Abstract: A data interface for CMOS imagers is disclosed that can be either a single-ended interface or a differential interface. The single-ended interface provides compatibility with many existing external devices. Further providing a differential interface allows a lower noise and a lower power interface for external devices that can support a differential signal. The combined single-ended and differential signal interface does not increase the number of pins required for a single-ended only interface. The data transfer width is set to the word width, which allows a fixed timing relationship between the clock edge and data transfer in both single-ended and differential modes. In single-ended mode, the data is transferred once per clock, but in the differential mode, the data is transferred twice per clock, once on each clock edge. This fixed timing relationship eliminates the need for and cost of explicit bit synchronization.

Abstract: A speech encoder that analyzes and classifies each frame of speech as being periodic-like speech or non-periodic like speech where the speech encoder performs a different gain quantization process depending if the speech is periodic or not. If the speech is periodic, the improved speech encoder obtains the pitch gains from the unquantized weighted speech signal and performs a pre- vector quantization of the adaptive codebook gain Gp for each subframe of the frame before subframe processing begins and a closed-loop delayed decision vector quantization of the fixed codebook gain GC. If the frame of speech is non-periodic, the speech encoder may use any known method of gain quantization.

Abstract: An exemplary multi-channel speech processor comprises a controller capable of interfacing with a plurality of channels, and at least one signal processing unit (SPU) coupled to the controller, where the multi-channel speech processor has a maximum execution time for processing all frames, one channel at a time, by processing a single frame from each of the plurality of channels. The signal processing unit encodes each of the single frames from each of the plurality of channels, one channel at a time, to generate encoded frames until the maximum execution time elapses or is about to elapse. The controller also transmits a pre-determined frame for each of the plurality of channels not processed during the encoding step, due to the maximum execution time elapsing or being about to elapse, such that the predetermined frame causes a decoder which receives the predetermined frame to generate a frame erase frame.

Abstract: A communication system for communication of data packets or cells associated with a packet or cell switched network is disclosed herein. The system includes a plurality of ports and a switching segmentation and reassembly device. The switching segmentation and reassembly device routes data packets or cells to and from the ports and the at least one destination. The switching segmentation and reassembly device further switches data packets or cells between ports. The switching segmentation and reassembly device switches cells from cell ports to packet ports by reassembling cells into packets and manipulation of information. The switching segmentation and reassembly device switches packets from packet ports to cell ports by segmenting packets into cells and manipulation of header information.

Abstract: A multi-rate speech codec supports a plurality of encoding bit rate modes by adaptively selecting encoding bit rate modes to match communication channel restrictions. In higher bit rate encoding modes, an accurate representation of speech through CELP (code excited linear prediction) and other associated modeling parameters are generated for higher quality decoding and reproduction. For each bit rate mode selected, pluralities of fixed or innovation subcodebooks are selected for use in generating innovation vectors. The speech coder distinguishes various voice signals as a function of their voice content. For example, a Voice Activity Detection (VAD) algorithm selects an appropriate coding scheme depending on whether the speech signal comprises active or inactive speech. The encoder may consider varying characteristics of the speech signal including sharpness, a delay correlation, a zero-crossing rate, and a residual energy.

Abstract: An apparatus and method for detecting the presence of a display device at the output of a video driver utilizes a terminating resistance connected between the output of the video driver and a ground level. A current is driven by the video driver, resulting in a voltage level at the output. A comparator compares the resultant voltage to a reference voltage signal to determine whether the resultant voltage is above or below a predefined threshold. The threshold is chosen as lying between an anticipated resultant voltage for a video driver having a display device connected thereto and an anticipated resultant voltage for a video driver without a display device connected thereto.

Abstract: A cable modem having a programmable media access controller (MAC). A single cable modem device includes all necessary MAC functions. The invention allows programmable MAC functions to support evolving standards (e.g., DOCSIS) without requiring expensive hardware upgrades. Bifurcated microprocessor architecture, in which first processing circuitry is programmed to implement MAC functionality for processing information flowing to and from cable media interface circuitry, and second embedded processor core or host system processor provides operating system functionality are used. Alternatively, separate processor cores provide MAC functionality for downstream and upstream data paths, respectively. Cable media interface circuitry, and other peripheral circuitry, are coupled to a peripheral bus that is linked by a bridge circuit to a system bus. The processing circuitry MAC is communicatively coupled to the system bus.

Abstract: A system that provides packaging for a surface acoustic wave filter in such a way that the surface acoustic wave filter is capable of integration with a number of additional electronic devices on an integrated substrate. The surface acoustic wave filter is mounted in a “flip chip” configuration that enables the surface of the surface acoustic wave filter to be protected from a molding compound during and after the encapsulation of the surface acoustic wave filter and other circuitry contained on the integrated substrate. The manner in which the surface acoustic wave filter is packaged provides a great reduction in cost and occupied real estate on the integrated substrate, in that, the surface acoustic wave filter is mounted in such as way as not to require conventionally used ceramic packaging that encases the surface acoustic wave filter. An air gap is preserved between the surface acoustic wave filter side of the surface acoustic wave filter and the integrated substrate on which it is mounted.

Abstract: A MAP decoding system in which one or more backward engines operate to calculate backward state probabilities for sub-blocks within a sliding window stored in a memory. One or more forward engines calculate forward state probabilities for a sub-block in the same order as the encoded symbols for the sub-block are stored. Calculation of the forward state probabilities for a sub-block are deferred until the backward state probabilities for the sub-block have been calculated. Responsive to the calculation of the forward and backward state probabilities, the one or more forward engines calculate and release soft outputs for a sub-block in synchronization with the calculation of the forward state probabilities. The sliding window may be moved throughout the block, and the foregoing process repeated until soft outputs for the entire block have been released.

Abstract: Iterative decoder employing multiple external code error checks to lower the error floor and/or improve decoding performance. Data block redundancy, sometimes via a cyclic redundancy check (CRC) or Reed Solomon (RS) code, enables enhanced iterative decoding performance. Improved decoding performance is achieved during interim iterations before the final iteration. A correctly decoded CRC block, indicating a decoded segment is correct with a high degree of certainty, assigns a very high confidence level to the bits in this segment and is fed back to inner and/or outer decoders (with interleaving, when appropriate) for improved iterative decoding. High confidence bits may be scattered throughout inner decoded frames to influence other bit decisions in subsequent iterations.

Abstract: A circuit and method is disclosed for self trimming in frequency acquisition and clock recovery. The circuit can be simplified as having a VCO in communication with three loops including a trimming loop, a frequency loop and a phase loop. The trimming loop includes a ramp generator for supplying a steady increase of bias current to the VCO causing the frequency of the VCO to increase. At each step, the averaged output of the frequency detector is measured by a comparator. A decision circuit included in the trimming loop registers the output of the comparator in digital format. The trimming loop continues until the decision circuit detects a long string of positives followed by a long string of negatives and at this point, the trimming loop is shut off and the frequency loop is in operation. The frequency loop drives the VCO frequency to within a small difference of the incoming data frequency. The phase loop cleans up the data and locks the phase.

Abstract: The invention describes a non-real time fax transmission and reception system, in which fax emulation or “spoofer” software resides between application software and a fax/modem device. The fax/modem device may be comprised of hardware or software in any proportion. The fax spoofer software uses a fax/modem emulator to interface between requesting application software to have the application software believe that it is communicating with an actual, as opposed to virtual, fax/modem device. The emulator creates a class 1 or class 2 fax/modem session of the transmission request, which may be transmitted to a fax/modem device at a later point in time. Additionally, the fax spoofer software may be used to buffer, queue, or process incoming facsimiles, which can either be stored in the local memory of a fax/modem device or in the memory portion of the fax spoofer software.

Abstract: A full duplex speaker-phone that performs adaptive filtering to provide increased loop stability between users of the speaker-phone. The invention employs a sliding filter that performs adaptive frequency dependent attenuation of the speech signals within a speaker-phone. By detecting the mode of operation of the speaker-phone in real time, the speaker-phone performs adaptive filtering to ensure a high perceptual quality for the users of the speaker-phone. The sliding filtering is performed using a sliding low pass filter (LPF) in certain embodiments of the invention. Perceptually, the speaker-phone does not surrender the appearance of a full duplex speaker-phone from the perspective of the users. In addition, by performing frequency dependent filtering of the speech signals, the speaker-phone offers improved stability in the speaker-phone loop and reduces residual echoes significantly over conventional technology employed in speaker-phones.

Abstract: A system for carrier phase tracking of symbols. In an embodiment employing a feedback structure, a symbol derotator pre-rotates a symbol by a derotation phase. A symbol and reliability estimation engine provides, responsive to the pre-rotated symbol, an estimate of the symbol and a reliability metric for the estimate. A tracking loop module determines a residual between the pre-rotated symbol and the symbol estimate, weights the residual by the reliability metric for the estimate, and determines a phase offset estimate responsive to the weighted residual. An accumulator then determines a next derotation phase responsive to the phase offset estimate. In an embodiment employing a feedforward structure, a symbol and reliability estimation engine provides an estimate of a symbol and a reliability metric for the estimate.

Abstract: There is provided system and method for communication over a network, which includes a first gateway and a second gateway capable of communicating with each other using a packet protocol. Each gateway is capable of communicating with a local communication device, such as a modem device, over a telephone line. In modem relay mode, each gateway is capable of detecting V.8bis signals from the communication devices, blocking such V.8bis signals, and switching to modem relay mode in response to such detection. In modem pass through mode, each gateway is capable of detecting V.8bis signals from the communication devices and switching to modem pass through mode in response to such detection.

Abstract: A quick startup procedure for a modem system utilizes known characteristics of a previously established communication channel to reduce the initialization period associated with subsequent connections over the same channel. In response to the establishment of a call, the modem devices determine whether the quick connect protocol is supported. If so, then the called modem transmits a modified answer tone to the calling modem. The calling modem analyzes the signal received in response to the modified answer tone to determine whether characteristics of the current channel are similar to stored characteristics associated with a previous connection over the same channel. If a channel “match” is found, then the modem devices carry out a quick initialization routine that eliminates, abbreviates, or modifies a number of procedures or protocols that are carried out in conventional modem startup processes.

Abstract: A video quantizer provides for performing quantization adaptively in accordance with perceptual masking characteristics of the human visual system. In a preferred MPEG encoder-IC, a block-based activity quantization modification or “activity-modification” is formed from the combined correlation of block-energy and edge analyses. A luminance-sensitivity modification is then formed and correlated with the activity modification to form an intermediate modification. A nominal-quantization modification is further formed and correlated with the intermediate modification, which is then limited and correlated with a nominal quantization value to form a base modification. Next, a positional-sensitivity modification is formed as a perimeter offset, which offset is correlated with the base modification to form a modified quantization value, and which modified quantization value is then rounded and returned to a rate controller.

Abstract: A continuous-tone facsimile mechanism supports a transmission rate control mode to control the transmission rate of a continuous-tone image (e.g., a color image) based on the data rate between the transmitter and receiver. The transmission rate is controlled by scaling the original quantization values based on the data rate producing scaled quantization values which are then used to compress the image. The scaled quantization values are transmitted along with the compressed continuous-tone image. Via a rate control mode, a continuous-tone facsimile device with this transmission rate control technique can allow a user to specify whether the transmission rate control is activated or deactivated.

Abstract: A fast train protocol for use by a high-speed point of sale (POS) modem is disclosed. In one aspect, the fast train protocol may include he following exemplary steps: receiving an instruction to connect to a remote modem; transmitting a tonal signal to the remote modem for a pre-determined period of time in response to receiving the instruction, where the tonal signal identifies the POS modem as being capable of supporting the fast train protocol; receiving an S signal from the remote modem in response to transmitting the tonal signal; receiving an S\ signal from the remote modem following receiving the S signal; receiving one or more remote PP signals from the remote modem following receiving the S\ signal; and receiving a remote parameter sequence from the remote modem following receiving the one or more remote PP signals.

Abstract: A pulse code modulation modem system is configured to transmit data from a first modem to a second modem over the public switched telephone network (PSTN). The PSTN employs robbed bit signaling (RBS) such that symbols affected by RBS arrive at the second modem in a periodic manner based on a period of six symbols. The modem system is configured such that signal segments are formatted and transmitted with six symbols per segment. After obtaining symbol synchronization, the second modem initializes a modulo-6 symbol counter such that the zero count corresponds to the first symbol of each received signal segment. Those symbols affected by RBS are identified and analyzed to determine optimized signal point constellations that may be used to compensate for the RBS on a symbol-by-symbol basis during subsequent encoding and decoding. Upon a loss of synchronization, the second modem resets its modulo-6 counter in response to the detection of the first symbol in a subsequent signal segment.