Philips Electronics North America Corporation

U.S. Philips Corporation

Monisha Ghosh

Samir N Hulyalkar

Aldo G Cugnini

A method and device for improving the reception of a vestigial-sideband (VSB) signal by reducing the loss of information at the band edges in severe multipath. This is achieved by using complex equalization in conjunction with real equalization, in which any band-edge distortion is equalized by the complex equalization.

VSB receiver with complex equalization for improved multipath performance

A digital receiver (e.g., an ATV or HDTV receiver) which receives digital signals (e.g., ATV or HDTV signals), and which includes an equalizer for equalizing multipath channels having known co-channel interference (e.g., co-channel NTSC interference) present therein. A co-channel interference rejection filter is inserted in the digital receiver upstream of the equalizer, and the equalizer is modified in such a manner that it will not attempt to equalize the co-channel interference. Thus, co-channel interference cancellation is done primarily by the rejection filter, while multipath equalization (correction) is the exclusive function of the equalizer. This leads to better co-channel performance than that which can be obtained by relying on the equalizer alone to perform both functions. The co-channel interference rejection filter is preferably a multi-tap filter having fixed filter coefficients which are designed to optimize cancellation of the known co-channel interference.

Digital receiver which utilizes a rejection filter for cancellation of known co-channel interference and an equalizer for equalizing multipath channels without attempting to equalize the co-channel interference

A blind equalization method and adaptive filter device is presented which provides for optimal performance with minimal computational complexity. Recognizing that all realizable filters have residual noise characteristics, the optimization of a hard-limiter adaptive filter is determined in dependence upon an estimate of this noise characteristic. The filter can be further adapted and optimized in dependence upon measured values of the filter's noise characteristics in its actual operating environment.

Blind equalization method and apparatus having reduced complexity

In a CATV return channel between a transmitter and a headend receiver, the transmitter is provided with a precoder having programmable but fixed coefficients. The receiver is provided with an ingress rejection filter (IRF) having programmable but fixed coefficients. A non-precoded training sequence is sent from the transmitter to the receiver during a training interval. A multipath and an ingress in the CATV return channel are estimated at the receiver based upon the training sequence sent by the transmitter and received by the receiver. The precoder coefficients and the IRF coefficients are calculated and the precoder and the ingress rejection filter are programmed with the calculated coefficients, respectively. The precoder and the ingress rejection filter use the respective calculated coefficients during a data transmission interval to simultaneously compensate for undesirable effects of multipath and ingress noise in the CATV return channel during data transmission from the transmitter to the headend.

Method and apparatus for combatting ingress and multipath in a CATV

A blind-equalization method and apparatus are disclosed for equalization of a channel of an HDTV receiver. The HDTV receiver comprises a rejection filter corresponding to a precoder for which precoding is implemented at a television transmitter for combating co-channel interference, wherein the television transmitter transmits a digital television signal. The HDTV receiver further comprises an equalizer having an input and an output. The equalization method comprises the steps of initiating an equalization with a blind slicing mode. The method further comprises changing the equalization to a training sequence mode upon an occurrence of a no flutter condition. While in the training sequence mode, if a flutter condition occurs, then the equalization is returned to the blind slicing mode. A determination of the occurrence of the flutter condition is based upon an estimate of a negative derivative of the Signal-to-Noise Ratio (SNR) at the output of the equalizer, dS.sub.o, being greater than a prescribed threshold.

Blind equalizer method and apparatus for HDTY transmission using an NTSC

A transmitter-receiver system and a method for transmitting and receiving MCM signals, whereby any frequency offset and timing mismatch can be determined and corrected simultaneously, prior to demodulating the received signal. A plurality of single tone signals are transmitted prior to the transmission of the symbols corresponding to the desired information. The receiver is outfitted with a Frequency Offset and Timing Estimator for receiving theme plurality of single tone signals, estimating any frequency offset and timing mismatch and correcting the sampler and sampled signal accordingly, prior to demodulating the sampled signal.

Method and apparatus for joint frequency offset and timing estimation of

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.

Receiver based methods and devices for combating co-channel NTSC

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. The filter block provides a filtered output signal. A detector, responsive to the received output signal, is provided for detecting information regarding the precoder. The detector includes a selector for selecting the desired one of the plurality of rejection filters in response to the detected information, and provides the selection control signal for the filter block. Lastly, a device, responsive to the filtered output signal, produces a decoded digital television signal.

Method and apparatus for combating co-channel NTSC interference for

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.

Method and apparatus for optimal NTSC rejection filtering and

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.

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Mohegan Lake, NY, United States of America

Monisha Ghosh