Abstract: In a communication system network that comprises a plurality of communication systems and a processing multiplexer, the processing multiplexer comprises a processing module, a buffer module, a multiplexer module, and a buffer address module. The buffer module temporarily stores processed audio information, which is produced by the processing module, in one of several sections. The processed audio information is stored in section of the buffer module based on which signal destination it is for. If the processed audio information is destined for a signal destination that is assigned to a slot in the first distination interface bus, the processed audio information is stored in the first buffer location. When the processed audio information is placed onto the destination interface buses, it done so in a round robin fashion such that the communication system may operate in a real time frame.

Abstract: A frequency agile, dielectrically loaded bandpass filter is disclosed in which capacitive layers on the top surface of the filter are selectively switched to ground in order to affect a change in the center frequency of the passband response of the filiter. A PIN diode switching network, including a means for biasing the diode, is used to effectively place the capacitive layers in parallel with the quarter-wavelength transmission line resonators contained within the block of the filter.

Abstract: A simulcast broadcast uses digital signal processing techniques to scale pulse coded modulation samples of a signal for broadcast. Samples are adjusted to fully utilize all quantization levels representable by an 8-bit word. Time delay is adjustable using digital techniques by writing and reading data into and out of a RAM. Signal amplitude is adjustable by multiplying samples by a numeric factor. A computer can be used to adjust processing, delay and amplification of the digital signal processor.

Abstract: A data transfer network for computers is disclosed which combines characteristics of both multi-port memory devices and local area networks. Each computer is coupled to the network via a data terminal. The terminal permits the network to appear to the computers as random access memory. Data written into this RAM by the computers is formatted by the terminals into serial data packets, which are shifted around a serially connected ring or loop of the terminals. The loop connected terminals form the network.

Abstract: An electrostatically energized and integrable relay is disclosed that has dimensions that permit closure and maintenance of a contact between electrodes using electrostatic forces exclusively. The physical dimensions are such that it could be formed using integrated circuit fabrication techniques. Small spacing between the electrodes of the relay permit the device to be usable in an integrated form, perhaps on an integrated circuit substrate.

Abstract: In a multipoint data communications system used with analog communications channels that may insert undesirable frequency offsets in a modem carrier frequency, a slave modem that adjusts its transmit carrier frequency compensates for the offset influenced communications channel. A central modem device does not have to train up to slightly offset frequencies when the communications channel is effectively removing the offset added by a slave modem at its transmitter site.

Abstract: An adjustable slew rate amplifier in the input stage of an amplifier circuit helps reduce off-channel frequency splatter. In instances where test sequences are input to an amplifier circuit that are used to measure maximum permissible input levels to the amplifier, inclusion of a low slew rate amplifier in the input loop further prevents the production of off-channel frequency splatter caused even by the input test sequence. The adjustable slew rate amplifier is run at full slew rate, providing full-bandwidth amplification, during periods of normal circuit operation.

Abstract: The RF data communication band pass filter is a fixed device that filters both RF multi-level data signals and binary-level data signals. The RF data communication band pass filter comprises a low pass filtering means having a corner frequency of approximately 2900 Hertz and as high pass filtering means of approximately 340 Hertz. By using precision components the overall group delay envelope is such that both multi-level RF data signals and binary-level RF data signals are adequately filtered without substantial harmonic distortion or spectral distortion. In addition, the communication band pass filter meets the strictest of international RF data communication requirements.

Abstract: Reusing radio frequency specta in a trunked radio system by establishing small cell trunked radio systems within a large cell trunked radio system wherein low power radio transmission occurs permits multiple small cell trunked radio systems in geographically separate locatiosn to use a limited number of radio resources simultaneously, increasing usage of a finite number of communication resources. As used in cellular telephone systems, very low power trunked radio systems separated from each other can reuse the same frequency without interfering with each other or interfering with a large cell trunked radio system license holder.

Abstract: A speech operated noise attenuation device (SONAD) includes circuitry to measure the noise level in an audio channel. The output of the noise measurement circuitry provides a control signal to an audio attenuator which varies the intersyllable attenuation of the background noise according to the noise level present in the audio.

Abstract: A method and arrangement for providing damping of undesired modes of piezoelectric vibrators is disclosed that eliminates the tedious and often inaccurate methods of known mass-loading techniques. Instead, the arrangement relies on physically altering a controlled amount of the piezoelectric material located at a predetermined point to effect the selective damping needed to minimize the undesired responses and to minimally interfere with the desired mode of operation.

Abstract: In a conventional quartz crystal resonator, a sacrificial quartz layer attached to the mounting posts and between the active, vibrating quartz layer and the package base reduces mechanical stresses on the active quartz layer caused by thermal expansion coefficient differences. The intermediate quartz layer is a sacrificial layer which acts to maintain the spacing of mounting posts.

Abstract: A PLZT based shutter system reduces flare produced by reflective surfaces normally associated with PLZT based and other SLR shutter systems by eliminating a diffraction mirror and using highly reflective electrodes directly on the PLZT element to function both as the reflective mirror and as the electrodes to produce the E field in the PLZT element. The invention has an improved performance by reducing flare and has a reduced parts count improving its manufacturability and reliability.

Abstract: An improved method of statistically determining the presence of noise on an FM communications channel permits digital signal processing techniques to more reliably squelch unnecesssary segments of an FM receiver reducing noise and power consumption. Digital samples of an FM signal having real (in-phase) and imaginary (phase quadrature) components representing the real and imaginary components of a phasor rotating about the origin of a Cartesian coordinate system at a rate indicative of a signal on the channel are mathematically operated on. Successive digital samples are multiplied by the complex conjugate of temporally adjacent samples producing a new stream of phasors representative of the phase change between samples. The phase changes between samples are processed to produce a number that indicates the probability of the channel having noise present.

Abstract: A method of filtering an AC signal using a piezoelectric beam is provided. A piezoelectric film is formed on a mechanical support and a portion of the piezoelectric film forms a beam which extends beyond the mechanical support so that a cavity is formed underneath the beam, and the beam is free to vibrate in the cavity at a resonant frequency when an acoustic wave is propagated in the piezoelectric layer.A depletion region is formed under a Schottky contact which serves as a drive electrode. An unfiltered AC signal is coupled to the drive electrode thereby establishing an acoustic wave when the unfiltered AC signal comprises a component at the resonant frequency. Surface charge on the piezoelectric film resulting from vibration of the beam allows the resonant frequency component of the unfiltered AC signal to pass through the depletion region. Alternatively, the resonant frequency component can be passed by a tunnel current through the cavity.

Abstract: An amplifier circuit uses a microprocessor to count occurrences of the output stage going into saturation to decide when to control input levels to the amplifier. When the output amplifier stage saturates too frequently, the microprocessor controls a scaling line that effectively attenuates input levels to the amplifier, eliminating saturation levels. When the output stage saturates too infrequently, input levels to the amplifier are increased.

Abstract: A rotatable contactless RF signal coupler, which couples RF signals between an antenna and an RF signal processor in a portable radio, along with an antenna capable of operating in two modes is described herein. Specifically, the signal coupler includes a transformer that is primarily located within the hinge formed by the housing of the radio and a rotatable flip portion. Substantially constant inductive coupling is maintained in the coupler regardless of rotation. The antenna is capable of operating in a narrow band and a wide band mode to afford antenna operation through varied conditions.

Abstract: A direct conversion FM receiver that comprises a quadrature mixer, an A to D converter, a digital demodulator, a digital phase lock loop, and frequency offset setting means is disclosed. The quadrature mixer receives FM signals and mixes them with a local oscillator signal to produce an analog in-phase baseband signal and an analog quadrature baseband signal. The analog in-phase baseband signal and the analog quadrature baseband signal are converted into digital signals by the A to D converter. The digitally converted baseband and quadrature signals are digitally demodulated and filtered by the digital demodulator such that modulation information is produced. The modulation information is used, at least in part, to control the phase lock loop means.

Abstract: A planar microstrip inductor formed from a spiral shaped conductive path of material on a dielectric uses a bifilar spiral by which both the connection nodes of the inductor can be brought out to the edge of the substrate. The bifilar winding by which both connection nodes are available from the exterior of the spiral shape includes the use of a jumper wire to connect the inner node of the inductor to a circuit.