on a nonpriority channel. If a priority transmission is present, the receiver remains on the priority channel until the priority transmission ends. If no priority transmission is present, the receiver is tuned back to the former nonpriority channel.

Abstract: Rapid lock or synchronization between a reference oscillator and a voltage controlled oscillator in a phase locked loop circuit is achieved by a synchronizing circuit. The synchronizing circuit senses the magnitude of the ramp signal produced by the phase locked loop circuit, and produces a blocking signal when the ramp signal exceeds a predetermined level. This blocking signal is applied to one of the oscillators to block that one oscillator pulse during the blocking signal, thus moving the two oscillator signals closer together more quickly, and thus providing lock or synchronization more rapidly.

Abstract: Radiotelephone loudspeaker and handset volumes for different types or modes of operation are set by a single control and stored. After being set and stored, the volume for each mode can be retrieved and applied to an electronic attenuator to automatically provide the desired volume.

Abstract: An improved crystal is provided with an aluminum baseplate, a nickel plating on the aluminum baseplate, and a silver plating on the nickel plating. The nickel is plated on the aluminum baseplate before the aluminum has oxidized to provide high yields of stable crystals.

Abstract: A radio transceiver has a single reference oscillator and a receiving frequency synthesizer and a transmitting frequency synthesizer. The synthesizer frequencies are selected so that the receiving intermediate frequency and a transmitting intermediate frequency (produced by the transmitted frequency mixing with the received frequency) are spaced widely apart. Thus, any beat note between the two intermediate frequencies is outside the passband or filter bandwidth in the receiver circuit.

Abstract: Radio transceivers are provided with a timing circuit that ends or terminates a radio transmission after a first time period, and an audible indication signals the end of the first time period. A battery voltage sensor reduces the period of the timing circuit in response to low battery voltage. Shorter period transmissions are still permitted for emergencies, and an audible indication is provided after the short time period to indicate low battery voltage.

Abstract: A temperature compensating circuit for a piezoelectric crystal includes a thermistor circuit coupled to a transistor to cause the output voltage derived from the transistor to decrease as the temperature increases from a cold temperature toward a middle temperature. As the temperature increases still more, the thermistor causes the transistor to become saturated, and its output voltage increases. An additional thermistor circuit is coupled to the transistor output to cause the output voltage to decrease as the temperature increases toward a warm temperature from the temperature at which the transistor became saturated.

Abstract: A voltage controlled oscillator is provided with one or more varactors connected in series with the frequency determining capacitors of the oscillator. These varactors are in addition to prior art varactors, and increase the tunable range of the oscillator, and improve the frequency variation with control voltage characteristic of the oscillator.

Abstract: Signal level control for an amplifier or the like is provided by a binary counter which counts upward when first operated, and which thereafter counts up and down if continually operated. If the operated counter is stopped after counting up, it counts up when operated again. If the operated counter is stopped after counting down, it counts up when operated again. A digital to analog converter can provide a single control signal from the counter. The user is always assured that the single control signal will increase when the counter is operated again following a prior operation in either direction.

Abstract: A frequency synthesizer utilizing a phased locked loop is provided with input modulating signals for the reference oscillator and for the voltage controlled oscillator. Where the frequency of the reference oscillator must be divided, a time delay circuit between the input modulating signal and the voltage controlled oscillator is provided in order to eliminate or appreciably reduce deviation magnitude responsive distortion with respect to input modulating frequencies.