Abstract: An improved liquid crystal display cell (34) comprising two substrates (108, 124) spaced apart and containing a quantity of liquid crystal mixture (18) therebetween, in which the substrates have facing surfaces (108', 124') coated with a continuous, electrically conducting material (38, 36), is provided with an array of spacer pads (40) at a pre-selected distance apart from each other, having a pre-selected height to maintain a given spacing between the substrates, and having a pre-selected cross-section that avoids substantial interference with the display properties of the liquid crystal display cell.

Abstract: An apparatus for generating an on-screen television program guide. The apparatus generates a program guide including program source information and program event information for a plurality of program sources. The apparatus also generates and displays icons adjacent the program event information that represent a match between content information for a program event and selection criteria entered by a viewer.

Abstract: An efficient and power-saving method of converting serial in-phase (I) and quadrature-phase (Q) symbols at the IS-54 standard symbol rate, to time-aligned IQ pairs at the CDPD standard symbol rate. A FIFO buffer stores the serial in-phase (I) and quadrature-phase (Q) symbols at the IS-54 standard symbol rate. A DSP performs CDPD demodulation by reading time-aligned IQ pairs directly from the FIFO buffer, even though the FIFO buffer contains serial in-phase (I) and quadrature-phase (Q) symbols at the IS-54 standard symbol rate. This is accomplished by performing a rate conversion method between the DSP pointer and the FIFO buffer. The rate conversion combines, symbol rate conversion, sample timing alignment, and sign corrections in one calculation, resulting in an efficient method of generating the desired time-aligned IQ pairs at the CDPD symbol rate. A look-up table is used for several of the variables in the rate conversion calculation.

Abstract: A cellular system has base stations in which diversity transmission is controllably employed to improve voice communications as needed. Normal signal transmission is employed in each voice channel unless it is detected that quality has dropped to a point where diversity transmission is needed to enhance the quality. When it is detected that a voice channel needs diversity transmission, a diversity (delayed) signal is automatically transmitted for that channel over an independent path. A common diversity transmitter is employed for all channels, whereas individual transmitters are employed for the normally transmitted signals in the respective voice channels.

Abstract: A method of detecting double talk in an echo canceller is provided. The method includes determining far end, near end and echo signal cancelled power, determining the presence of near end, maybe near end and far end speech, and controlling an echo suppressor and filter coefficient updates in an echo canceller.

Abstract: A circuit and method for depuncturing data in the receiver circuitry of a digital communications system. The depuncturing circuit includes a multiplexer circuit that receives a punctured stream of data and a delayed version of the punctured stream of data. The multiplexer circuit generates a multiplexer output which can be either a bit from the punctured stream of data, or a bit from the delayed version of the punctured stream of data. A control circuit is coupled to the multiplexer circuit to select which multiplexer input appears on the multiplexer output. The control circuit selects the multiplexer output according to a depuncture pattern that reproduces the pre-punctured order of the data stream. The control circuit may be a counter coupled to a decoder which is coupled to the multiplexer. The decoder may be specially designed to decode the predetermined depuncture pattern and rate, and the counter controls the decoder's movement through the depuncture pattern and rate.

Abstract: A remote ground terminal transmitter for transmitting a modulated data signal having a constant envelope amplitude. The remote ground terminal transmitter comprises a source of data signals, a modulator for providing a carrier signal, receiving a data signal from the source of data signals, and modulating the carrier signal with the received data signal so as to produce a constant envelope minimum shift key modulation signal. The transmitter further comprises a power amplifier which operates in the saturation mode to amplify the modulated carrier signal produced by the modulator to the desired power level.

Abstract: The present invention relates to a device and a method for communicating in a mobile communication system. The method provides a carrier signal having a plurality of frames. Each frame has a plurality of time slots, and each time slot comprises a plurality of transmission bits. A group of time slots are assigned to a communication channel. A traffic burst signal having a plurality of traffic symbols is transmitted over the communication channel by transmitting a first preamble over one of the assigned time slots, and transmitting a second preamble and at least one of the traffic symbols over at least one of the other assigned time slots. The second preamble occupies fewer transmission bits than the first preamble.

Abstract: A remote ground terminal for generating and transmitting a modulated data signal to a satellite. The remote ground terminal the remote ground terminal includes an indoor unit for generating a modulated data signal having an envelope of constant amplitude, and an outdoor unit including a transmitter module operative to receive the modulated data signal and to frequency multiply and amplify the modulated data signal so as to produce a modulated carrier signal having an envelope of constant amplitude. The transmitter module includes an active FET multiplier operative to frequency multiply the modulated data signal to the frequency of the modulated carrier signal, and a power amplifier operated in the saturation mode, which amplifies the modulated carrier signal to the desired power level. The components constituting the transmitter module are formed on a single integrated circuit.

Abstract: An apparatus and method for use in receiving radio frequency (RF) signals having varied frequency bands from a n-sector base station antenna, and converting the RF signals to intermediate frequency (IF) signals for allocation to all available receiver radio channels. By employing a combiner and power splitter/divider, the IF signals from the converters in each sector of the receiver can be accessed by every receiver radio channel. Accordingly, remote communications users placing calls in high traffic sectors will have access to all available radio communications channels.

Abstract: The present invention provides a multi-mode CELP encoding and decoding method and device for digitized speech signals providing improvements over prior art codecs and coding methods by selectively utilizes backward prediction for the short-term predictor parameters and fixed codebook gain of a speech signal. In order to achieve these improvements, the present invention provides a coding method comprising the steps of classifying a segment of the digitized speech signal as one of a plurality of predetermined modes, determining a set of unquantized line spectral frequencies to represent the short term predictor parameters for that segment, and quantizing the determined set of unquantized line spectral frequencies using a mode-specific combination of scalar quantization and vector quantization, which utilizes backward prediction for modes with voiced speech signals.

Abstract: A method of loading propellant into a spacecraft that comprises storing and transferring propellant in a portable propellant loading tank, temperature conditioning and helium saturating the propellant in the propellant loading tank, transferring the loading tank to a launch site, coupling the loading tank to the propellant storage tank, and pressurizing the portable propellant loading tank to transfer the propellant to the propellant storage tank in the spacecraft. The method may further comprise weighing the propellant loading tank during propellant transfer, venting the propellant storage tank in the spacecraft to a receiver tank, and weighing the receiver tank during propellant transfer. The amount of propellant transferred to the propellant storage tank is equal to the difference between the measured weights of the respective loading and storage tanks.

Abstract: A Supervisory Audio Tone (SAT) based Carrier-to-Interference (C/I) ratio measurement system uses the SAT tone to determine the desired signal to undesired interferers so that an intelligent hand-off decision can be made in a digital cellular communication system. The measurement is implemented by digital signal processors which allows additional signal processing and subsequently noise rejection over analog techniques. The received level of the desired SAT as well as the received levels of the SATs for the co-channel interferers is detected. The ratio of the desired SAT level to the sum of the undesired SAT levels provides the C/I measurement. By monitoring this C/I measurement, the base station can determine when to make a hand-off. This SAT based C/I measurement system also aids in the selection of a candidate cell to which the subscriber is handed-off. Surveillance receivers in the candidate cells make SAT based C/I measurements as well as Received Signal Strength Indication (RSSI) measurements.

Abstract: A method and apparatus for generating and navigating an on-screen program guide comprising current and future scheduling information for a plurality of different program sources. The method comprises the steps of entering a date and a time which defines a reference time for the on-screen program guide, and generating the on-screen program guide containing scheduling information for the plurality of different program sources including the user-entered reference time.

Abstract: A radar tracking system 100 adapted for use with existing radar tracking systems. The inventive system includes a radar target detection system 106, 108 for detecting radar targets in clutter using magnitude and angular position information obtained from return signals. A tracking algorithm 104 is used to track and update the positions of said targets with respect to the position of the radar system. The tracking algorithm includes a true target angle estimator 110 for maintaining accurate target angle information when the target is clutter and when the target is out of clutter. The tracking algorithm maintains accurate target distance information when the target is in clutter and when the target is out of clutter. In a specific embodiment, accurate distance information is maintained in a track file 122 where the amplitudes of return signals are stored once a target is detected by the detection system 100.

Abstract: Apparatus that performs automatic gain control (AGC) for an electronic imaging camera, especially in outdoor surveillance applications. A fiber optic link is used to collect ambient light and couple this light onto a small portion of a light sensing array of the camera. A reference voltage produced by the light sensing array in response to the light from the fiber is used by AGC circuits in the camera to control the integration time of light sensing elements of the array, the gain of the camera's video amplifier, and lens aperture, if necessary. These camera gain controls are adjusted to maintain the reference voltage derived from the light provided by the fiber optic link to be within a predefined range as the ambient light level varies due to weather conditions and time of day. Methods of providing automatic gain control correction are also disclosed.

Abstract: A method for estimating high frequency components of a compressed image normally lost during a data compression stage and an encoder and a decoder for carrying out same. The image is compressed to obtain unquantized and quantized frequency domain coefficients. An inverse quantization is performed on the quantized coefficients to obtain lossy frequency domain coefficients. Loss characteristics of the high frequency components are then determined based on the unquantized frequency domain coefficients and the lossy frequency domain coefficients according to one of several methods. Finally, the loss characteristics are coded to obtain encoded loss data corresponding to the lost high frequency components.

Abstract: A bit rate Codebook Excited Linear Predictor (CELP) communication system which includes a transmitter that organizes a signal containing speech into frames of 40 millisecond duration, and classifies each frame as one of three modes: voiced and stationary, unvoiced or transient, and background noise.

Abstract: A preferred embodiment provides a radio port controller in a wireless personal communications system including a first interface module in communication with a radio port, a second interface in communication with a digital switch, and at least one switching transcoder module in communication with the first and second interface modules. A further preferred embodiment provides that the switching transcoder module includes a digital signal processor. The radio port controller preferably has a communication backplane including a plurality of slots, and each slot is preferably adapted to selectively receive either a T1 card interfacing to a T1 line or an E1 card interfacing to an E1 line.

Abstract: An electronic document delivery system and method in which a broadcast center periodically sends a "catalog" of available documents to a receiving computer, thereby allowing a user to browse through the available documents without having to access the broadcast center. The documents are transmitted as packets, and the packets are decrypted as soon as they are received, eliminating the need to store both an encrypted and an decrypted version of the documents at the receiving computer. The receiving computer periodically receives information allowing it to decrypt received documents and to encrypt billing information for the receiving computer. The invention is not limited to text-only documents and can receive all types of documents, such as software, images, text, and full-motion video.