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: 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: 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.

Abstract: Smoothing of regenerated digital pictures (e.g. after a heavy signal compression and coding for transmission on a narrowband medium) can be effected by means of a so-called "cosmetics filter" which filter comprises a digital lowpass filter, a delay, a subtraction unit, a table and an adder. An input signal enters the lowpass filter and the delay which is arranged in parallel with the lowpass filter. The difference between the delayed signal and the lowpass-filtered signal is used to address the table. An address content from the table is passed to the adder to be added to the lowpass-filtered signal from the lowpass filter, and the sum signal from the adder is the final filtered signal to the output from the cosmetics filter.

Abstract: A system for and method of enhancing image/video signals to be decoded is disclosed. The system for and method of post-filtering uses, preferably, a temporal filter and a spatial filter, both of which are adaptive but neither is required to be adaptive. However, the system for and method of post-filtering may also be used with only an adaptive spatial post-filter. In this case, the performance is upper-bounded by the performance of systems using both the adaptive temporal and adaptive spatial post-filter.

Abstract: An image processing system uses a pseudo-random pixel interlace method and apparatus for capturing groups of pixels as image frames. This pseudo-random method eliminates the artifacts commonly present in standard regular line raster scan imaging systems. Moreover, the pixel interlacing method permits the construction of higher resolution frames from a series of orthogonal lower resolution frames. An enhancement circuit deduces information from previous pixel group frames and contributes additional detail to the pixels of the frame being processed. The format of the pixel interlaced groups permits the present invention to be used in a wide variety of normally incompatible target display rates. The present invention can also be used in a computing system as an auto-synchronizer for processing signals from different sources.

Abstract: A cable transmission system transmits television signals in a family of M-level symbol data constellations. Lower frequency ones of the television signals are transmitted in data constellations of relatively higher values of M and higher frequency ones of the television signals are transmitted in data constellations of relatively lower values of M to optimize signal to noise performance and spectrum utilization.

Abstract: A vestigial-sideband amplitude-modulation transmitter using a balanced modulator for generating a suppressed carrier that is in quadrature phasing with the video carrier of a television signal receives as modulating signal a binary phase-shift-keying (BPSK) signal encoding digital signals. The quadrature transmission reduces the visibility of the lower-frequency PSK sidebands in the TV signal as viewed on screen. The symbol rate of the PSK is made to be a multiple of the horizontal line scan rate of video signal. To reduce the visibility of the higher-frequency PSK sidebands in the TV signal as viewed on screen, the BPSK is transmitted twice during respective frames of successive pairs of data frames, which data frames recur at the same rate as video frames. To reduce the interference of video with the BPSK, the BPSK is comb filtered at the digital signal receiver and after symbol detection is subjected to partial-response filtering for recovering the digital signal originally encoded in the BPSK signal.

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: At least a first and a second digital signal, both in parallel form, are converted to a single serial signal and transmitted from a digital color decoder to a signal processing unit so as to avoid picture disturbances in the signal processing unit. The first digital signal is dependent on the instantaneous value of a clock frequency used in the decoder for processing a digital color picture signal, and the second digital signal is dependent on the instantaneous value of a chrominance subcarrier frequency generated in the decoder and used for color decoding.

Abstract: In a video signal processing system, a single adaptive passband equalizer is used to process a composite Quadrature Amplitude Modulated (QAM) signal encoded with high priority (HP) and standard priority (SP) components. The equalizer output is phase corrected by a de-rotator, and filtered to separate the HP and SP components. Error signals respectively representing HP and SP phase errors are developed. One of the error signals controls the operation of the de-rotator. Both error signals are used to generate updated coefficients for the adaptive equalizer. Afterwards the HP and SP components are decoded and combined.

Abstract: A television signal receiver processes a television signal representing a letterbox image display format with a main image region, and a bar region containing auxiliary information to help convert from interlaced to progressive scanning. The auxiliary information is processed in a signal path including a nonlinear amplitude expander and apparatus for modifying the operation of the signal path as a function of the noise content of the television signal.

Abstract: Encoded blocks of video information are selected for transmission at a plurality of channel rates based on the corresponding location of the portions of the video image represented by the encoded blocks. Each encoded block is designated an image type which determines its transmitted channel rate. The image types are associated with spatial positions of a video image such that encoded blocks within a first area of the video image are designated a first image type and encoded blocks within a second area of the image are designated a second image type. In general, data blocks representing the central portion of the video image are transmitted at a channel rate having less susceptibility to noise or other degradation, thereby ensuring that such portion can be received in fringe areas.