Abstract: An integrated sigma-delta radio frequency (RF) receiver subsystem (200) and method utilizes a multi-mode sigma-delta analog-to-digital converter (215) for providing a single and multi-bit output. A programmable decimation network (221) for reducing the frequency of the in-phase and quadrature bit stream and a programmable formatting network (223) are also used for organizing the in-phase and quadrature components from the decimation network (221) for subsequent signal processing. The invention offers a highly integrated digital/analog RF receiver back-end which incorporates integrated filtering and a smart gain control that is compatible for use with other receiver systems and offering superior performance characteristics.

Abstract: A method, apparatus, and system determine a location of a frequency synchronization signal in a frame of data transmitted from a transmitter and received by a receiver in a communication system including at least one transmitter and at least one receiver. A peak value representing a detected frequency synchronization signal transmitted from the transmitter to the receiver is calculated. A frequency offset between a carrier frequency of the transmitter and a frequency reference of the receiver is estimated, along with a quality factor for the estimated frequency offset. A determination is made whether the peak value is greater than or equal to a peak threshold and whether the quality factor is less than or equal to a quality threshold. When both of the predetermined threshold conditions are met, the peak value, frequency offset, and quality factor are stored.

Abstract: Disclosed is a system and method for signal conditioning and equalization in the time domain, preferably in a discrete multi-tone (DMT) modem. The system preferably includes a processor operating according to operating logic stored on a memory although a dedicated logical circuit may be employed. The operating logic includes logic executing the function of a low pass filter having a predetermined cutoff frequency configured to process a digitized data signal having a first sample rate f0, producing a filtered data signal at a second sample rate f1. The operating logic further includes logic which executes the function of a time domain equalizer, the time domain equalizer being configured to process the filtered signal to shorten the impulse response of the channel while at the same time, the time domain equalizer down-samples the filtered signal from the second sample rate f1, to a third sample rate f2 for further processing in the frequency domain.

Abstract: Methods and systems are provided for synchronization of a mobile terminal to a communication system which provide faster access to the communication system and reduced risk of non-productive battery power consumption. In particular, the methods and systems of the present invention test one candidate carrier from a list of candidate carriers and perform a power profile to obtain an indication of signal strength of the carrier. This signal measurement is then compared to a threshold criteria. If the criteria is satisfied, the mobile terminal attempts synchronization with that carrier and, if successful, establishes a connection with the communication system. If the criteria is not satisfied, another candidate carrier is selected and tested similarly. Furthermore, the methods and systems of the present invention provide for tiered searching for a valid carrier with each level providing an increased likelihood of finding a carrier while, potentially, requiring a greater amount of time to obtain synchronization.

Abstract: A mobile wireless transceiver selects one of multiple nearby base stations to facilitate communication over a wireless network. Each base station transmits a pilot signal that includes a spreading signal transmitted at one of many possible phase offsets. The wireless transceiver selects an initial one of the possible phase offsets of the spreading signal and then correlates a received signal against the spreading signal at consecutive ones of the possible phase offsets. Correlation begins at the selected initial phase offset and continues until a component of the received signal and the spreading signal are aligned, indicating the detection of the pilot signal from one of the base stations.

Abstract: A computer system (12) comprising a first DSL modem (M12) for communicating data packets (MG1, MG2, MG3) with a second DSL modem (M14) after a connection is established between the first DSL modem and the second DSL modem. The data packets are for communication from the first DSL modem to the second DSL modem at a downstream communications rate and for communication from the second DSL modem to the first DSL modem at an upstream communications rate. The computer system further comprises a memory (MEM12) operable to store a computer program (60), where in one embodiment this computer program is an operating system. The computer program is operable to require a data parameter indicating a number of data packets which may be communicated in an instance from the computer program to the first DSL modem for communication to the second DSL modem. Lastly, the computer system further comprises a field (e.g.

Abstract: A recursive decoder for decoding a binary codeword of length N having a first stage, at least one intermediate stage, and a final stage. The first stage including a plurality of decoder groups, each of the groups having a plurality of sets of first and second decoders, each of the first and second decoders having a plurality of inputs and an output, a plurality of adder groups, each of the adders having a first input connected to the output of the first decoder of one of the sets and a second input connected to the output of the second decoder of one of the sets, and an output.

Abstract: A processing system (216) selects (1004) a portion (702-706) of a received signal including an evaluation symbol (702), along with a preceding symbol (704) received immediately before the evaluation symbol, and a following symbol (706) received immediately after the evaluation symbol; and prefixes (1006) to the portion of the received signal a previously estimated symbol (708) received immediately before the portion, thereby producing an evaluation portion (712, 904). The processing system then compares (1008) the evaluation portion with templates equal in length to the evaluation portion and including different combinations of trial symbols and the at least one previously estimated symbol, prefixed to the trial symbols; and estimates (1010) the evaluation symbol to be equal to a trial symbol in one of the templates having a highest correlation with the evaluation portion, the trial symbol having a position matching that of the evaluation symbol in the evaluation portion.

Abstract: A disc storage system servo code detector is disclosed that provides enhanced error correction capabilities during both tracking and seeking by increasing a minimum distance dmin between valid codewords and by increasing a minimum distance {circumflex over ( )}dmin from the signal space between adjacent codewords to the decision boundaries of all other valid codewords. The signal space with respect to the minimum distances is not a limiting aspect of the invention; however, in the preferred embodiment the codewords are selected to maximize the minimum distances in Euclidean space. Thus, the read signal is sampled and equalized according to a partial response spectrum, and maximum likelihood detection is employed to detect the servo codewords in Euclidean space. The code rate is selected according to certain design criteria such as the amount of error correction desired, the data density, and the cost and complexity of the encoder/decoder circuitry.

Abstract: The invention relates to a receiver for a digital transmission system with an incoherent transmission method, which receiver includes an equalizer for forming estimates for a sequence of symbols a[k] transmitted by a transmission channel from received symbols r[k] by means of an impulse response h[k] that describes the transmission properties. For improving the receiving quality in an incoherent transmission method and transmission channels having intersymbol interference, it is proposed that the equalizer performs an incoherent maximum likelihood sequence estimation (MLSE) method to determine the estimates â[k] for the sequence of transmitted symbols a[k]. In channels having intersymbol interference, the incoherent MLSE method provides clearly better results than all the known incoherent receiving methods. As against frequency and phase offset, the incoherent MLSE method is considerably more robust than all the known coherent receiving methods.

Abstract: A peripheral device cable, connected to a peripheral device, integrally incorporates a subscriber link that is a physical line for transmitting subscriber information in synchronization with a highway clock and a control link that is a physical line for transmitting control data in synchronization with the highway clock. A control data converter controls interfacing between the control data transferred over the control link synchronously with the highway clock and control data that a control unit transmits/receives asynchronously with the highway clock. The subscriber link is connected to a switch.

Abstract: A radio receiver apparatus for receiving a spread spectrum signal in which a signal derived through a level detection of a signal demodulated by a correlative demodulator and a signal obtained by extracting a signal component of a synchronous frequency from a reception synchronizing clock are combined to thereby generate a reference signal having a level which changes in accordance with change of the detected signal, and by comparing the detected signal with the reference signal, the received signal is discriminated.

Abstract: A clock control system in a network switching node including an internal reference clock of a low level Stratum and receiving a plurality of high level Stratum clocks (CLOCK 1, CLOCK 2, CLOCK n) from connection lines, one of these high level Stratum clocks being currently used to generate a Master Clock; the device selecting another high level Stratum clock when the clock currently used to generate the Master Clock fails and comprising for each high level Stratum clock, means (12, 16, 20) for phase locking the reference clock on the selected high level Stratum clock and obtaining a plurality of phase locked (PLL) reference clocks (SOURCE 1, SOURCE 2, SOURCE n).

Abstract: The input data to a CDMA transmitter is used to introduce a slight frequency offset to the clock that is used to generate the CDMA code. At the receiver, the frequency-offset CDMA signal proportionately affects the magnitude of output signals from one or more CDMA correlators. A composite signal that is based on the magnitudes of the output signals is compared to a set of predefined threshold levels to provide the demodulated output data.

Abstract: Through crosstalk on lines, interference from current transmission lines or line echoes, the useable signal is superimposed by different interference signals. The task is to find a procedure for reducing interference which, compared to the current state of the art, can be achieved with a smaller amount of computing input and is suited to both the reduction of quasi steady-state and non-steady interference. In this, the interference of a received signal is classified with regards to characteristics in the time range as a click, crackle, rumble or noise interference signal. The time range in which the interference occurs is marked. Depending on the interference type, interference blanking and/or an interpolation of the useable signal and/or a subtraction of the interference signal from the useable signal and/or a regeneration of the useable signal is carried out.

Abstract: A system for providing information on the clock frequency of a data source in a digital receive-transmit system, where the clock frequency value of the data source is sent at a preset rate (FP), comprising a first signal (FS) at a first frequency (FQ1) associated with the data source, a second signal (FT) at a second frequency (FQ2) associated with the transmission system, measuring means for the first frequency (FQ1) of the first signal (FS) against the second frequency (FQ2) of the second signal (FT). According to the present invention the measuring means (CP, CN, CM) operates at a measuring rate (F) higher than the preset rate (FP) and a post-processing means (P) is provided to send a coded signal (U′) to the receiver (R).

Abstract: In a data communication system having a channel with time-varying impairments and further having a transmitter with a precoder, a method and apparatus for updating the precoder coefficients. The method and apparatus is based on the arrangement of a duplicate precoder and correction filter in the receiver, where the correction filter generates incremental coefficients. The incremental coefficients are sent via a back channel to the transmitter and added to the current values of the precoder coefficients. The method and apparatus provide DFE-like performance and do not have the delay problems associated with DFEs.

Abstract: A serial digital data communications receiver with an improved automatic cable equalizer that is less susceptible to jitter and has greater multi-standards capability, and an improved automatic gain control system with a DC restorer that provides optimal edge jitter performance while avoiding the possibility of a latch-up condition at the start of data transmission. The automatic cable equalizer for equalizing signals received over cables of different lengths has multiple stages each having a transfer function of 1+Ki[fi(j)] wherein each of the Ki vary in accordance with a sequential gain control methodology. The AGC system uses the difference between band-pass filtered versions of the amplitudes of the input and output of a DC restorer based on quantized feedback, to regulate the AGC circuit.

Abstract: A signal when transmitting digital transmission signals between a transmitter unit and at least one receiver unit, one signal lead is generally required as a transmission medium for each digital transmission signal. To permit simultaneous transmission of several digital transmission signals through a common signal lead, the digital transmission signals (S11 . . . S10) are totaled with several logical signal levels in the transmitter unit (1) to form a multilevel signal (m). This multilevel signal (m) is transmitted from the transmitter unit (1) to the receiver unit (3) through a signal lead (2). For the purpose of forming digital received signals (S31 . . . S3n) corresponding to the digital transmission signals (S11 . . . S10), the received multilevel signal (m) is compared in the receiver unit (3) with signal thresholds (V1 . . . Vn) located between the logical signal levels of the multilevel signal (m).

Abstract: Methods and apparatuses consistent with the present invention recover a clock signal from a variable bit rate data signal by estimating, in the time domain, the bit rate of the data signal, and based on the estimated variable bit rate, determining a center frequency of a narrow-band filter for extracting the clock signal from the data signal. A clock recovery circuit consistent with the present invention extracts a clock signal from a variable bit rate data signal by estimating a minimum time interval between transitions in the data signal, generating a plurality of pulses that correspond respectively to transitions in the data signal, adjusting the duration of each of the pulses based on the estimated minimum time interval and inputting into a narrow-band filter the adjusted pulses, determining a center frequency of the narrow-band filter based on the estimated minimum time interval, and extracting in the narrow-band filter the clock signal from the adjusted pulses.