Abstract: The present invention relates to multiple modulus conversion (MMC) techniques for mapping data in a pulse code modulation (PCM) modem system. In accordance with the present invention, signal point constellations are arranged to receive the output indices generated by the MMC procedure such that the probability of transmission of higher power codewords is relatively low compared to the probability of transmission of lower power codewords, while maintaining the same or larger minimum distance between signal points. In addition, the present invention provides techniques for obtaining the probability of occurrence for each constellation or signal point associated with a given data communication session and for determining the theoretical average transmit power associated with a given set of signal point constellations and MMC parameters.

Abstract: A switched-capacitor digital-to-analog converter circuit is disclosed. The switched-capacitor digital-to-analog converter circuit includes crossing switches for each capacitor branch, the crossing switches are used to eliminate cross interference between digital-to-analog converter blocks sharing the same reference voltages.

Abstract: Two compensating resistors in a mirror bias circuit coupled to a radio frequency (RF) amplifier are configured such that transistor base-emitter voltages are adjusted to stabilize RF transistor quiescent current for variations in collector voltage, Vcc. For example, when battery power is drained during device use, Vcc decreases. As Vcc decreases, less current is drawn through the compensating resistors, thereby decreasing the voltage drop across the compensating resistors and increasing the transistor base-emitter voltages in the mirror bias circuit and the radio frequency (RF) amplifier. Thus, the tendency of the RF transistor quiescent current to decrease as Vcc decreases is off-set because the compensating resistors cause an increase in the RF transistor base-emitter voltage, thereby increasing quiescent current.

Abstract: Apparatus for positioning a video teleconferencing camera including a base member having a flat metal base portion and a vertically depending metal arm, the base portion and arm being covered with an elastomeric material, the elastomeric material being shaped to form a socket on the arm which receives a ball member extending from in camera body to form a ball-and-socket connection.

Abstract: A method and apparatus for facilitating AC-link communications between a controller and a slow peripheral of a codec is disclosed. In one embodiment, the GPIO_INT bit (i.e. bit 0 in slot 12 in the AC-link's SDATA_IN line) is utilized as an interrupt flag to indicate when data requested by the controller from the slow peripheral is returned and is available to be read by the controller. The GPIO_INT bit can also be used to indicate when a write into the slow peripheral is completed. In this embodiment, a “peripheral ready bit” or a “peripheral ready signal” originated from the slow peripheral is used to set the GPIO_INT bit. Another embodiment is directed to controllers which ignore the GPIO_INT bit as a source of interrupt. To accommodate these controllers, one of the GPIO bits is used to send the value of the “peripheral ready bit” to the controller.

Abstract: A receiver in a communication system is coupled to a transmission channel for receiving communication signals transmitted over a transmission channel. The receiver includes signal receiving electronics for receiving communication signals directed to the receiver. The receiver also includes a controller, responsive to the receipt of a communication signal by the signal receiving electronics, to provide an enunciator enable signal, and a clock signal generator for generating a clock signal. The receiver further includes an enunciator coupled to the clock signal generator, for producing an electronic sound signal. The enunciator includes a volume control module for receiving a first periodic signal and providing a volume control signal. The enunciator also includes a divider for receiving the clock signal and providing a corresponding output signal having a frequency corresponding to the frequency of the clock signal frequency divided by a divider value.

Abstract: A tone predictor may be employed in a modem system to cancel periodic interference components present in a received signal. The tone predictor may be implemented in a receiver arrangement to cancel such periodic interference and to condition a decision error signal utilized to update the adaptive equalizers. The tone predictor may also be implemented in an echo canceler arrangement to cancel such periodic interference and to condition the error signal used to update the echo canceler filter. The tone predictor includes a delay element, configured to decouple the periodic interference component from other noise components, and an adaptive filter structure configured to generate a periodic interference estimate.

Abstract: A distortion removal system for reducing the quantization distortion that results from quantization of a signal by sample-by-sample quantization techniques is disclosed. The distortion removal system uses the signal previously quantized with the sample-by-sample quantization techniques to determine an expected quantization distortion. The expected quantization distortion is determined for each of a plurality of frames of the signal. The expected quantization distortion is removed from each of the frames of the signal.

Abstract: System and method for processing HDTV format video signals have been disclosed. A disclosed embodiment comprises a HDTV timing generator having as inputs a vertical sync and a horizontal sync. The HDTV timing generator outputs a digital HD level signal. The disclosed embodiment further comprises a DAC interface. The DAC interface can include an encoder channel, or more than one encoder channel. The encoder channel can receive a digital HD level signal, a SCART level signal, an NTSC level signal, a PAL level signal, and a SECAM level signal. The encoder channel can further receive a HDTV format data input, a SCART format data input, an NTSC format data input, a PAL format data input, and a SECAM format data input. The output of the DAC interface can be coupled to a DAC which in turn generates an output suitable for display on a monitor.

Abstract: An apparatus for controlling the power level of an output signal from the output of an electronic amplifier. The electronic amplifier has a control signal input for receiving an amplifier control signal and has a power input for receiving current from a power supply. The apparatus comprises an amplifier output power detector, coupled to the output of the amplifier, used for generating a power measurement signal representing the output power of the amplifier. The apparatus contains a current detector arranged to detect the current received by the amplifier from the power supply and to provide a current measurement signal dependent on the amount of current received from the power supply. The apparatus contains a digital signal processor which receives the current measurement signal and provides a reference signal dependant on the current measurement signal.

Abstract: A data reduction and representation method reduces the number of graphic articulation parameters (GAPs) that must be stored or transmitted to animate an object. A number of GAPs are identified that can be interpolated from other GAPs. A directed graph is created which depicts the identities of the “derived” GAPs, the “defining” GAPs from which derived GAPs can be interpolated, and the relationship between them. The GAPs reside at nodes on the graph which are interconnected with directed links that indicate the “parent” to “child” relationships, with each link representing an interpolation function which defines how the derived GAPs are interpolated from the defining GAPs. The graph and interpolation functions are conveyed to a decoder. Frames containing defining GAPs are then sent to the decoder, which performs the interpolations as directed by the graph and using the interpolation functions to reconstruct the derived GAPs.

Abstract: A digital subscriber line communication system does not require the use of a plain old telephone service (POTS) splitter in the resident's home. Digital signal processing techniques are utilized to adapt to varying subscriber line conditions due to POTS telephone equipment. The digital signal processing techniques eliminate the need for a splitter by reducing susceptibility to distortion due to varying subscriber line characteristics. The digital subscriber line modem characterizes the subscriber line under a variety of conditions. The digital subscriber line modem includes a control circuit which performs rapid retrain operation utilizing line characterization information.

Abstract: A speech compression system capable of encoding a speech signal into a bitstream for subsequent decoding to generate synthesized speech is disclosed. The speech compression system optimizes the bandwidth consumed by the bitstream by balancing the desired average bit rate with the perceptual quality of the reconstructed speech. The speech compression system comprises a full-rate codec, a half-rate codec, a quarter-rate codec and an eighth-rate codec. The codecs are selectively activated based on a rate selection. In addition, the full and half-rate codec are selectively activated based on a type classification. Each codec is selectively activated to encode and decode the speech signals at different bit rates emphasizing different aspects of the speech signal to enhance overall quality of the synthesized speech. The overall quality of the system is strongly related to the excitation. In order to enhance the excitation, the system contains a fixed codebook comprising several subcodebooks.

Abstract: Computers commonly connect to remote computers and networks using the telephone lines. A telephone line is composed of a positive line (Ring) and a negative line (Tip). Because there is no guarantee, in general, which line on a two-conductor telephone jack will be positive and which will be negative, diode bridges are often used to assure correct polarity of devices coupled to the telephone lines. Commonly computers connect to telephone lines using modems, which plug into the computer. The modems often contain two jacks, one to connect the modem to the telephone line, the other to provide an outlet for a telephone. Commonly both jacks are wired in parallel. Embodiments of the inventions provide for wiring the telephone jacks in opposite polarity, or switching polarity via jumpers. A method is provided to detect a telephone plug in the jack of incorrect polarity. A user may be instructed in advance or prompted to switch jacks or jumpers if necessary and the need for the diode bridge is eliminated.

Abstract: The present invention relates to a method and apparatus that uses cyclic redundancy check (CRC) bits to detect errors and correct particular four-bit error patterns in an information burst. The present invention is particularly suited for relatively simple systems that use differential encoding and either differential or coherent demodulation with no error correction capabilities, such as the Personal Handy Phone System (PHS), DECT, PACS and some digital cordless phones systems. The apparatus also adjusts its error-correction capability to accommodate different types of information bursts and channel qualities. The present invention may be used in a number of wireless, digital communication systems.

Abstract: A multi-task structure for a software modem including a plurality of self-contained executable entities. The executable entities include at least a controller and a data pump with the controller operating as an interface between an operating system driver and the data pump when signals are passed from the operating system driver to the data pump. In addition, the data pump includes at least a scheduler and a hardware driver, the scheduler interacting with additional self-contained executable entities and enabling the data pump to operate using one or more individual ones of the additional self-contained executable entities according to the signals passed from the controller to the data pump.

Abstract: An apparatus and method for power management of embedded electronic subsystems. A power management control circuit for managing power to an embedded subsystem includes a subsystem power node connected to a first section of the embedded electronic subsystem and a bias voltage node connected to a second section of the embedded electronic subsystem. A power switch is connected between a power supply and the subsystem power node. By separating the power subsystem node from the bias voltage node, power can be removed from the subsystem, while still providing the necessary bias voltage to the electronic static discharge (ESD) diodes. This prevents the voltages applied to the system bus by the subsystem from causing bus contention or system bus lock-ups. A power removal and restoration procedure is also disclosed.

Abstract: An iterative system for performing carrier phase tracking of symbols using a serial turbo decoder. Estimates of a buffered block of symbols are provided by a serial turbo decoder. Optionally, reliability metrics for the estimates are provided as well. Responsive to this information, a tracking loop module determines derotation phases for each of the symbols in the buffer. A symbol derotator derotates each of the buffered symbols in the block by its corresponding derotation phase. The derotated symbols are stored back in the buffer. The process may repeat itself for a prescribed number of iterations, after which the serial turbo decoder provides estimates of the underlying source bits.

Abstract: A method and apparatus for sensing audio frequency-pressure modulation of the moisture content of the atmosphere caused by a moisture-laden audio source, such as a live human voice, is disclosed. A first light emitter is provided to generate a first light beam. An audio source that emits moisture, and the environment, modulate the first light beam to generate a first modulated light beam. A first detector is provided to detect and demodulate the first modulated light beam to recover an uncompensated audio signal. A second light emitter is provided to generate a second light beam. The second light beam is modulated by the environment and not by the audio source to produce a second modulated light beam. A second detector is provided to detect and demodulate the second modulated light beam to recover the signal component caused by environmental conditions.

Abstract: A temperature stable bias circuit for a radio frequency (RF) power amplifier uses current deletion and current supplement techniques to maintain the bias, or reference current of the RF power amplifier at a stable level regardless of the temperature that the power amplifier is operating. When temperature increases, the current deletion circuitry reduces the bias current supplied to the power transistor. When the temperature decreases, the current supplement circuitry increases the bias current supplied to the power transistor. This bias circuitry allows the output of the RF power amplifier to remain constant. The current deletion and current supplement circuitry can be fabricated using the same processing technology as the power amplifier and can be easily integrated into the power amplifier device packaging.