초록 ▼

A method and apparatus for communicating high definition television signals is provided. Video signals are divided into blocks of PCM data. The PCM data is processed using motion estimation and compensation to provide DPCM data. For each block, one of PCM and DPCM data is selected for transmission b

A method and apparatus for communicating high definition television signals is provided. Video signals are divided into blocks of PCM data. The PCM data is processed using motion estimation and compensation to provide DPCM data. For each block, one of PCM and DPCM data is selected for transmission based on a predetermined criteria. The selected data is compressed using the discrete cosine transform to provide blocks of transform coefficients. The coefficients are quantized to improve their coding efficiency and variable length coded. The variable length coded coefficients are coded using a concatenated coding scheme with a Reed-Solomon outer code and trellis inner code to provide coded signals for transmission. The coded signals are transmitted using QAM.

대표청구항 ▼

1. A method for communicating digital television signals comprising the steps of: dividing video portions of said digital television signals into blocks of pulse code modulated (PCM) video data; processing said blocks of PCM video data using motion estimation and compensation to provide correspo

1. A method for communicating digital television signals comprising the steps of: dividing video portions of said digital television signals into blocks of pulse code modulated (PCM) video data; processing said blocks of PCM video data using motion estimation and compensation to provide corresponding differential pulse code modulated (DPCM) data; selecting either the PCM video data or the corresponding DPCM data for transmission based on a predetermined criterion; compressing the selected data using the discrete cosine transform to provide blocks of transform coefficients; quantizing the transform coefficients in said blocks of transform coefficients to improve the coding efficiency thereof; variable length coding said quantized transform coefficients; coding said variable length coded quantized transform coefficients using a concatenated coding scheme with a Reed-Solomon outer code and a trellis inner code to provide coded signals for transmission; transmitting said coded signals as quadrature amplitude modulation (QAM) symbols from an N-point QAM constellation pattern having four subsets, each subset being identified by a different two-bit codeword and including N/4 symbol points of said N-point QAM constellation pattern; wherein said trellis inner code encodes a symbol from said Reed-Solomon outer code by processing a first bit of said symbol with a rate 1/2 binary convolutional encoding algorithm to provide the two-bit codeword assigned to the subset in which said symbol resides in said N-point QAM constellation pattern, and said two-bit codeword is mapped with remaining bits of said symbol to provide a modulation function for transmission on a carrier, said remaining bits correlating said symbol with one of the N/4 symbol points included in the subset defined by said two-bit codeword; receiving said carrier at a receiver; demodulating the received carrier at said receiver to recover said modulation function; providing, form the recovered modulation function, a set of metrics corresponding to said subsets and a plurality of bytes representing different conditional determinations of a signal point identified by the remaining bits; using said metrics in a trellis code algorithm for decoding a rate 1/2 binary convolutional code to recover said first bit; encoding the recovered first bit using a rate 1/2 binary convolutional encoding algorithm to recreate said two-bit codeword; selecting one of said conditional determination bytes in response to said recreated two-bit codeword; and combining said selected byte with the recovered first bit to provide a decoded output. 2. A method in accordance with claim 1 wherein said concatenated coding scheme includes the steps of: interleaving symbols produced by said Reed-Solomon outer code, according to a first interleave format, to disperse burst errors that may be subsequently generated by the trellis inner code; and interleaving the coded signals produced by said trellis inner code, according to a second interleave format, to disperse burst errors that may be subsequently generated along a transmission path for said coded signals. 3. A method in accordance with claim 1 wherein: said two-bit codeword forms the least significant bits of said modulation function; and said remaining bits form the most significant bits of said modulation function. 4. A method in accordance with claim 2 further comprising the steps of: deinterleaving the recovered modulation function using the converse of the second interleave format; deinterleaving the decoded output using the converse of the first interleave format; and decoding the deinterleaved decoded output using a Reed-Solomon symbol error correcting decoding algorithm. 5. A method in accordance with claim 4 wherein said Reed-Solomon decoding algorithm recovers variable length coded coefficients from the deinterleaved decoded output, said method further comprising the steps of: decoding said recovered variable length coded coefficients to recover transform coefficients representative of said video portions; inverse transforming the recovered transform coefficients to recover video data in or DPCM format; processing recovered DPCM data using motion compensation to recover PCM video data represented by the recovered DPCM data; and formatting the recovered PCM video data for output to a digital television receiver. 6. A method for decoding digital television signals containing compressed video information and transmitted using quadrature amplitude modulation, comprising the steps of: receiving a carrier containing said digital television signals; demodulating the received carrier to recover an interleaved modulation function containing said compressed video information; deinterleaving the recovered modulation function; decoding the deinterleaved modulation function in an inner trellis decoding algorithm of a concatenated decoder to recover interleaved Reed-Solomon symbols representative of the compressed video information; deinterleaving the recovered Reed-Solomon symbols for input to an outer Reed-Solomon decoding algorithm of said concatenated decoder, said Reed-Solomon decoding algorithm recovering variable length coded coefficients from the deinterleaved Reed-Solomon symbols; decoding said recovered variable length coded coefficients to recover transform coefficients representative of said compressed video information; inverse transforming the transform coefficients to recover video data in a pulse code modulated (PCM) or differential pulse code modulated (DPCM) format; processing recovered DPCM data using motion compensation to recover PCM video data represented by the recovered DPCM data; and formatting the recovered PCM video data for output to a digital television receiver, wherein said modulation function comprises an N-bit QAM modulation function in which a two-bit codeword identifies one of a plurality of QAM constellation subsets and the remaining N-2 bit portion represents a signal point within said one subset, said method further comprising the steps of: pruning the recovered modulation function to provide a set of metrics corresponding to said subsets and to provide a plurality of N-2 bit subgroups representing a plurality of conditional determinations of the signal point identified by the N-2bit portion; using said metrics in said trellis decoding algorithm to decode a rate 1/2 binary convolutional code to recover a first bit; encoding the recovered first bit using a rate 1/2 binary convolutional encoding algorithm to recreate said two-bit codeword; selecting one of said plurality of N-2 bit subgroups in response to said recreated two-bit codeword; and combining the selected subgroup with the recovered first bit to provide a Reed-Solomon symbol. 7. A method in accordance with claim 6 wherein: said two-bit codeword forms the least significant bits of said modulation function; and said remaining bits form the most significant bits of said modulation function. 8. Apparatus for communicating digital television signals comprising: means for processing blocks of pulse code modulated (PCM) video data using motion estimation and compensation to provide corresponding differential pulse code modulated (DPCM) data; means for comparing said PCM video data to the corresponding DPCM data provided by said processing means and for selecting one of PCM video data or DPCM data for transmission based on a predetermined criterion; means for compressing the selected data using the discrete cosine transform to provide blocks of transform coefficients; means for quantizing said blocks of transform coefficients to improve the coding efficiency thereof; means coupled to an output of said quantizing means for variable length coding said transform coefficients; a concatenated coder including a Reed-Solomon outer coder and a trellis inner coder for coding said variable length coded transform coefficients to provide coded signals for transmission; and means for transmitting said coded signals as quadrature amplitude modulation (QAM) symbols from an N-point QAM constellation pattern having four subsets, each subset being identified by a different two-bit codeword and including N/4 symbol points of said N-point QAM constellation pattern; wherein said trellis inner coder encodes symbol from said Reed-Solomon outer coder by processing a first bit of said symbol with a rate 1/2 binary convolutional encoding algorithm to provide the two-bit codeword assigned to the subset in which said symbol resides in said constellation pattern; said two-bit codeword is mapped with remaining bits of said symbol to provide a modulation function, said remaining bits correlating said symbol with one of the N/4 symbol points included in the subset defined by said two-bit codeword; and said transmitting means modulate said modulation function onto a carrier, said apparatus further comprising: means for receiving said carrier at a receiver; means for demodulating said received carrier to recover said modulation function; means for pruning the modulation function to provide a set of metrics corresponding to said subsets and to provide a plurality of bytes representing different conditional determinations of a signal point identified by the remaining bits; trellis decoder means coupled to receive said metrics for use in decoding a rate 1/2 binary convolutional code to recover said first bit; means for encoding the recovered first bit using a rate 1/2 binary convolutional encoding algorithm to recreate said two-bit codeword; means for selecting one of said conditional determination bytes in response to said recreated two-bit codeword; and means for combining said selected byte with the recovered first bit to provide a decoded output. 9. Apparatus in accordance with claim 8 wherein said concatenated coder comprises: a first interleaver for interleaving symbols produced by said Reed-Solomon outer code in accordance with a first interleave format, to disperse burst errors that may be subsequently generated by the trellis inner code; and a second interleaver for interleaving the coded signals produced by said trellis inner code in accordance with a second interleave format, to disperse burst errors that may be subsequently generated along a transmission path for said coded signals. 10. Apparatus in accordance with claim 8 wherein: said two-bit codeword forms the least significant bits of said modulation function; and said remaining bits form the most significant bits of said modulation function. 11. Apparatus in accordance with claim 9 further comprising: means for deinterleaving the recovered modulation function using the converse of the second interleave format; means for deinterleaving the decoded output using the converse of the first interleave format; and means for decoding the deinterleaved decoded output using a Reed-Solomon symbol error correcting decoding algorithm. 12. Apparatus in accordance with claim 11 wherein said means for decoding using the Reed-Solomon decoding algorithm recovers variable length coded coefficients from the deinterleaved decoded output, said apparatus further comprising: means for decoding said recovered variable length coded coefficients to recover transform coefficients; means for inverse transforming the recovered transform coefficients to recover video data in at least one of a PCM or DPCM format; means for processing recovered DPCM data using motion compensation to recover PCM video data represented by the recovered DPCM data; and means for formatting the recovered PCM video data for output to a digital television receiver. 13. Apparatus for decoding digital television signals containing compressed video information and transmitted using quadrature amplitude modulation (QAM), comprising: means for receiving said digital television signals; a QAM demodulator for demodulating a carrier containing said digital television signals to recover an interleaved modulation function containing said compressed video information; a first deinterleaver for deinterleaving the recovered modulation function; a concatenated decoder for decoding the deinterleaved modulation function using an inner trellis decoder to recover interleaved Reed-Solomon symbols representative of the compressed video information; a second deinterleaver for deinterleaving the recovered Reed-Solomon symbols for input to an outer Reed-Solomon decoder of said concatenated decoder, said Reed-Solomon decoder recovering variable length coded coefficients form the deinterleaved Reed-Solomon symbols; means for decoding said recovered variable length coded coefficients to recover transform coefficients representative of said compressed video information; means for inverse transforming the recovered transform coefficients to recover video data in a pulse code modulated (PCM) or differential pulse code modulated (DPCM) format; means for processing recovered DPCM data using motion compensation to recover PCM video data represented by the recovered DPCM data; and means for formatting recovered PCM video data for output to a digital television receiver; wherein said modulation function comprises an N-bit QAM modulation function in which a two-bit codeword identifies one of a plurality of QAM constellation subsets and the remaining N-2 bit portion represents a signal point within said one subset, said apparatus further comprising: means for pruning the recovered modulation function to provide a set of metrics corresponding to said QAM constellation subsets and to provide a plurality of N-2 bit subgroups representing a plurality of conditional determinations of the signal point identified by the N-2 bit portion; said concatenated decoder being coupled to receive said set of metrics for use in said trellis decoder to decode a rate 1/2 binary convolutional code to recover a first bit; means for encoding the recovered first bit using a rate 1/2 binary convolutional encoding algorithm to recreate said two-bit codeword; means for selecting one of said plurality of N-2 bit subgroups in response to said recreated two-bit codeword; and means for combining the selected subgroup with the recovered first bit to provide a Reed-Solomon symbol. 14. Apparatus in accordance with claim 13 further comprising: an adaptive equalizer coupled between said QAM demodulator and said concatenated decoder. 15. Apparatus for decoding transmitted digital signals to recover information therefrom, comprising: means for receiving a carrier containing said transmitted digital signals; a demodulator coupled to said receiving means for demodulating the received to recover a modulation function; a concatenated decoder comprising an inner trellis decoder and an outer Reed-Solomon decoder for decoding the modulation function, said inner trellis decoder recovering Reed-Solomon symbols representative of said information and said outer Reed-Solomon decoder recovering variable length codes from the Reed-Solomon symbols; and means for decoding said recovered variable length codes to recover said information; wherein: said modulation function is an N-bit modulation function in which a two-bit codeword identifies one of a plurality of constellation subsets and the remaining N-2 bit portion represents a signal point within said one subset; and said concatenated decoder comprises: means for pruning the recovered modulation function to provide a set of metrics corresponding to said constellation subsets and to provide a plurality of N-2 bit subgroups representing a plurality of conditional determinations of the signal point identified by the N-2 bit portion, said inner trellis decoder using said st of metrics to decode a rate 1/2 binary convolutional code to recover a first bit; means for encoding the recovered first bit using a rate 1/2 binary convolutional encoding algorithm to recreate said two-bit codeword; means for selecting one of said plurality of N-2 bit subgroups in response to said recreated two-bit codeword; and means for combining the selected subgroup with the recovered first bit to provide a Reed-Solomon symbol. 16. Apparatus in accordance with claim 15 further comprising: a first deinterleaver for deinterleaving the recovered Reed-Solomon symbols for input to said outer Reed-Solomon decoder. 17. Apparatus in accordance with claim 16 wherein said information comprises video information.