General Electric Company

Sarnoff Corporation

Rca Licensing Corporation

Krishnamurthy Jonnalagadda

Liston Abbott

James J Gibson

Robert E Flory

James M Walter

Edward Coley Fox

Theodor M Wagner

Allan A Guida

Error correction in a data transmission system transmitting data as a sequence of data packets, each data packet containing a number of data bytes, employs parity bytes generated for each data byte in each data packet (e.g., row parity bytes) in conjunction with parity bytes for certain data bytes in predetermined data byte positions over a number of data packets (column data bytes). In a transmission arrangement, row parity bytes are generated and transmitted in a principal data channel along with the data packets, and column parity bytes are generated and transmitted in an ancillary data channel. In a receiver arrangement, row parity bytes are decoded in a principal data channel along with the data packets, and column parity bytes are decoded in an ancillary data channel and are employed to correct the data bytes in the principal data channel. A transmission system includes a transmission arrangement and a receiver arrangement communicating via a transmission medium.

Forward error correction for video signals

A method and apparatus for recovering an information carrier which has been transmitted as a sub-carrier in the lower VSB spectral region of a television signal. The invention utilizes a spectral inversion method to shift the data carrier frequency from the normal VSB spectral region to a spectral region normally associated with video information in a standard television signal. The data carrier is then recovered using a standard video demodulator and provided to a data utilization circuit, such as a QPSK demodulator.

Recovering data from a vestigial sideband of a standard television signal

A method and apparatus for reducing video crosstalk in a data carrier located within a lower vestigial sideband (VSB) of a standard television signal. Specifically, an apparatus according to the invention comprises a single bandpass filter for conditioning a VSB television signal, and a frequency interleaver for spectrally adding the data carrier to the lower VSB of the standard VSB video signal. The filter removes removing video components from the lower VSB of a standard VSB video signal, including frequencies greater than the highest frequency nominally associated with the lower VSB of the standard television signal, illustratively 250 Khz above the nominal VSB bandedge. The filter also boosts frequencies in a spectral boost region within a passband for boosting region. The boosted frequencies comprise image frequencies associated with the non-VSB spectrum attenuated by the filter. The compensation is required to ensure that the above image frequencies are not over-attenuated by a standard television receiver Nyquist filter.

Reducing video crosstalk in a data carrier located within a vestigial

An encoding scheme resistant to transmission errors encodes a data bitstream for application to a quadrature amplitude modulator (QAM) in a high definition television system. The error-resistant code provides a rotationally symmetrical 32-point constellation on a plane defined by I,Q quadrature axes. The constellation is divided into first and second partitions arranged so that constellation points that are closest in distance to any constellation point of the first partition belong to the second partition, and constellation points that are closest in distance to any constellation point of the second partition belong to the first partition. The binary value of one bit of each of successive 9-bit packets in the bitstream determines that one of the two partitions to which both of a consecutive pair of first and second constellation-point transmissions belong (the first and second transmitted constellation-points of that consecutive pair being selected by the then current 9-bit packet of the stream). The code is such that the binary values of such one bit of each of alternate ones of the successive 9-bit packets are opposite to one another. This permits a receiver decoder to decide whether each received constellation-point belongs to a first or a second constellation, thereby permitting the detection and, in most cases, the correction of transmission errors.

QAM encoding for high-definition television system

High definition or enhanced television signals include supplementary information which is double-sideband modulated in quadrature with the picture carrier, and passed through an inverse Nyquist filter before being combined with a conventional vestigial sideband modulated main video signal. A receiver which recovers both the main video signal and the supplementary information processes the received video signal through an IF filter having a vestigial sideband frequency response characteristic. Two synchronous detectors recover in-phase and quadrature phase signal components from the filtered television signals, these recovered signals each include quadrature crosstalk distortion components from the other signal. The crosstalk from the supplementary signal into the main signal is canceled by filtering the recovered quadrature signal and adding the result to the recovered in-phase signal. This filtering also equalizes the in-phase signal by converting the quadrature distortion components in the recovered quadrature signal into reenforcing signal components in the in-phase signal. This signal recovery system is advantageously used with a ghost cancellation system.

Method and apparatus for canceling quadrature distortion as for video

A system for transmitting digital sound signals in a standard broadcast video signal includes apparatus for removing video signals from a portion of the vestigial sideband of the broadcast video signal and inserting coded digital sound signals therein.

Apparatus for incorporating digital signals with a standard TV signal

Apparatus for augmenting a television signal with auxiliary signal includes circuitry for modulating a picture carrier with baseband video signal to generate a vestigial sideband television signal. Auxiliary signal is modulated on a further carrier of such frequency that the upper sidebands of the modulated further carrier, representing the auxiliary information, (1) occupy the frequency spectrum of the vestigial sideband of the vestigial sideband television signal and (2) occur clustered at odd multiples of half line frequency. The sidebands of the modulated further carrier are added to the vestigial sideband television signal in frequency interleaved fashion in the vestigial sideband spectral region.

Method of transmitting auxiliary information in a television signal

Extended definition television (EDTV) signals including a compatible composite wideband signal and a separate helper or extended definition signal are combined, for example, for recording purposes, using frequency multiplexing techniques. The helper signal is applied to a modulator, which produces a suppressed carrier modulated signal, to frequency shift the helper signal to a spectral band above the frequency band occupied by the compatible composite wideband signal. The frequency shifted and wideband signal are then added to form the combined signal.

Growing community of inventors

Plainsboro, NJ, United States of America

Krishnamurthy Jonnalagadda