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: 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 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 system for transmitting and receiving digital data which utilizes pre-coding at a transmitter, and selects post-coding at a receiver when co-channel interference not present or post-comb processing at the receiver when co-channel interference is present. The system includes a symbol interleaver at the transmitter and a symbol deinterleaver at the receiver which minimizes the byte errors by organizing the data input at the pre-coder at the transmitter such that the symbol errors and their respective propagated errors are re-organized so as to be disposed adjacent to each other, thereby forming adjacent symbol errors. The effect of this re-organization is to increase the probability that each pair of adjacent symbol errors correspond to bits which lie in the same byte.

Abstract: Video signal encoding apparatus, suitably for multiple video channels (A,B) has respective encoder stages (10,12) which encode a received video signal according to a predetermined coding scheme, such as MPEG standard, and output a variable bit-rate data stream to encoder channel buffering (16) which is combined in a single buffer (16) having a fixed physical size with separate portions assigned to each channel. Buffer management (18) varies the size of the effective buffer areas assigned to the respective channels to maintain the total effective buffer area close to but within the physical limits of the buffer, as defined by the overall sum of encoder output bit rates. The outputs of the encoder buffer are combined into a single data stream, suitably by multiplexing (28), for subsequent separation and decoding by a receiver (30 to 36).

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 method and apparatus for transmitting a digital television signal using a first multipoint constellation comprised of a plurality of identical second constellations each having fewer points than the first constellation and each positioned in a different section of the first constellation. The receiver includes a decoder which decodes data as encoded in one of the second constellations. Additional bits, transmitted with the data, are also decoded at the receiver to identify which to section of the first constellation the second constellation belongs.

Abstract: A method and apparatus for transmitting a digital television signal using a single QAM (quadrature amplitude modulated) carrier which provides audio and video data packets at respective complex symbol data rate levels. One purpose of the invention is to provide a digital television signal which resembles the audio vs. video reception characteristics exhibited by conventional analog television (i.e. NTSC). way communication path.

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 method and apparatus for modulating and demodulating an MCM television signal is described which is particularly useful in proposed "simulcast" HDTV terrestrial broadcasting. The MCM spectrum of the television signal is shaped using weighting coefficients which are derived from either an idealized NTSC signal or an actual NTSC co-channel signal. These coefficients are used to shape the respective MCM carriers to provide an energy distribution in the MCM signal which provides greater degree of robustness with a minimum degree of co-channel interference to and from an NTSC co-channel signal. The instant invention further takes advantage of the interference characteristics of composite television signals described above, to position the placement of the MCM carriers in frequency, to minimize interference with an NTSC co-channel signal.