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 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: During a period of transition from broadcasting analog TV signals to broadcasting digital TV signals, digital TV reception is susceptible to disruption owing to co-channel interference by analog TV signals. During this same transition period usually a digital TV receiver will incorporate an auxiliary analog TV receiver. This auxiliary analog TV receiver is advantageously used during digital TV signal reception for determining the amount of co-channel interference by analog TV signals, so that comb filtering can be selectively applied to symbol coding recovered from the digital TV signal, for suppressing artifacts of co-channel interfering analog TV signal when they are large enough to have substantial adverse on symbol decoding. The amount of NTSC co-channel interference is estimated by detecting the level of intercarrier generated by mixing the audio and video signals of the analog TV 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: A method and apparatus for improved interference rejection, where the rejection is being accomplished by an IIR filter at the transmitter with complementary characteristics to an FIR filter of the receiver, such as a Tomlinson-Harashima transmit-precoder. The improvement is accomplished by providing the ability to preset the transmit and receive filters to the same state, thereby allowing for subsequent receptions to be deterministic. This method and apparatus is particularly useful for correcting for time-varying interference through the use of repeatable, deterministic, training sequences.

Abstract: A method and apparatus for transmitting and receiving frequency hopped video signals is disclosed. A composite video signal is processed at a transmission end to remove line and frame synchronization codes and replace them with a frequency hopping synchronization code. The signal is then modulated with a frequency hopped carrier signal and transmitted to a receiver. The receiver detects the frequency hopping synchronization code to enable tuning of the receiver to the video signal. The detected frequency hopping synchronization codes are removed and replaced with the original line and frame synchronization code. The recreated video signal may be digitized and processed to detect and correct errors within the video signal by replacing lines or frames of the video signal with closely related lines or frames from another portion of the video signal.

Abstract: An arrangement (apparatus and method) for obtaining a single copy of a received signal from a simulcast broadcast area. 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 such channel carries a multiplexed digital data stream containing packets of information for a plurality of programs, e.g. television programs. A receiver system comprises an antenna adapted to receive direct transmissions from two or more of the transmitters as well as multipath signals from two or more of the transmitters. To compensate for the potentially interfering signal receptions, the terminal device includes a delay processor, such as an adaptive delay equalizer or a rake receiver.

Abstract: A digital television signal receiver includes, instead of a single flash converter as in the prior art, MN analog-to-digital converters of successive binary approximation type sampling baseband symbol coded signal on an MN-phase basis to provide a respective digital output signal, each of which sampling phases is of one-M.sup.th symbol time duration, M being a positive integer at least one and N being a positive integer more than one. In a digital television signal receiver for ATSC standard signals, N is twelve. Equalization filtering is carried forward on an MN-phase basis, with output signals from N of the phases being supplied to N trellis decoders as their respective input signals. Selecting M to be two facilitates symbol synchronization using first and second N-phase match filters for a prescribed pseudo-noise sequence in the data field synchronization codes.

Abstract: A method for detecting when a digital television signal is accompanied by co-channel interfering NTSC signal of substantial amplitude is described for use in a digital television receiver. The video portion of any co-channel interfering NTSC signal is synchrodyned to baseband, for generating an in-phase demodulation result including first artifacts of the digital television signal, and for generating a quadrature-phase demodulation result including second artifacts of the digital television signal. The quadrature-phase demodulation results are phase shifted by 90.degree. at frequencies in a prescribed frequency range before being linearly combined with the in-phase quadrature-phase demodulation results, to generate a linear combining result substantially free of the first and second artifacts of the digital television signal in the prescribed frequency range.

Abstract: Co-channel interference accompanying multiple-level symbols in a digital receiver, such as a digital television receiver, is suppressed by using a first comb filter to reduce the energy of the co-channel interference before data slicing. The first comb filter incidentally precodes the symbol decoding results generated by the data slicing. A second comb filter postcodes the precoded symbol decoding results from the data slicing to generate corrected symbol decoding results. The symbol precoding of the input symbol stream results from differential delay and first linear combination of the differentially delayed terms. The postcoding of the symbol stream recovered by data slicing results from second linear combination of the symbol stream with delayed result of the second linear combination, and is performed in accordance with a modular arithmetic. One of the first and second linear combinations is subtractive, and the other is additive.

Abstract: A VSB mode detection circuit with a comb filter solves the potential problem of lockout in a situation where an 8 VSB mode signal is being received, with the comb filter being effective, and a change in signal mode suddenly occurs. The arrangement inhibits the first two bytes of the three byte mode information, which two bytes are unspecified for all except the 8 VSB terrestrial mode, and replaces them with zero data. In another embodiment, the 12 symbol delay in the comb filter is bypassed with the complement of the input data for the third byte. When the 8 VSB terrestrial mode has been confidently determined to exist, the inhibition of the first and second bytes (and the inversion of the bypassed third byte) is removed in alternate fields to permit normal comb filter operation.

Abstract: A digital television receiver operating in the presence of an NTSC co-channel signal includes an NTSC rejection filter that is selectively inserted in the digital television signal path to minimize interference from the NTSC co-channel signal. The energy around the NTSC picture carrier is sampled. This is compared with sampled white noise energy between the NTSC picture and color carriers, after field combing the digital television signal to eliminate the effects of static signals. The comparison is used to determine whether or not the NTSC rejection filter is inserted in the digital television signal path.

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: Symbol decoding results obtained using comb filtering to suppress artifacts of NTSC co-channel interference before symbol decoding and symbol decoding results obtained without using such comb filtering before symbol decoding are compared for determining which symbol decoding results are to be selected as final symbol decoding results. Symbol decoding results obtained using comb filtering to suppress artifacts of NTSC co-channel interference are selected as final symbol decoding results when NTSC co-channel interference occurs. The digital television signals are detected to determine whether 4.5 MHz NTSC intercarrier obtains, in order to confirm the occurrence of substantial NTSC co-channel interference.

Abstract: During a period of transition from broadcasting analog TV signals to broadcasting digital TV signals, digital TV reception is susceptible to disruption owing to co-channel interference by analog TV signals. During this same transition period usually a digital TV receiver will incorporate an auxiliary analog TV receiver. This auxiliary analog TV receiver is advantageously used during digital TV signal reception for determining the amount of co-channel interference by analog TV signals, so that comb filtering can be selectively applied to symbol coding recovered from the digital TV signal, for suppressing artifacts of co-channel interfering analog TV signal when they are large enough to have substantial adverse on symbol decoding. The amount of co-channel interference is estimated from synchronously detected analog TV signal.

Abstract: Post-coder selection circuitry uses an NTSC interference detector for controlling the selection of whether post-coding is to precede trellis decoding in an HDTV receiver. The NTSC interference detector includes an NTSC extracting filter for supplying an NTSC extracting filter response that separates accompanying co-channel interfering NTSC signal component from the received I-channel baseband signal including its direct bias component. The NTSC interference detector includes a comparing portion for periodically integrating the NTSC extracting filter response and deciding whether the co-channel interfering NTSC signal component from the I-channel baseband signal is above a first reference value or not.

Abstract: When both an NTSC signal and an ATV signal are concurrently broadcast in a co-channel, it is desirable to remove the NTSC signal at the receiver when reproducing the broadcast ATV signal, since the NTSC signal would interfere with the ATV signal. An NTSC rejection filter is used to remove most of the signal power of an NTSC broadcast signal. To more effectively handle multipath interference signals, the present invention adaptively controls the driving selection of an NTSC rejection filter. The mean power levels are calculated for an input signal which has not been NTSC rejection filtered and for a second input signal which has been NTSC rejection filtered. Error differences are then calculated for each of these mean power levels and a driving selection is determined for the NTSC rejection filter based upon the calculated error differences.

Abstract: A device and method for removing co-channel conventional television signal interference from a digital signal by using an-adaptive filter which tunes to the periodic components of the conventional television signal. The output of the adaptive filter is then subtracted from the received signal to produce an error signal. This error signal is then used to recursively update the taps of the adaptive filter. The invention also relates to the use of the adaptive filter in conjunction with a DFE.

Abstract: An arrangement and method for detecting sequential processing effects on devices to be manufactured in a manufacturing process extracts data regarding responses of the devices to a process step in the manufacturing process and data regarding a processing sequence of the devices in that process step. The extracted data is refined before analysis and control chart rules are then applied to the refined data. These control chart rules detect whether there are any unusual processing effects caused by the sequence of processing of the devices in any one of the individual processing steps. Application of control chart rules to the refined data allows an automatic determination of whether there are any rule violations. One or more control charts which have a rule violation are automatically generated when it is determined that there is a rule violation. Process engineers may then use the automatically generated charts to direct their efforts at improving the manufacturing process.

Abstract: Co-channel interference accompanying multiple-level symbols in a digital receiver, such as a digital television receiver, is suppressed by using a first comb filter to reduce the energy of the co-channel interference before data slicing. The first comb filter incidentally carries out a symbol re-coding procedure of first type that introduces error into the symbol decoding results generated by the data slicing. A second comb filter carries out a symbol re-coding procedure of second type after the data slicing to compensate for the symbol re-coding procedure of first type and generate corrected symbol decoding results. The symbol re-coding procedure of first type re-codes an input symbol stream through differential delay and first linear combination of the differentially delayed terms.

Abstract: A television receiver for reducing a co-channel interference in a digital television signal transmitted by a transmitter, wherein the digital television signal includes an encoded digital television signal component, a co-channel interference component, and a noise component, and wherein a precoder, for which precoding is implemented at the television transmitter, encodes the digital television signal. The receiver includes a receiver for receiving the transmitted digital television signal and for providing a received output signal. A filter block is provided for filtering the received output signal to reduce the co-channel interference component thereof. The filter block includes a plurality of rejection filters and a device for enabling a desired one of the plurality of rejection filters in response to a selection control signal, the enabled rejection filter corresponding to an optimal rejection filter for the precoder for which precoding is implemented at the television transmitter.

Abstract: A cellular system for distributing a plurality of television programs in a desired service area. A plurality of groups of spaced transmitting antennas are disposed substantially on the peripheries of adjacent cells disposed in the service area. The antennas are directional and directed to propagate substantially simulcast signals into the cell with which the antenna is associated so that the propagation patterns of the transmitting antennas associated with the cell overlaps over substantially a major portion of the area enclosed within the cell. Antennas disposed substantially on the peripheries of adjacent cells propagate directional signals into each of the adjacent cells. In a broadcast version the frequencies of the signals transmitted by all of the antennas are the same. In a dedicated service version the frequencies of the signals transmitted into adjacent cells are different.

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 substantially throughout the service area and overlap in a substantial portion of the area. The signals are broadcast as spread spectrum signals and the receivers include despreaders with rake capabilities to obtain enhanced output signals with multi-path reception. 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: A co-channel interference filter and a method for reducing co-channel interference for use in a television receiver. The television receiver receives a signal transmitted from a transmitter, the received signal having an encoded digital television signal component, a co-channel interference component, and a noise component, wherein the encoded digital television signal component is characterized as an N-level vestigial sideband (VSB) signal of Reed-Solomon (R-S) encoded, byte interleaved and trellis encoded symbols c.sub.k, i (for i=1 to 12), where N corresponds to a number of levels, and further wherein each symbol c.sub.k, i is derived from original symbol bits a.sub.k, i.sup.1 and a.sub.k, i.sup.2 (for i=1 to 12), respectively. The co-channel interference filter comprises a generator for generating a characteristic coefficient .alpha. in response to a received television signal, .alpha. being dependent upon an amount of the co-channel interference and noise components present in the received signal.

Abstract: A drawer guide for a pull-out component of a piece of furniture includes a carcass rail fixedly attachable to an inner side of the piece of furniture, a support rail for supporting the pull-out component, a middle rail arranged between the carcass and support rails and having at least two, arranged one above another, horizontal flanges which serve as tracks for a plurality of freely rotatable rollers, and at least one stop provided between the middle and support rails for limiting a pull-out path therebetween and projecting through a recess formed in the lower one of the two flanges, with the stop cooperating with a track roller provided on the rear end of the support rail.

Abstract: A television receiver for reducing a co-channel interference comprises a receiver for receiving a transmitted digital television signal having an encoded digital television signal component, a co-channel interference component, and a noise component, the receiver further providing a received output signal. A simplified rejection filter filters the received output signal to reduce the co-channel interference component thereof. The rejection filter comprises a simplified prediction filter having a fixed number L of tap coefficients z.sub.1, . . . , z.sub.L, wherein the number L is less than a number N of tap coefficients for an optimal prediction filter. The optimal prediction filter corresponds to a prediction filter implemented at a television transmitter for precoding the digital television signal prior to being transmitted by the television transmitter. The rejection filter means further provides a filtered output signal.

Abstract: A digital advanced television (ATV) receiver includes a multi-tap feedforward filter for reducing NTSC co-channel interference in a received ATV signal. A complementary Tomlinson precoder is used to compensate the transmitted ATV signal for inter-symbol interference (ISI) created in the receiver by the feedforward NTSC rejection filter. Data components of the transmitted signal are non-linearly precoded while synchronization components are linearly precoded to improve sync recovery S/N performance in the receiver.

Abstract: A receiver receives an ATV (e.g. HDTV) signal in an area that is subject to NTSC co-channel and other interference. The received signal is precoded at the transmitter for enabling reduction of NTSC co-channel interference in the received signal. The received signal includes field sync signals that are successively field combed to produce a subtraction signal. The subtraction signal is comb filtered to reduce NTSC co-channel interference and applied to a comparator along with the unfiltered subtraction signal. The comparator determines whether the level of NTSC co-channel interference is sufficiently great to subject the received ATV signal to comb filtering for reducing the NTSC co-channel interference.

Abstract: A technique for enhancing the robustness of an ATV transmission system in the presence of NTSC or ATV co-channel interference comprises positioning the ATV signal relative to the co-channel NTSC/ATV signal to reduce interference into the ATV receiver. In a preferred embodiment, the ATV signal is positioned relative to a co-channel NTSC signal such that the demodulated difference f.sub.v -f.sub.p in the ATV receiver is equal to 70.5 f.sub.seg, where f.sub.v is the NTSC visual carrier frequency, f.sub.p is the ATV pilot carrier frequency and f.sub.seg is the ATV segment repetition rate, and relative to a co-channel ATV signal such that their respective pilot frequencies differ by an amount equal to 1.5 f.sub.seg.

Abstract: The invention comprises an optimal causal, monic (first coefficient of filter is 1) NTSC rejection filter for use at an ATV receiver which is designed to optimally process the interference caused by an NTSC co-channel signal while keeping the noise enhancement to a desirably low value. In other words, the design method gives the filter with the BEST NTSC rejection capability for a given noise enhancement.

Abstract: A device and method for removing co-channel conventional television signal interference from a digital signal by using an adaptive filter which tunes to the periodic components of the conventional television signal. The output of the adaptive filter is then subtracted from the received signal to produce an error signal. This error signal is then used to recursively update the taps of the adaptive filter. The invention also relates to the use of the adaptive filter in conjunction with a DFE.

Abstract: An HDTV transmission system includes a Tomlinson precoder in the transmitter in order to compensate for forced intersymbol interference introduced by an NTSC rejection filter used in the receiver. The system employs one of a family of four-dimensional coded modulation schemes based on a six-signal-point, one-dimensional base constellation. The various schemes exhibit different amounts of so-called shaping gain and support respective different payload data rates. The characteristics of the Tomlinson precoder are such as to preserve the substantial portion of the shaping gain. The system may switch its operation among the various coded modulation schemes to account for changes in channel conditions and/or to accommodate different source signal bit rates.

Abstract: An NTSC interference detector is disclosed which includes an NTSC extracting filter for extracting an NTSC signal component from a received I-channel signal; a comparing portion for integrating the NTSC signal output from the NTSC extracting filter for a predetermined period and deciding whether the NTSC signal component is above a first reference value or not; and a control signal generator for adding the signal output from the comparing portion for every horizontal sync, deciding the presence or absence of NTSC interference according to a second reference value, and outputting a control signal according to the presence or absence of NTSC interference, thereby accomplishing a precise detection of NTSC interference.

Abstract: An ATV receiver having a decoder which is designed to process a subset limited trellis pre-coded television signal. The decoder processes co-channel interference so as to produce at the filter output of a rejection filter, a residual interference spectrum which is as flat as possible. The filter exploits the fact that only the picture and the sound carriers need to be sufficiently attenuated and cancels NTSC co-channel interference with only a small degradation in performance when AWGN is also present.

Abstract: A rejection filter for use at an ATV receiver which is designed to process co-channel interference so as to produce at the filter output of the filter, a residual interference spectrum which is as flat as possible. The filter exploits the fact that only the picture and the sound carriers need to be sufficiently attenuated and cancels NTSC co-channel interference with only a small degradation in performance when AWGN is also present.

Abstract: A frequency allocation is provided to minimize the effects of amplifier distortion in a mixed analog and digital cable television system. In particular, successive digital channel signals having a bandwidth substantially equal to .omega. are separated by a pair of adjacent analog channel signals, each having a bandwidth substantially equal to .omega.. In an illustrated embodiment, the analog and digital channel signals comprise amplitude modulated carriers having substantially equal power levels.

Abstract: A digital data transmission system for signals in the areas of interference having a high degree of vertical correlation comprises a transmission frame including a plurality of vertically arranged repetitive horizontal data segments each including a fixed number of subsegments with symbols of individual subsegments being vertically correlated on different data segments. The vertically correlated symbols are further interspersed in the transmission frame for guarding against horizontally correlated burst noise. A Reed-Solomon correction system is incorporated for each data segment in the transmission frame.

Abstract: A cochannel interference filter for a HDTV transmission system comprising a post-comb filter. The post-comb filter comprises first and second feedforward circuits. The first feedforward circuit includes a first adder and a first delay circuit. The first adder has a first input connected to an output of a data clock recovery circuit. The first delay circuit has an input connected to the output of the data clock recovery circuit and an output connected to a second input of the first adder. The second feedforward circuit includes a second adder and a second delay circuit. The second adder has a first input connected to an output of the first adder. The second delay circuit has an input connected to the output of the first adder and an output connected to a second input of the second adder. Also, the post-comb filter comprises third and fourth feedforward circuits. The third feedforward circuit includes a third adder and a third delay circuit.

Abstract: The proposed method of broadcasting television signals is such that the phase of the carrier signal as modulated with the video signal is shifted through 180.degree. from one line to the next within a field. Measure ensures that the disturbance signal due to a transmitter operating in the same channel will produce opposite effects from one line to the next, i.e. a brightening in one line and a darkening in the next. These opposite disturbances of adjacent lines are then compensated by the vision of the viewer or by electronic circuits specially designed for this purpose, so that the picture data originating from the interfering transmitter will not be perceived by the viewer.