Abstract: A high speed logic latching circuit consists of a pair of inverters and feedback switches used to latch the inverters. A pair of input switching means allows data to enter the latch when the latch is disabled. This configuration allows for high speed, reduced substrate area and true complementary outputs.

Abstract: The invention is a synchronized communication system for effectively transmitting messages to a remote mobile receiver where the system includes a plurality of transmitters operating on a single RF communication channel. The system includes a central wide area transmitter which transmits messages over a wide area. The system also includes a plurality of local transmitters which transmit messages over a local area within the wide area served by the wide area transmitter. The transmitters of the system are coordinated by a synchronization link which allows the central wide area transmitter to be keyed only when the local transmitters are not keyed. Correspondingly the synchronization link only allows the local transmitters to be keyed when the central wide area transmitter is not keyed. Normally the synchronization link keys and dekeys the central wide area transmitter and local transmitters in a normal timing cell pattern.

Abstract: A coaxial dipole antenna includes a first radiator which is approximately one quarter wavelength long. A second radiator exhibits length less than one quarter wave length and is coupled to the feed port by a reactive element which has an electrical reactance which is insufficient to increase the electrical length of the second radiator to one quarter of the wavelength. The length of a dipole antenna is substantially shortened while an effective aperture of one half wavelength is maintained by causing a portion of the transceiver housing to radiate in phase with the antenna.

Abstract: A radio frequency transceiver is provided in which the crystal resonator and monolithic crystal filter devices therein all operate at or near the operating frequency of the transceiver, and which employs a single piezoelectric element to achieve the functions of receiver signal filtering, transmitter signal filtering, receiver local oscillator signal generation, and transmitter local oscillator signal generation. To achieve these functions, a crystal resonator and a monolithic crystal filter are situated on the same substrate of piezoelectric material. The crystal resonator portion of the piezoelectric device is employed to control the frequency at which a local oscillator generates radio frequency energy. Such crystal controlled local oscillator is shared by a receiver mixer circuit and a transmitter mixer circuit. Switching circuitry is employed to switch the crystal filter portion of the piezoelectric device from the receiver signal path to the transmitter signal path.

Abstract: In a transceiver, a multiple function switch decoder includes means for detecting actuation of the switch and means for monitoring the status of the receiver. A timer responsive to the monitoring means and detecting means establishes a predetermined time interval following each switch actuation or each received message of predetermined type. When the switch is actuated during the time interval the transmitter is enabled. When the switch is activated outside the time interval the receiver audio is activated so the user may monitor the channel. During the first switch actuation in any given time interval an encoder is enabled. On subsequent switch actuations during the same time interval the encoder is inhibited. This allows a single switch to perform a plurality of transmitter and receiver functions.

Abstract: A computer driven, informational display system is disclosed which visually displays selected information in real time. The arrangement is particularly adapted for displaying pricing and other associated information in retail establishments which utilize the standard Universal Product Code for the items of merchandise for sale. The particular bar code forms a unique address for respective remote display modules at selected locations throughout the store. A source of computer-based information is applied to all of the remote display units in parallel. When a particular display module detects its unique address, the information to be displayed, which follows the addressed code, is processed and used to control the operation of an LCD display.

Abstract: In accordance with the present invention there is provided an amplifier and integral signal shunt attenuator. The amplifier consists of an active amplifying device that is normally biased for signal amplification. The active amplifying device has a characteristic signal transfer impedance between its input and output and a characteristic signal shunt impedance across its input. The amplifier is configured such that the power dissipated by the active amplifying device may be limited. During transmission standby, the active amplifying device may be rebiased to lower the shunt impedance with respect to the transfer impedance. Thus, the undesirable signal is no longer fed-through the transfer impedance but is substantially shunted across the relatively low shunt impedance.

Abstract: An apparatus and a method utilizing a localized electrical field to precisely determine the surface contour of a substantially flat wafer of piezoelectric material having a slight convexity in its opposing faces.

Abstract: A digital voice storage mobile control terminal adapted for use in multiple unit land mobile radio communications system. The mobile control terminal utilizes up to eight 64K dynamic RAMs to store up to 42 seconds of speech comprising up to eight separate messages as well as a CVSD encoder-decoder to digitize speech messages.

Abstract: A voltage controlled oscillator includes a main varactor diode coupled to a frequency resonating circuit to produce an output frequency in response to a control voltage. A secondary varactor diode of an appreciably lower voltage to frequency sensitivity ratio is coupled to the main varactor diode. A modulation input circuit is coupled to the secondary varactor diode to enable modulation of the resonating output frequency. A linearizing circuit is coupled to the secondary varactor diode and tracks the main varactor diode capacitance to continuously adjust the bias voltage of the secondary varactor diode to provide constant carrier modulation deviation.

Abstract: A planar inductance element includes a generally flat substrate of electrically insulating material. First and second substantially flat spiral coils, having respective inner and outer ends, are disposed on opposite sides of the substrate. The coils are spiraled in the same direction as viewed from one side of the substrate with one coil spiraling out and one spiraling in. The inner ends of the coils are joined through the substrate to couple the coils in series. The outer ends of the coils provide terminals for the inductor. The means/methods are disclosed for discretely and progressively trimming the inductor.

Abstract: An antenna is provided which exhibits an overall shortened length with respect to the length of the conventional sleeve dipole type antenna. The antenna includes an upper radiating element coupled to a tank circuit to induce resonance at a first resonant frequency and further includes a helical element electrically coupled to a sleeve member which cooperate to resonate at a second resonant frequency.

Abstract: An antenna is provided which exhibits a low profile. The antenna includes a counterpoise of electrically conductive material and a passive element oriented substantially parallel thereto. The ends of the passive element are electrically coupled to the counterpoise surface. An active element of electrically conductive material includes a middle portion and first and second outer end portions. The middle portion is situated adjacent and spaced apart from the passive element by a predetermined distance and in a parallel relationship therewith. The first outer end portion of the active element is bent toward the grounded end of the passive element nearest thereto. The first outer end portion represents a feedpoint of the antenna with respect to the counterpoise. The remaining second outer end portion the active element is bent towards the remaining end of the passive element nearest thereto.

Abstract: An improved temperature compensation circuit for an oscillator circuit having a frequency response that is parabolic with respect to temperature, including a time dependent ramp signal, an AC integrator for converting the ramp signal to single-sided parabolic voltage functions and means for sampling the resulting time dependent one-sided parabolic voltage functions with respect to a time base at selected times corresponding to ambient temperatures.

Abstract: Improved radio transmitter modulation control circuitry is described which significantly increases the average power of the modulating signal, resulting in enhanced audio signal quality since the signal-to-noise ratio is likewise increased. The inventive modulation control circuitry includes a microphone 110, audio amplifier 120, splatter filter 130, modulator 150, potentiometer 140, oscillator and transmitter 180, and antenna 190. The audio amplifier 120 further includes an operational amplifier 160 having an input resistor 162 coupled via capacitor 168 to microphone 110, a phase-lag filter 170 coupled to the output of the operational amplifier 160, and a feedback resistor 161 coupled between the filter 170 and the input resistor 162. When driven into amplitude limiting, the phase and amplitude of harmonic signals from the operational amplifier 160 are altered by phase-lag filter 170 to produce a waveform similar to that shown in FIG. 2.

Abstract: A three-party conference circuit provides for three-party conference calls in time-division-multiplex communication systems utilizing pulse-code modulation. The digitized speech signals from a selected group of channels are received from an incoming PCM highway, expanded from PCM coding to linear coding and consecutively stored in groups of three in three registers. Different pairs of the registers are selected by a multiplexer, after which the speech signals from the selected pairs of registers are added to provide a combined speech signal. The combined speech signals are compressed from linear coding to PCM coding and applied to an outgoing PCM highway for transmission to the respective parties. Since the speech signals are combined and retransmitted essentially within the same frame, time delay distortion of the audio signals is minimized.