Abstract: An electroacoustic loudspeaker apparatus is provided including a piezoelectric driver element, the opposed major surfaces of which are acoustically coupled into first and second resonant structures. The first resonant structure exhibits a resonant frequency less than the resonant frequency of the driver and the second resonant structure exhibits a resonant frequency greater than the resonant frequency of the driver thus resulting in a broadened or enhanced frequency response.

Abstract: An integratable amplifier circuit with logarithmic electronic gain control capability. The circuit is suitable for audio applications and permit logarithmic control of volume with an external potentiometer without need to send the audio signal through control lines. In addition, the temperature coefficient of the gain is maintained at a very low level over a wide gain range.

Abstract: A radio pager decoder including a register which is incremented when a page is received and a visual indicator which displays a count of the number of received pages. Pages may also be selectively retrieved from memory.

Abstract: A mounting structure is provided for electro-optical display character elements. The mounting structure includes first and second electrically insulative substrates, each substrate of which includes an aperture. The aperture of the second substrate is somewhat smaller than the aperture of the first substrate such that when the apertures are aligned, the second substrate exhibits a lip under the aperture of the first structure. A display character element including electrodes on the opposed surfaces thereof is situated in the aperture of the first substrate. Electrode elements on the lower surface of the display character element are electrically coupled to corresponding electrode elements situated on the upper surface of the second substrate extending onto the lip. An interconnecting element electrically couples electrodes on the upper surface of the character element to corresponding electrodes on the upper surface of the first substrate.

Abstract: An apparatus and a method are provided for determining when a moving body assumes a motionless state. A rate of turn sensor is attached to the moving body. A signal indicating that the body is substantially motionless is generated when the rate of turn signal generated by the sensor is substantially constant.

Abstract: Digital method and apparatus for generation of a digital data stream with the bit transitions shaped to reduce splatter, and minimize droop and overshoot in a radio communications system utilizing digital coded squelch. A codeword digital data stream, in digitized form, is shaped so that the bit transitions have the form of a portion of a sine waveform and then is applied to a D/A converter. A simple filter follows the D/A converter to attenuate sampling noise.

Abstract: CVSD modulation is detected by applying a digital signal containing CVSD information to a digital filter that is in the CVSD loop that includes a syllabic filter and a rule circuit. The digital filter includes voltage-operated switches that switch one of two voltages to a resistor network and thereby combine multiplication and digital filtering. The output of the digital filter is the output of the circuit.

Abstract: A frequency synthesized transceiver capable of tuning to a plurality of communication channels is disclosed. The transceiver includes a receiver section and a transmitter section which are coupled to the synthesizer which generates the appropriate injection signals to achieve tuning. The frequency synthesizer includes a multiposition switch which accesses various addressable memory locations in a programmable read-only memory where the appropriate divisors are stored to cause tuning of the synthesizer to the appropriate communication channel. A zone selector switch enables grouping and easy retrievability of channels. The divisors are supplied to a single synchronous binary swallow counter which works in conjunction with a dual modulus prescaler to monitor the frequency output of the voltage controlled oscillator. A programmable divider coupled to a reference oscillator source is compared with the output of the synchronous counter in a digital and analog phase detector.

Abstract: Clock recovery in a received stream of digital data is effected by generating a high-speed clock pulse that is applied to a programmable divider to produce a recovered clock pulse. Comparison of the phase of the recovered clock pulse with that of a received signal causes accumulation of fast or slow counts that increase or decrease the division of the programmable divider to restore synchronism. The accumulated count is reduced for rapid recovery when the two signals are unsynchronized.

Abstract: A pager or other selectively-addressed electronic device powered by a small power cell operates in four different modes and at two power levels, depending on signals received and a timing sequence. The device can stay active continuously, be activated at intervals or remain in a powered-down state. The address code assigned to a particular device would be transmitted at a predetermined time interval following a sync signal, thus the device can be powered-down until the approximate time period in which its address code could be transmitted. The system provides increased channel efficiency since information codes are superimposed on actual address codes, and there is no dead time in a channel while there are address codes waiting to be transmitted. The system is particularly well adapted to time multiplexing.

Abstract: A frequency synthesized transceiver capable of tuning to a plurality of communication channels is disclosed. The transceiver includes a receiver section and a transmitter section which are coupled to the synthesizer which generates the appropriate injection signals to achieve tuning. The frequency synthesizer includes a multiposition switch which accesses various addressable memory locations in a programmable read-only memory where the appropriate divisors are stored to cause tuning of the synthesizer to the appropriate communication channel. A zone selector switch enables grouping and easy retrievability of channels. The synthesizer includes a priority channel monitoring system utilizing a channel element for rapid sampling. The divisors are supplied to a single synchronous binary swallow counter which works in conjunction with a dual modulus prescaler to monitor the frequency output of the voltage controlled oscillator.

Abstract: A method of captivating a substrate within a holder for photolithographic processing is shown. A substrate is placed within the aperture of a holder and is sandwiched into place by laminating it with layers of dry film photopolymer resist. Portions of the photopolymer resist are polymerized. Unpolymerized portions are washed away leaving retaining tabs of polymerized resist which hold the substrate within the holder for an etching or plating process.

Abstract: An improved housing arrangement is disclosed for a small, hand-held battery powered portable device which includes an associated battery compartment with integral battery door accessible from the side of the housing. The battery door and compartment are intercoupled by a non-destructive, breakaway hinge device which permits separation therebetween when the door is pivoted outwardly from the top beyond a set predetermined limit. It may be reattached simply and conveniently by a press fit. A latch mechanism is included integral with the surface of the battery door which may be operated by hand without special tools to latch and unlatch the door.

Abstract: An interference rejection apparatus is provided which samples the Loran C signal at selected pulse tracking reference points. The Loran C samples are separated into even and odd groups by appropriate summing-weighting circuitry. The even pulse and odd pulse waveforms thus produced are analyzed to determine the presence of an interfering signal which corrupts either of the off or even pulse groups. Upon detection of interference with either the even or odd Loran C samples, strobe dropping is employed to reject the affected group of samples.

Abstract: An improved low-voltage, low-current, high-noise immunity I.sup.2 L interface is disclosed for control of associated I.sup.2 L logic circuitry, which interface does not require the inclusion of the heretofore conventional low-pass RC filter found in prior devices. As a result, considerable chip area previously occupied by such low-pass filters is now saved. Moreover, by isolating a portion of the interface switching circuitry from all other portions of the I.sup.2 L circuitry a substantial reduction in source current is effected. This objective is accomplished by fabricating at least one of the I.sup.2 L gates and its injector transistor in a separate epitaxial tub.

Abstract: A single molded plastic part forms the actuator, the latching beam and the retainer for holding the latch mechanism in position, and also provides detented open and closed positions. The latch mechanism can be used with the door or closure for an opening in a housing, such as the battery door for a small portable electronic device. The one-part latch has an actuating button on one side of the door which cooperates with resilient retainer tabs to hold the latch in movable engagement with the door. An integral latching beam may extend on the other side of the door and be movable to a position to latch the door. Indentations on the beam, or on another part of the latch, can cooperate with a detent cam to hold the latch mechanism in released or open, and latched or closed positions. The latch mechanism can be either slidably or rotatably movable for the latching operation.

Abstract: A quadrature detector includes a driving circuit for applying a frequency modulated square-wave to one input of a gating circuit and to the input of a phase-shift network whose output is connected directly to the other input of the gating circuit. A tracking DC bias voltage is introduced at the input of the gating circuit which is coupled to the output of the phase-shift network, and the level of this DC voltage is selected so that the gating circuit switches on the zero-crossings of the sinusoid outputted by the phase-shift network. This scheme eliminates the need for a limiter used in conventional quadrature detectors that operate from low-voltage power supplies such as a one volt battery.

Abstract: An improved socket assembly is disclosed which is especially suited for use in printed circuitry with dense configuration of components in limited areas of surface. The socket is mounted on an associated printed circuit board and allows horizontal insertion of vertically stacked keyed components, from either side of the socket assembly. The socket assembly further includes a non-metallic insert, consisting of two mating halves containing a plurality of wire contacts of equal geometric diameters, capable of accommodating component leads of differing geometric configurations (i.e., square, rectangular, triangular, round, etc.) which provide pressure to the component lead thereby holding the component in place. The insert is unaffected by the molten solder or flux used during the manufacturing process and prevents entry of contaminating material into the interior of the socket assembly during the soldering process thereby eliminating electrical shorting problems occasionally caused by the soldering process.

Abstract: A helical cavity resonator having a grounded shield, a hollow coil form and associated quarter wavelength wire coil. A non-ferrous conductive slug can be adjusted to variable positions inside the hollow coil form. Placement of the slug in a region proximate to the inside of the wire coil tunes the cavity resonator in a predominately inductive manner. Changing the slug position in the bore so that it is proximate to the shield top and removed from the inside of the wire coil tunes the cavity resonator in a predominately capacitive manner. By utilizing both inductive and capacitive tuning a helical cavity resonator with a wide tuning range is realized while maintaining a simple, inexpensive construction.