Abstract: An equalizer (200A) comprises a feedforward filter (210), wherein the feedforward filter includes a plurality of feedforward filter taps, coefficients are associated with the plurality of feedforward filter taps, and values of all of the coefficients associated with the plurality of feedforward filter taps are dynamically determined. In some embodiments, the equalizer also comprises a decision feedback equalizer (216).

Abstract: A method of synchronizing a feedforward filter that receives a signal resulting from the transmission of a series of symbols through a channel, wherein the series of symbols includes a predetermined sequence of symbols includes the step of developing a plurality of samples from the received symbols, wherein a sequence of samples corresponds to the predetermined sequence of symbols. The method further includes the steps of estimating a channel impulse response from the plurality of samples, wherein the channel impulse response estimate is represented by a plurality of correlation values, identifying a maximum correlation value from the plurality of correlation values, defining a window relative to the maximum correlation value, calculating a characteristic of the correlation values within the window, and synchronizing the feedforward filter in accordance with the characteristic.

Abstract: A method of controlling sampling frequency of a sampling device (40), where the sampling device (40) generates samples (62) in response to the receipt of a signal (20) resulting from a transmission of a series of symbols through a channel, the method including the steps of estimating (46) a channel impulse response of the channel from the samples, calculating a characteristic of the channel impulse response estimate, and determining (52) the sampling frequency in accordance with the characteristic.

Abstract: An equalizer for processing blocks of data includes n?1 data shifters, n finite filters, an adder, and a controller. Each of the n?1 data shifters shifts the blocks of data. One of the n finite filters applies a corresponding set of finite filter coefficients to the blocks of data, and each of the other n?1 finite filters applies a set of finite filter coefficients to a corresponding output of the n?1 data shifters. Ghosts of the blocks of data are not eliminated as a result of the application of the n sets of finite filter coefficients corresponding to the n finite filters, and n>2. The adder is arranged to add outputs from the n finite filters. The controller is arranged to control the sets of finite filter coefficients corresponding to the n finite filters so that the addition performed by the adder substantially eliminates the ghosts.

Abstract: A data-and-pilot directed frequency-and-phase lock loop for an offset-QAM modulated signal having a pilot signal comprising a pilot acquisition loop and a pair of data-directed acquisition loops. The pilot is extracted from the main signal by a pilot filter, then used both by the pilot acquisition loop and to remove the pilot from the signal to the data-directed acquisition loops. The outputs of the pilot and the two data-directed acquisition loops are summed and returned to the VCO to complete the feedback loop.

Abstract: An equalizer comprises: an FIR; a trellis decoder coupled to the FIR; a mapper coupled to the trellis decoder; and a decision feedback equalizer coupled to the mapper. The decision feedback equalizer receives the mapped and scaled output of the trellis decoder as input and an error signal is generated by subtracting an output of the decision feedback equalizer from the input to the trellis decoder.

Abstract: An adaptive equalizer comprises a decision device; a decision feedback equalizer coupled to the decision device; an FIR filter coupled to the decision device; and a trellis decoder coupled to the decision device, adapted to provide a reliability output and a decoded output. An error signal is generated by subtracting an output of the decision feedback equalizer from an output of the decision device, the error signal being used to update coefficients of the taps of the FIR filter and the decision feedback equalizer. A magnitude of the change to the coefficients is selected based at least in part the reliability output of the trellis decoder.

Abstract: A digital equalizer comprises a matched filter that, in conjunction with an FIR filter, assures a single peak with substantially greater energy than other peaks caused by ghosts, thereby permitting synchronization even with multiple, arbitrarily strong ghosts caused by strong multipathing, multiple transmitters, or both.

Abstract: A data-directed frequency-and-phase lock loop for an offset-QAM modulated signal comprises a first multiplier that multiplies the signal by the output of a VCO. The output of the first multiplier is phase-shifted by a second multiplier, then convolved by a third multiplier. The output of the third multiplier is split, with each portion being passed through a frequency-shift multiplier and a frequency-and-phase lock loop. The output of the two frequency-and-phase lock loops is summed and returned to the VCO to complete the feedback loop.

Abstract: A data-directed frequency-acquisition loop capable of generating a frequency error having a magnitude and direction from a double sideband suppressed signal comprises a first multiplier that multiplies the signal by the output of a VCO. The output of the first multiplier is convolved by a second multiplier. The I output of the second multiplier passes through a first low-pass filter. The filtered I output and the Q output are then multiplied by a third multiplier. The output of the third multiplier is filtered through a second low-pass filter, amplified, and return to the VCO to complete the feedback loop.

Abstract: An equalizer substantially eliminates a ghost of a received main signal by (i) applying coefficients b (where b may be equal to one) to the received main signal and the ghost in order to modulate the received main signal and the ghost so that the received main signal and the ghost are unequal, (ii) applying coefficients a to the modulated received main signal and ghost in order to substantially eliminate the ghost, and (iii) applying coefficients c as a window function to the substantially ghost-free received main signal in order to remove the modulation imposed on the received main signal by the coefficients b.

Abstract: An equalizer includes n processing paths arranged to process blocks of data. N?1 data shifters are arranged so that each of the n?1 data shifters is in a corresponding one of the n processing paths and so that one of the n processing path has no data shifter. N finite filters are arranged so that each of the n finite filters is in a corresponding one of the n processing paths, and so that each of the n finite filters applies a corresponding set of finite filter coefficients to the blocks of data. Ghosts of the blocks of data are not eliminated as a result of the application of the sets of finite filter coefficients corresponding to the n finite filters, and n>2. An adder is arranged to add outputs from the n processing paths such that the addition eliminates ghosts of the blocks of data.

Abstract: An adaptive equalizer comprises a decision device; a decision feedback equalizer coupled to the decision device; an FIR filter coupled to the decision device; and a trellis decoder coupled to the decision device, adapted to provide a reliability output and a decoded output. An error signal is generated by subtracting an output of the decision feedback equalizer from an output of the decision device, the error signal being used to update coefficients of the taps of the FIR filter and the decision feedback equalizer. A magnitude of the change to the coefficients is selected based at least in part the reliability output of the trellis decoder.

Abstract: An equalizer that processes blocks of data includes a first finite filter which applies first finite filter coefficients to the blocks of data and a first post-processor which applies first post-processor coefficients to an output of the first finite filter. Ghosts of the blocks of data are not eliminated as a result of the application of the first finite filter coefficients and the first post-processor coefficients. The equalizer also includes a second finite filter which applies second finite filter coefficients to the blocks of data, and a second post-processor which applies second post-processor coefficients to an output of the second finite filter. Ghosts of the blocks of data are not eliminated as a result of the application of the second finite filter coefficients and the second post-processor coefficients. However, an adder adds outputs from the first and second post-processors so that ghosts of the blocks of data are eliminated from an output of the adder.

Abstract: An adaptive equalizer comprises a decision device; a decision feedback equalizer coupled to the decision device; an FIR filter coupled to the decision device; and a trellis decoder coupled to the decision device, adapted to provide a reliability output and a decoded output. An error signal is generated by subtracting an output of the decision feedback equalizer from an output of the decision device, the error signal being used to update coefficients of the taps of the FIR filter and the decision feedback equalizer. A magnitude of the change to the coefficients is selected based at least in part the reliability output of the trellis decoder.

Abstract: An equalizer applies a window function to input blocks of data. A first finite filter multiplies each of the windowed input blocks of data with a first set of finite filter coefficients to provide respective first adjusted output blocks of data. This multiplication does not result in a full solution to ghosts. A second finite filter multiplies each of the windowed input blocks of data with a second set of finite filter coefficients to provide respective second adjusted output blocks of data. This multiplication also does not result in a full solution to ghosts. An adder performs an addition based upon corresponding ones of the first and second adjusted output blocks of data. A controller controls the window function and the first and second sets of equalizer coefficients so that, as a result of the addition, a substantially full solution to ghosts is obtained.

Abstract: An equalizer substantially eliminates a ghost of a received main signal by (i) applying coefficients b (where b may be equal to one) to the received main signal and the ghost in order to modulate the received main signal and the ghost so that the received main signal and the ghost are unequal, (ii) applying coefficients a to the modulated received main signal and ghost in order to substantially eliminate the ghost, and (iii) applying coefficients c as a window function to the substantially ghost-free received main signal in order to remove the modulation imposed on the received main signal by the coefficients b.

Abstract: An equalizer substantially eliminates a ghost of a received main signal by (i) applying coefficients b (where b may be equal to one) to the received main signal and the ghost in order to modulate the received main signal and the ghost so that the received main signal and the ghost are unequal, (ii) applying coefficients a to the modulated received main signal and ghost in order to substantially eliminate the ghost, and (iii) applying coefficients c as a window function to the substantially ghost-free received main signal in order to remove the modulation imposed on the received main signal by the coefficients b.

Abstract: A system and method for symbol clock recovery independent of segment location recovery uses the frequency and phase information in the upper and lower band edges of a signal to generate a signal for correcting the symbol clock. A particular combination of raised-root cosine filters, low-pass filters, multipliers, and adders effectively uses the tails of a received signal in the frequency domain to correct phase errors.

Abstract: A data-directed frequency-acquisition loop capable of generating a frequency error having a magnitude and direction from a double sideband suppressed signal comprises a first multiplier that multiplies the signal by the output of a VCO. The output of the first multiplier is convolved by a second multiplier. The I output of the second multiplier passes through a first low-pass filter. The filtered I output and the Q output are then multiplied by a third multiplier. The output of the third multiplier is filtered through a second low-pass filter, amplified, and return to the VCO to complete the feedback loop.