Abstract: A microphone assembly is adaptable to righthand or lefthand operation by having a reversibly positionable pushbutton. The microphone housing has two oppositely located apertures for receiving the pushbutton. The aperture not used is covered with a part of a reversibly positionable shroud. The pushbutton is a lever which pivots about a pin and activates a spring loaded leaf spring switch, the switch being operable from two opposite directions by the reversibly positionable pushbutton lever.

Abstract: A sampling filter-detector receives input signals of different frequencies and provides an output, or detect signal, only when the input frequency has a predetermined value essentially equal to the drive frequency of the sampling circuit. The input signal is coupled through a series of solid state switches, or multipliers, to storage, or sampling, capacitors, the average voltages of which are coupled through voltage peak and valley followers to a comparator which supplies an output or detect signal only when the difference between the positive and negative voltage inputs to the comparator is greater than a certain value. This occurs when the input frequency is within the detector bandwidth. A threshold voltage of a desired value may be placed in the circuit coupling the peak follower and the positive input of the comparator. The solid state switches are turned on and off by pulses from digital logic means such that the switches are on 120.degree.

Abstract: An electro-optic display device using an electro-optic plate operating in the transverse bias mode selectively transmits light. A first conductor having an aperture is formed on one side of the plate and is overlaid with an insulating layer. A second conductor is formed over the insulating layer and crosses over the first conductor. The second conductor also has apertures generally aligned with the apertures in the first conductor and separated by a portion of the conductor extending to the surface of the electro-optic plate. An arrangement of first and second conductors may be disposed to have the apertures form an addressable dot-matrix display.

Abstract: A three position switch which selectively interconnects isolated conductors on a printed circuit board is disclosed. In one embodiment, pressure sensitive conductive elastomer pads, disposed in the switch, are brought into contact with isolated conductors on a substrate. A sliding switch actuator, having a cam surface with indentations, is then used to selectively apply pressure to the conductive elastomer pads and thereby selectively connect the isolated printed circuit board conductors. In another embodiment, a three position switch is shown including a plurality of conductive pads, flexibly attached to a switch casing, which are positioned above printed circuit board isolated conductors and then selectively flexed downward into contact with the printed circuit board conductors by moving a sliding actuator arm having a cam surface.

Abstract: An improved lightweight, stiff member for use as a speaker diaphram is formed from a porous layer of high stiffness fibers. The fibers are randomly oriented, spaced-apart, and crossover each other at given points to form a porous layer with a given thickness. The fibers are bonded to each other at the given crossover points. A gastight film is also bonded to the layer of fibers thereby providing a gastight member having high flexural stiffness.A method for making a lightweight, stiff member by the application of a dilute solution of an epoxy resin and a solvent to a porous layer of randomly oriented, spaced-apart, high stiffness fibers. The solvent is removed, leaving a thin layer of epoxy resin on the fibers. The porous layer of fibers and a gastight overlying sheet are pneumatically formed into a predetermined configuration.

Abstract: An amplitude modulated transmitter includes an audio amplifier which, via a radio frequency (RF) power supply modulator, modulates an RF amplifier and carrier. Fluctuations in the direct current DC bias to the RF amp, such as are common in mobile applications, vary the modulation index of the transmitted signal.To minimize DC bias affects on the modulation index, the invention contemplates an audio compressor which senses both audio signal level and DC bias level and, in response thereto, controls audio signal compression to maintain the desired percent modulation. Compression is effected by changing the bias on a semiconductor device which, in turn, attenuates audio signals at the input of a fixed gain audio amplifier. A feedback path around the audio amplifier senses both DC voltage and audio signal level and produces an appropriate control signal to bias the semiconductor device, thereby altering audio compression.

Abstract: There is disclosed an antenna including an accurately formed whip member and an accurately formed loading coil one end of which is connected to one end of the whip member and the other end of which is connected to a single connector. The length of the whip member and its diameter and any associated metallic connector are selected to give a predeterminedly accurate capacitive value. The loading coil has a predeterminedly accurate inductive value such that the loading coil and whip member have a net accurate inductive value which is connected to a predeterminedly accurate capacitor for matching the impedance of the antenna to the conductor, coaxial cable for example, from the transmitter. The capacitor, a single stub connector, the end of the coaxial cable and the necessary connections are epoxy encapsulated in a base housing.The connector at the end of the loading coil is attached to the single stub connector in the base to provide the only connection necessary for the antenna to become operative.

Abstract: A hermetically sealed mobile antenna base containing all of the components necessary to proper antenna functioning with the exception of the loading coil and antenna whip for vehicular application is disclosed. A single connector screw extends outwardly from the base casting and is insulated therefrom by an insulating washer. Interiorly of the base casting an impedance matching capacitor is disposed with one lead connected to the connector screw and the other lead connected to ground. The coaxial cable is led into the base casting and has its center conductor connected to the connecting screw and its ground conductor connected to the casting. The complete interior of the base casting is encapsulated with an epoxy compound. Spaced apart connection ears extend from one side of the base casting providing for attachment of the antenna base to the vehicle.

Abstract: The antenna of a transceiver couples through a low pass filter to the input port of a high pass filter network. The high pass network is designed to reflect a very high impedance to its input port when its output port is at ground potential. The transmitter portion of the transceiver couples to the input port of the network with the receiver coupling to the network output port. A semiconductor diode couples from the output port to ground potential.In the receive mode the combination low pass and high pass filters couple received signals in the desired frequency band to the input of the receiver. Upon activation to the transmit mode the diode is forward biased whereby the network output port is taken to ground potential. In this mode the filter network effectively isolates the receiver from the transmitter.

Abstract: A rate one-half random error convolutional coding system corrects the theoretical limit of one error out of four successive bits. An information bit stream is processed through the system encoder which is comprised of a two-bit shift register and a modulo-2 adder. The encoder generates a parity bit formed by the modulo-2 summing of successive pairs of information bits, and produces a convolved transmission bit stream. The system decoder is the replica of the encoder in combination with a two-bit syndrome register, an AND gate, complementary feedback circuitry, and an output modulo-2 adder.Overall system performance is the simplest, fastest, and highest performing of all such systems known to date.

Abstract: An improved circuit for producing a signal indicative of an input signal floor level is disclosed for use in determining the noise level of an audio signal in a receiver voting system. An input audio signal which contains noise is amplified by variable gain amplifier circuitry consisting of a constant gain amplifier and a variable attenuator. Detector circuitry then develops a signal which is indicative of the noise level, this signal substantially corresponding to the minimum peak magnitude of the amplified input audio signal. During pauses between audio tones in the input audio signal, this minimum signal magnitude coincides the residual background noise level of the input audio signal. Control circuitry couples the noise level indicative signal to the variable attenuator and constitutes a negative feedback loop for inversely and nonlinearly varying the amplification of the input signal in response to the magnitude of the noise indicative signal.

Abstract: A zero-insertion-withdrawal force connector is disclosed. The contact fingers thereof are arranged in two series at right angles to each other. By a single movement in one direction of an operating lever two cam, or actuating, motions are produced for causing, essentially simultaneous, engagement of two series of contact fingers.

Abstract: A piezoelectric disc having opposed major surfaces with electrodes affixed thereto bonded in generally parallel overlying relationship to a piezoelectrically inactive acoustic radiation member by means of an elastomeric interlayer, which elastomeric material is characterized by having a shear modulus which varies directly with the frequency of stresses applied to said elastomeric material.

Abstract: The output from a peak detector of a conventional radio receiver includes a recovered audio signal and a DC level. The disclosed noise limiter processes the detector output through both low pass and high pass filters. The low pass filter produces a DC signal representative of both the detector DC level and the recovered audio signal level. The high pass filter passes only the recovered audio signal. A semiconductor diode connects between the filter outputs, and the output of the noise limiter. For peak detector levels at, or below the 100% modulation level the diode is forward biased and passes the audio signal to the noise limiter output for further receiver processing. Peak detector levels exceeding 100% modulation, such as noise, reverse bias the diode whereby the audio signal is blocked from subsequent receiver stages.

Abstract: An R. F. power transistor device is disclosed wherein the common lead inductance may be controlled to any desired value from zero to relatively high values.The transistor device includes an insulating member of beryllium oxide to one side of which there may be bonded the usual metal heat sink. On the other side of the beryllium oxide member there are metallized areas to which the input and output ground conductors are bonded, the input lead is bonded, the output lead is bonded and the collector of the transistor chip is bonded. One plate of an MOS capacitor is bonded to the input ground lead. In the case of grounded emitter applications, short, small wires are connected from the emitter areas of the transistor in each direction to the input ground leads and the output ground leads respectively. The base areas of the transistor are connected by short, small wire leads to the other plate areas of the MOS capacitor and to the input lead.

Abstract: In a transmitter designed for periods of extended use, means for sensing the ambient temperature in which the transmitter would operate if activated and adjusting the initial output power of the transmitter so as to reduce the initial output power of the transmitter to maximize or increase the power output above that obtainable using existing protective techniques over an extended period.