Abstract: The phase of a data signal relative to a reference clock signal is approximated relatively accurately using only relatively coarse increments of phase shift between trial version of a sampling clock signal (derived from the reference clock signal). Information about which amounts of progressively greater phase shift in the sampling clock signal cause loss of alignment between a training pattern and training data in the data signal can be used for such purposes as identifying the amount of phase of shift of the reference clock signal that will be best for use in sampling the data signal during normal (post-training) operation.

Abstract: A technique of decoding a biphase signal comprises sampling the biphase signal to obtain phase sample values and sampling the biphase signal to obtain magnitude sample values. A first digital signal is derived from the phase sample values and associated bit combinations are formed from the first digital signal. A decision is made whether the bit combination is an erroneous bit combination, and a probability check is performed to obtain probability values that decide which parts of the erroneous bit combination are true and which are false. A corrected bit combination is generated from the obtained probability values, and a second digital signal is generated whose data states are formed from the valid bit combination and, in the presence of an erroneous bit combination, from the corrected bit combination.

Abstract: A method and apparatus reliably encode and decode information over a communication system. The method includes transforming two coefficients into two pairs of random variables, one random variable in each pair having substantially equal energy as one random variable in the other pair. The method further includes quantizing each of the pairs of random variables and entropy coding each quantized random variable separately creating an encoded bitstreams. The encoded bitstreams are received by a decoder which first determines which channels of the communication system are working. The encoded bitstream is entropy decoded, inversed quantized and inversed transformed. An inverse transform performs three different transformations depending upon which channels are working, i.e., whether the first, second or both channels are working.

Abstract: In a training operation for optimizing a multiplication coefficient for each tap of an FIR equalizer equalizing a read signal read from a recording medium, as a restricted coefficient updating vector applied for updating the multiplication coefficient for each tap of an FIR filter, a vector is utilized which is obtained by projecting, onto a plane perpendicular to a predetermined restricting conditioning vector, a coefficient updating vector determined based on an equalizer error between the output of the FIR equalizer and a reproduction output determined therefrom and a delayed input value for each tap of the FIR equalizer.

Abstract: An electrical isolation barrier for use in a Data Access Arrangement uses a high frequency (HF) transformer 24 to provide isolation. An input signal, which may be analog or digital, is connected to a modulator. The analog output of the modulator is connected to the input of the HF transformer. The output of the HF transformer is connected to the input of a demodulator. Simple amplitude modulation can be used in the modulator to modulate the input signal to the frequency range of operation of the HF transformer. A simple low pass filter may be incorporated in the demodulator to remove harmonic distortion caused by the HF transformer. The output signal of the demodulator is substantially the same as input signal.

Abstract: A method and system that communicates adaptive transmit-side filter updates between a receiver and transmitter inserts additional versions of control codes into a back channel for encoding updates. Since the control codes are required in the back channel, no additional bandwidth of the back channel is used to communicate the updates.

Abstract: A method of decoding data includes receiving a symbol and determining a data rate that was used to encode the symbol. A set of correlator output signals are generated based on a first mode when a first data rate was used to encode the symbol and based on a second mode when a second data rate was used to encode the symbol. A maximum-valued signal in one of the set of correlator output signals is identified. The maximum-valued signal in one of the set of correlator output signals is modulated.

Abstract: An algorithm for bit synchronization in a frequency shift keying (FSK) receiver. In the algorithm, a training sequence is received from a transmitter. The training sequence has a plurality of bits. A starting point of a next bit received by the FSK receiver after the training sequence is determined according to peak values of the bits of the training sequence.

Abstract: A signal is predistorted by producing a set of sample values, each of at least a subset of which is dependent on (i) at least one of a plurality of past time spaced input samples and (ii) a current time spaced input sample, and independent of any other time spaced input sample, and combining the sample values to produce the predistorted signal. Predistortion circuitry for generating the predistorted signal may be implemented using multiple predistortion core circuits, with each of the predistortion core circuits receiving a data input and an index input associated with a particular input sample and generating a corresponding data output. The data outputs of the predistortion core circuits correspond generally to sample values. The predistortion circuitry may also include at least one memory finite impulse response (FIR) filter which processes one or more input samples in conjunction with the production of the sample values.

Abstract: Techniques and instrumentalities to improve ISI and ICI cancellation in reception of modulated symbols by selectively decoding subsymbols of such modulated symbol before they can be completely decided or perceived as well as use of decoded symbol/subsymbol information in the feedback equalization process are disclosed. In particular, a decoder and corresponding method are disclosed which includes a feedback equalizer capable of receiving a modulated signal including a symbol defined by a first number of chips, along with a subsymbol processor to generate a subsymbol waveform upon receipt of a second number, less than the first number, of chips of such symbol and provide the subsymbol waveform to the feedback equalizer in order to equalize the modulated signal using the subsymbol waveform.

Abstract: A probability estimating apparatus and method for peak-to-peak clock skews for testing the clock skews among a plurality of clock signals distributed by a clock distributing circuit, and for estimating the generation probability of the peak-to-peak value or peak value of the clock skews. The probability estimating apparatus for peak-to-peak values in clock skews includes a clock skew estimator for estimating clock skew sequences among the plurality of clock signals under test and a probability estimator for determining a generation probability of the peak-to-peak values in the clock skews among the plurality of clock signals under test based on the clock skew sequences from the clock skew estimator by applying Rayleigh distribution. The generation probability of the peak-to-peak value is estimated based on RMS values of the clock signals and the Rayleigh distribution.

Abstract: A system and method for obtaining a frequency error estimate representing the difference between a reference frequency and the frequency of a space-time transmit diversity signal is disclosed herein. The method includes taking the correlation of total sums, comprised of partial sums taken in defined first and second intervals, to represent the frequency error as the imaginary component of the correlation function.

Abstract: A clock recovery circuit includes a sampler for sampling a data signal. Logic determines whether a data edge lags or precedes a clock edge which drives the sampler, and provides early and late indications. A filter filters the early and late indications, and a phase controller adjusts the phase of the clock based on the filtered indications. Based on the filtered indications, a frequency estimator estimates the frequency difference between the data and clock, providing an input to the phase controller to further adjust the phase so as to continually correct for the frequency difference.

Abstract: A data communication apparatus and method based on OFDMA are provided. In a first user transmitting unit through which a user transmits user information to a base station in units of first symbol blocks each including M symbols, a first encoder generates a first sub-block composed of Mu user symbols for a u-th user by encoding the user information. A first block repeater repeats the first sub-block Lu times to generate M symbols. A first multiplier multiplies the M symbols by ?u exp(j2?kmu/M) and outputs a u-th user signal. A first cyclic extension symbol inserter inserts a cyclic extension symbol into the u-th user signal and generates a single complete first symbol block. Accordingly, data transmission speed can be freely changed, a very small PAR can be provided, influence of the signal interference is greatly reduced, interference occurring between received blocks due to channels can be prevented, and distortion between channels can be effectively compensated for.

Abstract: In a path search method, all regions of a delay profile subject to peak detection are divided into a plurality of regions, and a control is performed so as to assign a searching frequency to each regions, which is higher the higher is the total peak power of the path existing in the region. A CDMA receiver in which this path search method is implemented has a region data separating section, which separates region data, a peak position detection section, which detects a peak position of each region, a region index calculation section, which establishes and manages the priorities of each region, and a region designating calculation section, which specifies a region for the region data separating section as a region having a high priority.

Abstract: A system for time delay estimation in a discrete time processing system includes a cross correlator that performs cross correlation on a first signal and a second signal, and provides a cross correlated output signals indicative thereof. A lag smoother receives the cross correlated output signals, and provides lag smoothed output signals indicative thereof. A select logic module selects a pre-defined number of signal values from a respective set indicative of the lag smoothed output signals to compute the time delay estimation associated with the first and second signals.

Abstract: A method and system for conserving power in a WLAN receiver is provided by a channel estimator for detecting transmitted errors in a transmitted packet and providing equalization for the detected channel errors; a separate pilot processor for detecting off set errors from the channel estimation and providing off set correction to said equalization for the whole data portion of the packet after the preamble and a control response to the start of each packet for enabling said channel estimator during the preamble and thereafter disabling said channel estimator for the remainder of the packet and storing the estimated value.

Abstract: New version packet data devices support a backwards-compatible signal format. New version devices operate within a first frequency band while old version devices operate within a second frequency band. The first frequency band differs from but overlaps with the second frequency band. The new version devices may operate on a first carrier frequency (within the first frequency band) while old version devices may operate at a second carrier frequency (within the second frequency band). The new version devices and/or the old version devices may also support carrier-less modulations. Preamble, header, and trailer portions of a new version signal include a plurality of spectral copies of a baseband modulated signal. One or more of these spectral copies of the baseband modulated signal is/are indistinguishable from corresponding components of an old version signal. The payload of the new version signal may be formed in the same manner or may be formed in have a wider bandwidth, higher data rate format.

Abstract: There is provided a PN (Pseudorandom Noise) hypothesis moving apparatus and method in a high speed searcher. In the PN hypothesis moving apparatus, a PN sequence generator system has a PN sequence generator for generating a PN sequence and a PN state register for storing information about a PN state. A correlation counter counts the number of correlations, and a comparator receives the output of the correlation counter, a correlation length, and a search speed, compares them, and provides a PN state saving point and a PN state loading point to the PN sequence generator system according to the comparison to change a PN hypothesis.

Abstract: A communication apparatus and method that includes generating a series of successive spread-spectrum signals formed through the concatenation of a direct sequence spread spectrum code with a Doppler Tolerant Polyphase Code (DTPC) is herein disclosed. By transmitting concatenated codes, it is possible to demodulate received sequences that are very long compared to the inverse of the Doppler frequency and/or the local oscillator drift. The method and apparatus may be applied to implement a wireless telecommunication system that efficiently transfers small quantities of data, such as status/telemetry, identification information and/or establishes device location at a low data rate over long distance in challenging radio environments and with low power consumption.