Abstract: A partial fractionally spaced equalizer for a digital television includes, a feedforward filter unit for receiving an input signal sampled at a predetermined frequency, which is divided a first region having a symbol spaced tap and a second region having fractional spaced taps narrower than the symbol spaced tap, a feedback filter unit having symbol spaced taps, a equalizer signal generator for processing feedforward tap signals outputted from the feedforward filter unit and the feedback tap signals outputted from the feedback filter unit and generating equalizer signals, a slicer for slicing the equalizer signals to generate a decision data and outputting the decision data to the feedback filter unit, and an error generator for generating a compensating error signal by subtracting the equalizer signal from the decision data. When a sampled input signal (Si) of 21.

Abstract: Device and method for correcting a color distortion on a TV receiver, is disclosed, the method including a multi-path channel estimation step wherein a transmission channel existing between a transmitted side in a broadcasting station and a color demodulating circuit in a TV receiver is estimated for obtaining an impulse response using a reference signal transmitted from the broadcasting station for equalizing a multi-path channel, a color subcarrier phase error calculation step wherein a phase error of a color subcarrier between the transmitter side of the broadcasting station and the TV receiver is calculated using the estimated impulse response, and a phase correction of a reproduced color subcarrier step wherein a phase error on the TV receiver in reproduction of a color is corrected as much as the phase error obtained in the color subcarrier phase error calculation step.

Abstract: A digital/analog TV common-use receiver having a single ghost canceler, and a ghost cancellation method are provided. The single ghost canceler includes a first filter coefficient generator for generating first filter coefficients using a first reference signal included in the analog TV signal, a second filter coefficient generator for generating second filter coefficients using a second reference signal included in the digital TV signal, and a digital filter for filtering the analog TV signal using the first filter coefficients if the analog TV signal is received, and the digital TV signal using the second filter coefficients if the digital TV signal is received. Since an equalizer used when receiving a terrestrial digital TV broadcast is also used upon receiving a terrestrial analog TV broadcast, the single equalizer can correspond to both digital and analog TV signals.

Abstract: A linear filter for use in 8 MHZ television broadcast systems is provided having a frequency response which includes a notch corresponding to a television picture carrier fpix, a notch corresponding to approximately a television color subcarrier fcs, and a notch corresponding to approximately a television sound carrier fs. Accordingly, the linear filter substantially reduces co-channel interference in a digital signal received by a digital television.

Abstract: An apparatus and method for determining co-channel interference in a DTV system is disclosed including a first comb filter filtering the received digital data including a data field signal; a pattern generating unit generating a reference sync signal from the data field signal; a second comb filter filtering the reference sync signal; a selection unit receiving either the digital data that passed or have not passed the first comb filter to output one of the data in response to a selection signal; a determination unit determining the presence of a co-channel interference; a first counting unit counting up/down a counted value in response to an output signal of the determination unit; and a second counting unit counting the reliability of the counted value output from the first counting unit, and providing the selection signal to the selection unit.

Abstract: A receiver including an NTSC rejection filter for eliminating interference signals from a high definition signal. The ratio of the energy of an expected high definition signal to the energy of an NTSC signal is determined. An NTSC signal sequence is generated according to the determined ratio. The number of filter taps is determined, and an autocorrelation matrix of the NTSC signal is calculated using the generated NTSC signal sequence. The power of all interference noise in the output of the NTSC rejection filter is used as a cost function, with respect to the input NTSC interference signal, the additive Gaussian noise and the VSB signal. A filter coefficient equation, for minimizing the cost function, is obtained by differentiation, and then the autocorrelation matrix is substituted for the equation, to calculate coefficients of the NTSC rejection filter.

Abstract: An adaptive channel equalizer for a digital television receiver includes memory for storing channel characterization information for each received channel, from each time the channel is tuned to until the next time the same channel is tuned to. The stored information is retained even if operating power to the receiver is interrupted. Whenever operating power is restored to the receiver after interruption and whenever a channel is tuned to again after having tuned to another channel, the previously stored channel characterization for the currently tuned channel is retrieved from memory. The retrieved channel characterization is used to calculate initial filter coefficients for the adaptive channel equalizer.

Abstract: The data field synchronization segment as symbol coded for VSB transmission comprises pseudo-random noise (PN) sequence information that can be detected using a match filter in a QAM/VSB DTV signal receiver. The data field synchronization segment as symbol coded for QAM transmission does not contain the PN sequence information that can be detected using the same match filter used for detecting the PN sequence information in the VSB transmission. A threshold detector is used for determining whether the match filter response is of sufficient energy to indicate occurrence in a received DTV signal of the PN sequence information in the data field synchronization segment of a VSB DTV transmission. Timed latch circuitry is used for latching the indication for a period of time longer than at least one DTV data field. The QAM/VSB DTV signal receiver is operated either in a QAM reception mode or in a VSB reception mode, depending on the output signal of the timed latch circuitry.

Abstract: Composite ghost cancellation reference (GCR) signals that make available both a chirp and a PN sequence during the same vertical-blanking-interval (VBI) scan line in each successive field facilitate more rapid and efficient calculations of ghost cancellation and of equalization, on a continuing basis. A television receiver for use with such composite GCR signals includes circuitry for separating the chirp and PN sequence portions of the GCR signals from the remainder of the composite video signal, a ghost cancellation filter and an equalization filter connected in cascade to respond to the composite video signal and provided each with adjustable filtering weights, and a computer. Random-access memory addressed during writing snatches the vertical-blanking-interval scan lines selected to include GCR signals. Sets of four successive ones of the selected scan lines are then additively and subtractively combined to separate the chirp portions of the GCR signals from a remainder of the composite video signal.

Abstract: An apparatus for receiving a television signal containing a ghost cancellation reference signal, and for using the reference signal to process the television signal so as to substantially eliminate path induced distortion.

Abstract: A digital television signal receiver in a television set or in a digital video recorder digitizes received digital television signal as converted in frequency to a final intermediate-frequency band close to baseband, then performs equalization filtering on the digitized signal before demodulating it in the digital regime to regenerate baseband symbol coding. The equalization filtering is adaptive, and weighting coefficients for this filtering are adjusted in response to portions of the regenerated baseband symbol coding. Initial adjustment of the weighting coefficients is preferably done using selected portions of the data field synchronizing signal as a ghost cancellation reference signal, in order that convergence of the weighting coefficients to desired values proceeds more rapidly.

Abstract: A system for filtering digital television signals is provided. The system comprises a generator for providing a first data sequence to a private data packetizer, and a transmitter for transmitting the packetized first data sequence in a data channel of a digital television signal. The system further includes a receiver for receiving the digital television signal and recovering the first data sequence. The receiver includes a channel estimator for providing an estimate of channel characteristics, such as estimated channel impulse estimate and estimated noise variance. The receiver further includes an adaptive equalizer filter having an input for receiving the digital television signal and an input for receiving adaptive filter coefficients. The receiver further includes a coefficient processor for calculating adaptive filter coefficients based on the channel estimate, and providing the adaptive filter coefficients to the adaptive equalizer filter.

Abstract: Training signal for channel equalization is located in the initial data segment of each DTV data field and in the nineteenth scan line of each NTSC field. Arranging for training signal separated from plural PN sequences near the beginnings of the initial data segments of DTV data fields improves post-ghost detection capability in the DTV system. In receivers for receiving NTSC signals and DTV signals, arranging for training signal to be separated from plural PN sequences near the beginnings of the nineteenth scan line of each NTSC field facilitates the same ghost-cancellation and channel-equalization filtering being used both during the reception of NTSC signals and during the reception of DTV signals.

Abstract: This invention permits the upstream transmission of short packets of information in a cable TV system, and blocking upstream noise at all other times, and does so without interfering with image quality of normal TV viewing. A remotely operable ingress noise blocking filter is placed at the terminating junction between a subscriber's coaxial drop cable and a corresponding feeder tap in a cable TV system. The ingress noise blocking filter contains a high pass filter to pass the normal TV band. This high pass filter is bypassed by a section containing low pass filters and a switch operated when receiving a control signal from a cable modem during those short durations the cable modem is authorized to transmit an upstream signal. Low pass filters isolate the switching elements so that switching transients cannot occur in the downstream TV band. The level of the amplitude of the downstream signal is unaffected whether the switching elements are open or closed.

Abstract: Baseband DTV signals are supplied to a cascade filter connection of a transversal filter operative over many data segments and a match filter for data segment synchronizing (DSS) signals. The accumulated random data in the cascade filter response is suppressed by coring, to generate a signal ensemble descriptive of ghosted DSS signal. The transmission channel is characterized based on this ensemble, and the coefficients of a complementary channel-equalization and ghost cancellation filter are calculated based on this characterization.

Abstract: A method and apparatus are provided for performing host-based anti-ghosting of teletext data in a television signal using non-oversampled data. Teletext data is first encoded within a television signal using multi-level error correction encoding, including the use of an inner correction code and an outer correction code. The television signal is then transmitted using multiple signal level modulation encoding, while adhering to the standard teletext timing. A remote computer system receives the television signal containing the encoded teletext data. A tuner/capture subsystem of the computer system oversamples the teletext data and uses the oversampled data to reconstruct the bit peaks of the teletext data. The teletext data are then provided to a main memory of the computer system via a host interface as non-oversampled data. The host processor performs anti-ghosting, data slicing, and multi-level decoding of the teletext data based on the non-oversampled data.

Abstract: A television receiver for processing both analog television signals and digital television signals. Specifically, the television receiver contains a RF/IF front end, an analog-to-digital converter that samples a near baseband signal using a "free running" sample rate, and a combined demodulator that demodulates the digitized analog television signals or the sampled digital television signals. The combined demodulator recovers both pilot and pix carriers as well as provide a passband adaptive equalizer that removes ghosts from analog television signals and intersymbol interference from digital television signals.

Abstract: A noise suppressor has signal detecting device 1 for detecting signals A and B on signal lines, sum signal generating device 21 for summing the detected signals, difference signal generating device 22 for differencing the detected signals, noise canceling device 3 for suppressing or removing noise components in a difference signal generated by the difference signal generating device and signal separating device 4 for separating the signal to those corresponding to the signal lines, according to the difference signal with the noise components suppressed or removed and the sum signals.

Abstract: A method for cancelling ghost effects in an image signal processor which is capable of enhancing a convergence rate of a coefficient of a filter and a performance of cancelling ghost effects in a system, by alternately performing the updatings of the coefficients of an FIR filter and an IIR filter in a system using both the FIR filter and the IIR filter, includes initializing an FIR filter bank and an IIR filter bank, updating the FIR filter bank by performing an algorithm for updating a coefficient of a filter with a data having a ghost effect and a data in which a reference GCR data is filtered by the IIR filter, updating the IIR filter bank by performing the algorithm for updating a coefficient of a filther with the reference GCR data and a data in which an X(z) is filtered by the FIR filter bank, and obtaining an FIR filter bank and an IIR filter bank in each of which an error is minimized.

Abstract: A co-channel interference canceler and a method therefor. The co-channel interference canceler includes: a co-channel interference rejection filter for outputting a second input signal by removing co-channel interference from a first input signal; a first post processor for removing interference other than co-channel interference from the second input signal; a second post processor for removing interference other than co-channel interference from the first input signal; and a selection controller for selecting the output of the post processor which has less error by comparing the output of the first post processor with the output of the second post processor. Therefore, other interference such as ghost and phase noise included in an input signal are removed or reduced via the extra second post processor which is different from the first post processor of the signal path.

Abstract: A ghost removal apparatus to prevent visual emphasis of image noises when removing ghosts. A transparent characteristic of an image signal is changed with respect to frequency characteristics of ghost removing filters at a frequency of at least 4.2 MHz depending on amounts of noises included in the image signal, and an equalizing characteristic of the image signal is changed with respect to the frequency characteristics of the ghost removing filters at a frequency of at most 4.2 MHz depending on the amounts of the noises.

Abstract: A co-channel interference canceler and a method therefor. The co-channel interference canceler includes: an NTSC interference rejection filter (NRF) for removing co-channel interference from an input signal; a noise reducer for reducing noise by removing interference other than co-channel interference from the input signal; and a selection controller for determining whether or not co-channel interference exists in the signal output from the noise-reducer and selecting the NRF when such co-channel interference exists in the noise reduced signal. Therefore, the effect from interference other than the co-channel interference is minimized, so that the co-channel interference controller is reliably controlled.

Abstract: A digital filter processing device receives image data of a frame in the order of time series in scanning the frame for carrying out a filter process for every group of image data corresponding to each of a plurality of regions of a predetermined size in the frame. The device receives image data in the order of time series of the scanning operation of a frame to multiply the input image data by a corresponding filter coefficient. This multiplied result is accumulated for every group to be output as an accumulation result. As a result, a region for storing a multiplied result which is an intermediate result of the filter process and an operation for reading out the multiplied result from the storage region for accumulation can be eliminated. Therefore, a filtering process of a frame can be carried out at high speed and in real-time.

Abstract: Connector switch apparatus which can provide either a cable or satellite television signal or a ghost-free off-air television signal. The apparatus obtains the cable or satellite television signal from a cable or satellite tuner, which can be included in the apparatus; and includes a television tuning device for producing a ghost-free off-air television signal, and a switch which provides either of those signals. The television tuning device employs use of antenna directionality control and ghost cancellation to produce a ghost-free off-air television signal. In particular, the television tuning device obtains an off-air television signal from a antenna, which may or may not be included therein, whose directionality can be changed to change reception quality of a received off-air television signal; and includes a baseband ghost cancellation unit which can perform baseband ghost cancellation.

Abstract: A system and method for demodulation of an RF signal on a transmission channel is provided. The RF signal is demodulated to baseband as an in-phase (I) data signal and a quadrature (Q) data signal. A first block of I data is captured and a first block of Q data is captured. A time domain guard interval is provided in the captured first blocks of I and Q data. A complex discrete Fourier transform is performed on the captured first I and Q data blocks. An inverse frequency response for the transmission channel is determined. The inverse frequency response is multiplied by the complex discrete Fourier transform of the guard-interval protected first I and Q data blocks to generate a frequency domain product signal. An inverse Fourier transform on the product of the multiplying step is performed to generate a first equalized time domain signal. In a preferred embodiment, the method also includes using an overlapped Fourier transform and discarding a first portion of each equalized time domain signal.

Abstract: An equalizing method and device for equalizing a received signal by renewing a filtering coefficient of a filter in an off-line system using a pre-stored reference signal. It is first determined whether or not a signal input to a high definition TV (HDTV) includes a field sync or not. If so, the detected field sync is stored in a memory as a training sequence. A filtering coefficient is calculated according to a predetermined algorithm, and a symbol error rate (SER) is calculated using the pre-stored reference signal. The filtering coefficient is transmitted to the filter when the calculated SER is lower than a predetermined value.

Abstract: An electronic imaging apparatus includes an optical system and a digital filter for providing focus values for focusing the optical system upon a color image sensor. The color image sensor, which operates at a pixel clock frequency to provide image data, has a repeatable color pattern including a luminance color which recurs at a predetermined repetition rate that is a submultiple of the pixel clock frequency. The digital filter includes a plurality of filter coefficients that are applied to the image data in groups of coefficients to implement a digital bandpass filter function. In particular, an arrangement of processing elements performs a sequence of multiplications upon the input data, each multiplication generating an output value dependent upon the value of a coefficient applied to a corresponding processing element. An arrangement of multiplexers sequentially apply the groups of coefficients to the arrangement of processing elements in synchronism with a submultiple of the pixel clock frequency, e.g.

Abstract: A method for processing a signal in a CSD filter includes the steps of obtaining real coefficients optimized to desired filter characteristics, calculating scaling factors for each real coefficient which minimizes errors between the real coefficients and converted CSD codes, producing optimum CSD coefficients by using the calculated scaling factors, and filtering input data by using the optimum CSD coefficients. In the method of the present invention, conversion of the real coefficients into the CSD coefficients is performed in the time domain, thereby improving operating speed and increasing bit resolution with the number of non-zero digits fixed, as compared to conversion in the frequency domain. As a result, the present invention can be applied to an adaptive filter and a polyphase filter.

Abstract: Embodiments of methods and apparatuses for removing ghosts from a signal such as a communications signal received over a channel where the output symbol pattern is used for selecting correction factors for correcting the received symbols. The correction factor is added to the sampled symbols and the sampled symbol is compared with a selected one of a plurality of thresholds based upon the closeness of the various thresholds to a sequence of the corrected symbol values. That comparison forms the basis for the next output symbol in the output sequence. Further, the selected correction factor is updated by taking the difference between the selected correction factor and an error measurement between the corrected sample value and the nominal value of the symbol times a damping factor. At various points in the sequence, the output is forced to an expected symbol sequence such as a clocking sequence used for clock recovery.

Abstract: A method and apparatus of reducing interference in a broadband radio frequency link is disclosed. Different signals are received by two antenna elements, in a first case the signals comprise differently polarized signals at the same or an offset frequency; in a second case the signals comprise a wanted signal and an interference signal, wherein the interfering signal is treated as an independent channel. The method comprises the steps of receiving radio frequency signals on two independent paths, selecting a portion of the radio frequency signal in each receive path or the desired signal path after demodulation where a predetermined frequency or band of frequencies is known to be absent; measuring the signal power; determining weights in a feedback path; and applying the feedback control signals to an algorithm which determines the weight(s) applied to the wanted signal such that the signal power in the summed signal(s) due to the interfering signal is reduced or cancelled.

Abstract: A method and apparatus for the self-correcting of anti-ghosting filter coefficients is provided. A plurality of coefficients associated with an anti-ghosting filter are monitored as data is received by the filter. The plurality of coefficients are adjusted if one or more of the plurality of coefficients exceed a first value. In one embodiment, the filter is an adaptive baseband equalization filter. If the magnitude of one or more secondary coefficients of the adaptive baseband equalization filter exceed a predetermined factor of the primary coefficient, then the plurality of coefficients are adjusted. In another embodiment, the filter is a lookup table filter. If the magnitude of a coefficient in the lookup table is greater than a predetermined value, the plurality of coefficients are adjusted.

Abstract: A video surveillance system includes a remotely controllable video camera which generates a video signal, a video switch, a cable for transmitting the video signal from the video camera to the video switch, a control circuit connected to the cable for generating control signals to be transmitted to the video camera via the cable, and a control signal receiver associated with the camera and connected to the cable for receiving the control signals transmitted via the cable. The control signal receiver includes a detection circuit for automatically detecting the length of the cable and generating an adjustment signal indicative of the detected length of the cable. The control signal receiver also includes an adjustable circuit element which is adjusted on the basis of the adjustment signal so as to compensate for the detected length of the cable. The automatic cable compensation in the control signal receiver provides reliable detection of the camera control signals.

Abstract: A color separation prism in which are arranged, in the order according to the direction in which the light from the objective travels: a first prism which extracts a predetermined wavelength component; a first air gap; a second prism which extracts a predetermined wavelength component; a second air gap; and third and fourth prisms that are joined to each other, wherein, in particular, a light reflected by the joint plane is totally reflected by a surface adjacent the second air gap and guided to an image pickup device.

Abstract: A method for filtering a time signal (e(t)) sampled in blocks of N samples (e(n),e(k)) uses a transfer function defined in the frequency domain by LN samples (H(K)). The transfer function is filtered by a time window (g1) of width N, and a frequency subsampling of ratio N is performed to give a partial transfer function defined over N samples (H1(k)). The method enables the complexity of circuits operating in real time to be optimized. The technique is particularly suitable for correcting long echoes in television picture receivers.

Abstract: A method and apparatus for channel identification utilizing two Least-Squares (LS) estimators. Each LS estimator is used for calculating a sequence of channel values, further for determining an estimated channel impulse response, over an entire frequency band thereof in light of the fact that information is incomplete or unreliable over part of the frequency band. Each LS estimator operates for the case when the estimated channel impulse response span is less than the span of a known test signal, the test signal having been transmitted over the channel for use in identifying the channel. In a TV ghost-cancellation system for removal of channel induced distortion from received signals, each LS estimator is used to compute channel impulse response coefficients, wherein the system includes ghost-cancellation filters responsive to the channel impulse response for removing the effects of the channel from the signals.

Abstract: An antenna and a tuner are used for receiving TV signals that carry static images at 30 frames per second. Fifteen frame memories are provided in a image memory unit and a microprocessor sequentially stores the received images in each of the frame memories and evaluates the quality of each of the stored images. Furthermore, display patterns are obtained by varying frame speeds and phases with the image quality for each display pattern being evaluated thereafter. The pattern having the highest score is selected and the oldest image among the images stored corresponding to the selected pattern is displayed on the display in accordance with a predetermined condition.

Abstract: In a radio receiver for receiving vestigial sideband (VSB) signals including symbol codes descriptive of digital signals, HDTV signals being exemplary of such VSB signals, a tuner provides for selecting one of channels at different locations in a frequency band used for transmitting such VSB signals. The tuner also includes mixers for performing plural conversion of the selected channel to a final intermediate-frequency signal, which is digitized by an analog-to-digital converter. A phase tracker, operative on narrow-bandpass filtered portions of the digitized final intermediate-frequency signal centering on its carrier frequency, suppresses an imaginary portion of the final intermediate-frequency signal, arising from multipath distortion or from phase incoherency in local oscillations used during frequency conversion.

Abstract: An equalization apparatus for use in a television system includes a equalizer filter having a plurality of equalizer coefficients and an updating circuit. In the updating circuit, the equalizer coefficients are adjusted by using two computational terms: a CMA term; and a Cauchy term in order to effectively make the equalizer to converge to the global minimum of the coarse MSE function all the time. Both terms decrease to zero as the equalizer coefficients approach to a minimum, but in different ways: the first CMA term decreases to zero monotonously; and the value of the second Cauchy term fluctuates up and down, depending on the selected value for the Cauchy distribution function and thus temporary increases, although contained, are allowed during the process. A combination of the two terms with a proper choice for the weight factors prevents the equalizer coefficients from converging to a local minimum of the coarse MSE function and makes them converge to the global minimum thereof all the time.

Abstract: Within a desired service area, multiple transmitters at separately located sites simultaneously broadcast the same multi-channel, multi-program signal. Broadcast waves from the transmitters propagate throughout substantially overlapping portions of the service area. Each broadcast channel carries a multiplexed digital data stream containing packets of information for a plurality of programs, e.g. television programs. A shared antenna system, typically including multiple receiving antennae aimed at a plurality of the transmitters, supplies received signals to terminals in a plurality of living units. The shared system includes delayed signal processing circuitry to supply an optimal signal from the receiving antennae to the terminals.

Abstract: A channel equalizer for a digital television receiver which filters an input signal to remove a noise component mixed therewith during transmission. The channel equalizer comprises an initial coefficient storage unit for outputting a predetermined coefficient to channel equalizer circuit when a certain channel is firstly selected. The predetermined coefficient is used as an initial filtering value for allowing the channel equalizer circuit to update a filtering coefficient so that it can converge on an optimum value. The stored filtering coefficient is output to the channel equalizer circuit when the firstly selected channel is again selected, so that it can be used as the initial filtering value.

Abstract: Television tuning systems and methods employing use of ghost cancellation and antenna directionality control to produce a ghost-free television signal. The invention employs use of a antenna whose directionality can be changed to change reception quality of a received television signal, and a baseband ghost cancellation unit which can perform baseband ghost cancellation. In a first embodiment of the invention, the directionality of the antenna is changed so that a television signal of sufficient reception quality is received from which a ghost-free television signal can be produced therefrom by the baseband ghost cancellation unit. A second embodiment of the invention further employs use of a tuner, and involves controlling the directionality of the antenna and the tuning frequency of the tuner so that a tuned television signal is produced which is properly tuned and of sufficient quality that a properly tuned ghost-free television signal can be produced therefrom by the baseband ghost cancellation unit.

Abstract: Within a desired service area, multiple transmitters at separately located sites simultaneously broadcast the same multi-channel, multi-program signal. Broadcast waves from the transmitters propagate throughout substantially overlapping portions of the service area. Obstructions in the service area, e.g. mountains, buildings, trees, etc., may block reception from one or more of the transmitters at certain sites. However, at most receiving sites, the receiving antenna can receive a clear line-of-sight transmission from at least one of the transmitters. In the preferred implementation, the channels are 6 MHz wide channels broadcast in the super high frequency microwave portion of the spectrum. Each such channel carries a multiplexed digital data stream containing packets of information for a plurality of programs, e.g. television programs.

Abstract: An improved ghost prevention apparatus for a television capable of preventing ghost of a picture of a television, which occurs due to a detection wave distortion, by generating a key pulse within a part of a horizontal synchronous section of a timing signal generator, by turning on an automatic phase controller for the key pulse generation section and turning off the same for the remaining horizontal synchronous, which includes a synchronous separator for separating horizontal and vertical synchronous signals, respectively, from a combined picture signal detected by a picture wave detector; a timing signal generator for generating a key pulse in a horizontal synchronous range in accordance with a horizontal synchronous signal outputted from the synchronous separator and for generating a vertical blanking signal in a vertical synchronous range in accordance with a vertical synchronous signal; a first sampling holder for sample-holding a phase control signal outputted from the picture wave detector, outputting

Abstract: A circuit for detecting and synchronizing a ghost cancellation reference (GCR) signal in a television video signal, includes a circuit for receiving at least one field of an input video signal, a circuit for finding a maximum correlation peak value in a field of said input video signal, a circuit for scaling the maximum correlation peak value to a lower predetermined value for detection for forming a scaled peak value, a circuit for synchronizing a next field of the video signal using the scaled peak value, and a circuit for predicting a future position of the GCR signal.

Abstract: A ghost canceler uses a filter coefficient represented in canonical signed digit code to cancel a ghost of a video signal. The ghost cancelling apparatus includes an input end for receiving a ghost-containing video signal, a separation and storage portion for separating a transmitted ghost cancelling reference (GCR) signal from the video signal received via the input end, and storing the separated GCR signal therein, a controller for receiving the GCR signal stored in the separation and storage portion to detect a characteristic of a channel through which the video signal is transmitted, and generating canonical signed digit (CSD) filter coefficient values represented in the form of CSD codes on the basis of the detected channel characteristic, and a filter for cancelling a ghost component contained in the video signal received via the input end on the basis of the CSD filter coefficient values generated by the controller, and outputting the ghost-cancelled video signal.

Abstract: In a ghost cancellation system, it is necessary to synchronize the system to the ghost cancellation reference (GCR) signal contained in the video signal. A free-running oscillation, having a frequency which is the same as that used in generating a reference GCR signal, is used to clock the sampling of the video signal. This assures frequency coherence between the input GCR signal and the stored reference GCR signal. By using cross-correlation, the phase error between the sampled input GCR signal and the stored GCR signal is determined. Based on this phase error, a phase-corrected reference GCR signal is generated and stored. This phase-corrected reference GCR signal is then used in the generation of an error function involving the sampled input GCR signal, the error function being used for eliminating ghosts in the input video signal.

Abstract: A first composite video signal may include attendant ghosts and sometimes includes in a prescribed L.sup.th line of each field during the vertical blanking interval one of a cycle of M ghost-canceling reference (GCR) signals of prescribed magnitude and respective phasing. Filter circuitry generates a second composite video signal in response to the first composite video signal, which is adjusted in response to filter programming signals generated by a computer storing a ghost-free GCR signal. The computer receives a GCR signal with attendant ghosts and compares it to the stored ghost-free GCR signal, thereby carrying out correlation procedures for calculating the filter programming signals. The second composite video signal is a response to the first composite video signal in which the attendant ghosts are lessened.

Abstract: A system for improved echo cancellation for use in particular in television receivers. The system features a superior ghost cancellation reference signal which exhibits improved performance in noisy environments and which exhibits the flat and wide bandwidth necessary for effective channel characterization while exhibiting a higher and more evenly distributed amplitude versus time characteristic than that provided by known, non-cyclic ghost cancellation signals.

Abstract: A method and apparatus for shaping the impulse response of a non-minimum phase communications channel, by reversing the CIR without enhancing the noise level using non-causal allpass filters is disclosed. Unstable allpass filters are implemented as stable non-causal filters operating in reversed time to obtain a minimum phase response from a non-minimum phase CIR. The original CIR is estimated using adaptive algorithms, and the coefficients of the allpass filters are taken directly from the estimated CIR. The cascade of the channel and allpass filter has an impulse response that is the approximate time reversed version of the original CIR. A "block" allpass equalizer and an "optimal" allpass equalizer are used in a two-stage filter to increase system performance. Other multiple stage filter configurations are disclosed, which can include use of decision feedback equalizer (DFE) decoders as well as Viterbi decoders.

Abstract: A partial response Trellis decoder that performs Trellis coded modulation in a high definition television (HDTV) having a specific and detailed configuration and includes a distance mapper for calculating first, second, third and fourth Euclidean distances between the input signal and a reference value; a Viterbi decoder for Viterbi decoding the first, second, third and fourth Euclidean distances calculated by the distance mapper; a first delay for delaying and outputting the Yiterbi decoded data for each Euclidean distance; a ruler selector for selecting a ruler type signal based on the signals output by the first delay; and a slicer for slicing the selected ruler type signal and the input signal.