Abstract: In one embodiment, a demapper uses two hybrid-QPSK constellations to demap pairs of equalized data symbols recovered from 16-QAM, DCM OFDM symbols, wherein the equalized data symbols in a pair correspond to the same four-bit group. A first hybrid-QPSK constellation is generated by combining the real components of both 16-QAM mapping constellations onto one coordinate plane. The demapper generates a first set of two decision variables by combining the real components of each equalized data symbol in a pair to correspond to the first hybrid-QPSK coordinate plane. A log-likelihood ratio is then calculated for both decision variables in the set to determine likelihood estimates for the first and second bits of the four-bit group. This process is repeated for the imaginary components of each corresponding pair of equalized data symbols to generate likelihood estimates for the third and fourth bits of the four-bit group.

Abstract: In one embodiment, a mobile communication device is adapted to provide geography-enhanced blog search results. In response to a blog-search query entered by a user, the mobile communication device is adapted to determine a current geographical location for the mobile communication device and a home location for the user. The mobile communication device is further adapted to provide the current location and home location information along with the search query parameters to a search engine. The search engine is adapted to provide results corresponding to blog posts that satisfy the parameters of the search query, wherein the search results are ranked based on at least one of (a) the geographic proximity of a blog post subject to the current location and (b) the geographic proximity of a blog post author's home location to the user's home location.

Abstract: A method and system for modeling and calibrating duty cycle distortion (DCD) of a Serializer and Deserializer (SerDes) device, including first generating a clock DCD signal. Once the clock DCD signal is generated, it is calibrating based upon results obtained from a filtering process of the clock DCD signal. Once the clock DCD signal is calibrated, a data DCD signal is generated and calibrated based upon results obtained from a filtering process of the data DCD signal.

Abstract: A method and apparatus are disclosed for reducing noise, such as external noise, cross-talk and echo, in an unbalanced channel. A cross-talk canceller is disclosed that uses a multi-dimensional finite impulse response filter to process both the differential, d, and common-mode, c, components of a received signal. Recovery of the differential mode component of the received signal is improved by reducing the contribution of the common mode component. The common mode component of a received signal may be expressed, for example, as the average of two voltages or two current signals. The differential and common mode components of the received signal are equalized. The disclosed multi-dimensional cross-talk canceller reduces external noise; near-end crosstalk resulting from differential and common mode components on one twisted pair interfering with another twisted pair; and echo crosstalk resulting from differential and common mode cross-talk components on the same twisted pair.

Abstract: Methods and apparatus are provided for evaluating the eye margin of a communications device using a data eye monitor. The quality of a data eye associated with a signal is evaluated by sampling the signal for a plurality of different phases; evaluating the samples to evaluate one or more of a height and width of the data eye; and determining whether the one or more of the height and width satisfy one or more predefined criteria. One or more parameters of the communications device can optionally be adjusted if the communications device does not satisfy the one or more predefined criteria. The communications device can optionally be assigned to a quality category based on the evaluation. A phase offset between a first clock signal used to sample the signal and one or more clocks used to sample data is reduced.

Abstract: A memory circuit includes a plurality of memory cells and a plurality of bit lines and row lines connected to the memory cells for accessing selected memory cells. The memory circuit includes a programmable voltage source adapted for connection to at least one bit line and operative to precharge the bit line to a prescribed voltage level prior to accessing a selected one of the memory cells coupled to the bit line. A control circuit coupled to the bit line is operative to oppose discharge of the bit line during at least a portion of a given memory read cycle. A tracking circuit connected to the control circuit is operative to control a delay in activation of the control circuit and/or a duration of time the control circuit is active as a function of a parameter affecting signal development time of a data signal on the bit line.

Abstract: Provided is a method for separating a semiconductor wafer into individual semiconductor dies. The method for separating the semiconductor wafer, among other steps, may include implanting an impurity into regions of a semiconductor wafer proximate junctions where semiconductor dies join one another, the impurity configured to disrupt bonds in the semiconductor wafer proximate the junctions and lead to weakened regions. The method for separating the semiconductor wafer may further include separating the semiconductor wafer having the impurity into individual semiconductor dies along the weakened regions.

Abstract: Apparatus and method to allow retrieval of voice messages deleted from the voice message memory of a voice messaging system. A voice messaging system such as a telephone answering device includes a deleted voice message memory for storing voice messages deleted from the voice message memory. The deleted voice messages stored in the deleted voice message memory are retrievable by the user for review subject to rules for permanent deletion of the deleted voice messages (e.g., after a period of time, when the deleted voice message memory approaches capacity, periodically, etc.).

Abstract: Various approaches to recover data are described. An one example, an encoded data stream is processed in a first channel decoder producing a channel decoder output. The channel decoder output and the encoded data stream are processed in an error compensation unit to compensate the channel decoder output for low frequency noise and produce an error compensated data stream. The error compensated data stream is processed in a second channel decoder to produce a recovered data stream, wherein the recovered data stream has a reduction in the number of errors as compared to the encoded data stream. Systems to iteratively recover data from an encoded data stream are also described.

Abstract: Various embodiments of the present invention provide systems and methods for media defect detection. For example, a data receiving system is disclosed that includes a data signal provided from a medium that may include a defective portion. An absolute value circuit receives the data signal and provides an output corresponding to an absolute value of the data signal. The output corresponding to the absolute value of the data signal is input to a filter that filters it and provides a filtered output. In some cases, the filter is a digital filter operable to integrate the absolute value of the data signal. A comparator receives the output from the filter and compares it with a threshold value. The result of the comparison indicates a defect status of the medium.

Abstract: A method and apparatus are disclosed for canceling cross-talk in a frequency-division multiplexed communication system. The disclosed frequency-division multiplexed communication system employs multiple carriers having overlapping channels and provides an improved cross-talk cancellation mechanism to address the resulting interference. Bandwidth compression is achieved using n level amplitude modulation in each frequency band. An FDM receiver is also disclosed that decomposes the received broadband signal into each of its respective frequency bands and returns the signal to basehand in the analog domain. Analog requirements are relaxed by removing cross-talk from adjacent R-F channels, from image bands, and minimizing the performance degradation caused by In-phase and Quadrature-phase (I/Q) phase and gain mismatches in modulators and demodulators. The disclosed transmitter or receiver (or both) can be fabricated on a single integrated circuit.

Abstract: Methods and apparatus are provided for blind transport format detection using Discontinuous Transmission (DTX) detection. According to one aspect of the invention, the transport format that was used to transmit information is determined by identifying a transition between a Discontinuous Transmission segment and a data segment included in the transmitted information; and determining the transport format based on a location of the transition of the Discontinuous Transmission segment. A cyclic redundancy check can optionally be performed for a plurality of possible transport formats, and then the step of identifying a transition can be limited to those transport formats having a valid cyclic redundancy check.

Abstract: Executed when a channel input (e.g., LDPC) codeword is written to a storage medium, a write-verification method (i) compares the channel input codeword to the written codeword, (ii) identifies any erroneous too bits, and (iii) stores the erroneous-bit indices to a record in a table. At some later time, the written codeword is read and sent to a decoder. If the decoder fails with a near codeword, a write-error recovery process searches the table and retrieves the erroneous-bit information. The codeword bits at those indices are adjusted, and the modified codeword is submitted to further processing.

Abstract: Methods and apparatus are provided for determining receiver filter coefficients for a plurality of phases. One or more coefficients for a receiver filter are determined by determining a first coefficient for a first phase of a data eye; and determining a second coefficient for a second phase of the data eye. The receiver filter may be, for example, a decision-feedback equalizer. The first and second coefficients may be determined by performing an LMS adaptation of decision-feedback equalization coefficients. In another embodiment, the first and second coefficients may be determined by obtaining eye opening metrics from a data eye monitor corresponding to each of the respective first phase and the second phase; and determining the respective first and second coefficients based on the eye opening metrics. The first and second phases can correspond to odd and even phases.

Abstract: A method for increasing a voltage tolerance of a MOS device having a first capacitance value associated therewith is provided. The method includes the steps of: connecting at least a first capacitor in series with the MOS device, the first capacitor having a first capacitance value associated therewith, the first capacitor having a first terminal coupled to a gate of the MOS device and a second terminal adapted to receive a first signal; and adjusting a ratio of the first capacitance value and a second capacitance value associated with the MOS device such that a second signal present at the gate of the MOS device will be an attenuated version of the first signal. An amount of attenuation of the first signal is a function of the ratio of the first and second capacitance values.

Abstract: The invention, in one aspect, provides a semiconductor device that comprises a collector located in a semiconductor substrate and an isolation region located under the collector, wherein a peak dopant concentration of the isolation region is separated from a peak dopant concentration of the collector that ranges from about 0.9 microns to about 2.0 microns.

Abstract: In one embodiment, a demapper uses two hybrid-QPSK constellations to demap pairs of equalized data symbols recovered from 16-QAM, DCM OFDM symbols, wherein the equalized data symbols in a pair correspond to the same four-bit group. A first hybrid-QPSK constellation is generated by combining the real components of both 16-QAM mapping constellations onto one coordinate plane. The demapper generates a first set of two decision variables by combining the real components of each equalized data symbol in a pair to correspond to the first hybrid-QPSK coordinate plane. A log-likelihood ratio is then calculated for both decision variables in the set to determine likelihood estimates for the first and second bits of the four-bit group. This process is repeated for the imaginary components of each corresponding pair of equalized data symbols to generate likelihood estimates for the third and fourth bits of the four-bit group.

Abstract: Various embodiments of the present invention provide systems and methods for determining fly height. For example, a system for fly height determination is disclosed that includes a head assembly disposed in relation to a storage medium, a write channel, and a read circuit. The read circuit is operable to receive information from both the head assembly and the write channel. A frequency determination circuit is included that is operable to receive a first signal from the read circuit corresponding to information received from the write channel and to provide a first fundamental frequency and a first higher order frequency based on the first signal, and the frequency determination circuit is operable to receive a second signal from the read circuit corresponding to information received from the head assembly channel and to provide a second fundamental frequency and a second higher order frequency based on the second signal.

Abstract: In one embodiment, a receiver has a reference generator and a main equalizer. The reference generator equalizes a received signal using one or more pilot reference signals. Then, the reference generator decodes one or more predetermined data channels of the equalized signal, makes hard decisions on the data of each decoded channel, and regenerates the original coding sequence of each decoded channel. The main equalizer uses each re-encoded channel as an additional reference signal along with one or more pilot signals to equalize a time-delayed version of the received signal. In alternative embodiments, the receiver might also have a step-size generator which selects optimum step sizes from a look-up table based on the number of re-encoded channels and the power of those channels. The step size is then used by the main equalizer along with the re-encoded channels to equalize the time-delayed received signal.

Abstract: A packet delay variation simulation system has a packet generator, a packet delay variation generator, and a packet delay analyzer to analyze delayed packets. The packet delay variation generator has multiple delay distribution modules that use both a deterministic delay process and a statistical delay process packet for determining a packet's delay. The packet delay variation generator may utilize different probability density functions to describe various portions of measured packet data. That is, measured packet delay information is analyzed and information from this analysis is used to construct a total delay model for a network. The delay may include a pre-determined deterministic delay offset as well as one or more variable statistical delay offsets.