Repetitive-PN1023-sequence echo-cancellation reference signal for single-carrier digital television broadcast systems

A receiver for digital television signals broadcast in accordance with the method of claim said receiver comprising:

• front-end circuitry for supplying an amplified intermediate-frequency signal responsive to a radio-frequency broadcast digital television signal selected for reception;
• demodulator and analog-to-digital conversion circuitry for recovering a digitized baseband broadcast digital television signal from said amplified intermediate-frequency signal, said demodulator and analog-to-digital conversion circuitry connected for receiving said amplified intermediate-frequency signal from said front-end circuitry;
• gating circuitry for selectively reproducing a respective set of successive digital samples of 1023 symbol epochs duration from a selected cycle of each occurrence of said repetitive PN1023 sequence in the digitized baseband broadcast digital television signal recovered by said demodulator and analog-to-digital conversion circuitry, said selected cycle being sufficiently delayed from the beginning of said repetitive PN1023 sequence to be less affected by post-echoes of signal preceding said repetitive PN1023 sequence, and said selected cycle being sufficiently before the conclusion of said repetitive PN1023 sequence to be less affected by pre-echoes of signal succeeding said repetitive PN1023 sequence;
• DFT computer apparatus for computing the discrete Fourier transform of the power spectrum of said respective set of successive digital samples of 1023 symbol epochs duration;
• circuitry for generating a discrete Fourier transform characterizing the actual transmission channel by determining the quotient of
• each term of said discrete Fourier transform of the power spectrum of said respective set of successive digital samples of 1023 symbol epochs duration that said DFT computer apparatus computes, and
• the corresponding term of a discrete Fourier transform indicative of the response of an ideal transmission channel to the selected cycle of said repetitive PN1023 sequence;
• inverse-discrete-Fourier-transform circuitry for computing the inverse-Fourier transform of said discrete Fourier transform characterizing said actual transmission channel;
• adaptive channel-equalization and echo-cancellation filtering connected for responding to said digitized baseband broadcast digital television signal with a response that is adapted by adjustment of the weighting coefficients of said adaptive channel-equalization and echo-cancellation filtering in response to said inverse-Fourier transform;
• a trellis decoder for decoding the response of said adaptive channel-equalization and echo-cancellation filtering to recover interleaved data;
• a convolutional de-interleaver connected for de-interleaving the interleaved data recovered by said symbol decoder to generate packets of de-interleaved data;
• error-detection-and-correction circuitry connected for detecting any errors in each of said packets of dc-interleaved data, said error-detection-and-correction circuitry connected for supplying said packets of de-interleaved data with each one of said packets that had fewer than a prescribed number of errors having been corrected;
• a data de-randomizer connected for receiving from said error-detection-and-correction circuitry said packets of de-interleaved data with each one of said packets that had fewer than a prescribed number of errors having been corrected, and for generating a data de-randomizer output signal by exclusive-ORing said de-interleaved data with a prescribed de-randomizing signal;
• and
• a packet sorter connected for supplying in each of a plurality of output signals therefrom a particular set of identifiable data packets sorted from said data de-randomizer output signal in response to a packet identification signal for each data packet therein not left in error by said error-detection-and-correction circuitry.

A receiver for digital television signals broadcast in accordance with the method of claim said receiver comprising:

• front-end circuitry for supplying an amplified intermediate-frequency signal responsive to a radio-frequency broadcast digital television signal selected for reception;
• demodulator and analog-to-digital conversion circuitry for recovering a digitized baseband broadcast digital television signal from said amplified intermediate-frequency signal, said demodulator and analog-to-digital conversion circuitry connected for receiving said amplified intermediate-frequency signal from said front-end circuitry;
• auto-correlation filtering apparatus of non-cyclical type, connected for performing linear convolution of a single cycle of a reference PN1023 sequence with said digitized baseband broadcast digital television signal, to supply a correlation result containing a set of repeated cepstrums in response to the first portion of each said data field;
• circuitry for reproducing one cepstrum from each said repeating cepstrum, thereby to supply a separated cepstrum;
• adaptive channel-equalization and echo-cancellation filtering connected for responding to said digitized baseband broadcast digital television signal with a response that is adapted by adjustment of the weighting coefficients of said adaptive channel-equalization and echo-cancellation filtering in response to ones of said separated cepstrums;
• a symbol decoder for decoding the response of said adaptive channel-equalization and echo-cancellation filtering to recover interleaved data;
• a convolutional de-interleaver connected for de-interleaving the interleaved data recovered by said symbol decoder to generate packets of de-interleaved data;
• error-detection-and-correction circuitry connected for detecting any errors in each of said packets of de-interleaved data, said error-detection-and-correction circuitry connected for supplying said packets of de-interleaved data with each one of said packets that had fewer than a prescribed number of errors having been corrected;
• a data de-randomizer connected for receiving from said error-detection-and-correction circuitry said packets of de-interteaved data with each one of said packets that had fewer than a prescribed number of errors having been corrected, and for generating a data de-randomizer output signal by exclusive-ORing said de-interleaved data with a prescribed de-randomizing signal;
• and
• a packet sorter connected for supplying in each of a plurality of output signals therefrom a particular set of identifiable data packets sorted from said data de-randomizer output signal in response to a packet identification signal for each data packet therein not left in error by said error-detection-and-correction circuitry.

A receiver for broadcast digital television signals that periodically include a repetitive pseudo-random noise sequence said receiver comprising:

• front-end circuitry for supplying an amplified intermediate-frequency signal responsive to a radio-frequency broadcast digital television signal selected for reception;
• demodulator and analog-to-digital conversion circuitry for recovering a digitized baseband broadcast digital television signal from said amplified intermediate-frequency signal, said demodulator and analog-to-digital conversion circuitry connected for receiving said amplified intermediate-frequency signal from said front-end circuitry;
• auto-correlation filtering apparatus, connected for performing a circular convolution of a single cycle of a reference pseudo-random noise sequence with a selected single cycle of repetitive pseudo-random noise sequence from each occurrence of said repetitive pseudo-random noise sequence in said digitized baseband broadcast digital television signal from said demodulator and analog-to-digital conversion circuitry, thereby to generate a cepstrum characterizing the transmission channel to said receiver for digital television signalssaid selected single cycle being sufficiently delayed from the beginning of said repetitive pseudo-random noise sequence to be less affected by post-echoes of signal preceding said repetitive pseudo-random noise sequence, and said selected single cycle being sufficiently before the conclusion of said repetitive pseudo-random noise sequence to be less affected by pre-echoes of signal succeeding said repetitive pseudo-random noise sequence;
• and
• adaptive channel-equalization and echo-cancellation filtering connected for responding to said digitized baseband broadcast digital television signal with a response that is adapted by adjustment of the weighting coefficients of said adaptive channel-equalization and echo-cancellation filtering in response to said cepstrum.

A receiver for broadcast digital television signals that periodically include a repetitive pseudo-random noise sequence, said receiver comprising:

• front-end circuitry for supplying an amplified intermediate-frequency signal responsive to a radio-frequency broadcast digital television signal selected for reception;
• demodulator and analog-to-digital conversion circuitry for recovering a digitized baseband broadcast digital television signal from said amplified intermediate-frequency signal, said demodulator and analog-to-digital conversion circuitry connected for receiving said amplified intermediate-frequency signal from said front-end circuitry;
• a direct-component-suppression filter connected to receive as its input signal said digitized baseband broadcast digital television signal from said demodulator and analog-to-digital conversion circuitry, said direct-component-suppression filter connected to supply a response to said digitized baseband broadcast digital television signal that suppresses any direct component thereof;
• auto-correlation filtering apparatus of non-cyclical type, connected for performing a linear convolution of a single cycle of a reference pseudo-random noise sequence with each occurrence of said repetitive pseudo-random noise sequence in said response of said direct-component-suppression filter, thereby to generate a correlation result;
• a comb filter connected to receive as its input signal said correlation result and to supply a comb filter response which differentially combines said correlation result with itself as delayed by the duration of one cycle of said repetitive pseudo-random noise sequence, said comb filter response including an extended cepstrum characterizing the transmission channel to said receiver for digital television signals, which extended cepstrum is generated responsive to the consecutive cycles of said repetitive pseudo-random noise sequence in each data field;
• an extended-cepstrum register connected for selecting from said comb filter response the extended cepstrum generated to the consecutive cycles of said repetitive pseudo-random noise sequence in each data field, to be temporarily stored in said extended-cepstrum register;
• and
• adaptive channel-equalization and echo-cancellation filtering connected for responding to said digitized baseband broadcast digital television signal with a response that is adapted by adjustment of the weighting coefficients of said adaptive channel-equalization and echo-cancellation filtering in response to said extended cepstrum.

A receiver for broadcast digital television signals that periodically include a repetitive pseudo-random noise sequence, said receiver comprising:

• front-end circuitry for supplying an amplified intermediate-frequency signal responsive to a radio-frequency broadcast digital television signal selected for reception;
• demodulator and analog-to-digital conversion circuitry for recovering a digitized baseband broadcast digital television signal from said amplified intermediate-frequency signal, said demodulator and analog-to-digital conversion circuitry connected for receiving said amplified intermediate-frequency signal from said front-end circuitry;
• gating circuitry for selectively reproducing a respective set of successive digital samples descriptive of a selected cycle of each occurrence of said repetitive pseudo-random noise sequence in the digitized baseband broadcast digital television signal recovered by said demodulator and analog-to-digital conversion circuitry;
• DFT computer apparatus for computing the discrete Fourier transform of the power spectrum of said respective set of successive digital samples that said gating circuitry selectively reproduces;
• circuitry for generating a discrete Fourier transform characterizing the actual transmission channel by determining the quotient of
• each term of said discrete Fourier transform of the power spectrum of said respective set of successive digital samples that said gating circuitry selectively reproduces, and
• the corresponding term of a discrete Fourier transform indicative of the response of an ideal transmission channel to the selected cycle of said repetitive pseudo-random noise sequence;
• inverse-discrete-Fourier-transform circuitry for computing the inverse-Fourier transform of said discrete Fourier transform characterizing said actual transmission channel;
• a direct-component-suppression filter connected to receive as its input signal said digitized baseband broadcast digital television signal from said demodulator and analog-to-digital conversion circuitry, said direct-component-suppression filter connected to supply a response to said digitized baseband broadcast digital television signal that suppresses any direct component thereof;
• auto-correlation filtering apparatus of non-cyclical type, connected for performing a linear convolution of a single cycle of a reference pseudo-random noise sequence with each occurrence of said repetitive pseudo-random noise sequence in said response of said direct-component-suppression filter, thereby to generate a correlation result;
• a comb filter connected to receive as its input signal said correlation result and to supply a comb filter response which differentially combines said correlation result with itself as delayed by the duration of one cycle of said repetitive pseudo-random noise sequence, said comb filter response including extended cepstrums characterizing the transmission channel to said receiver for digital television signals, one of said extended cepstrums being generated responsive to the consecutive cycles of said repetitive pseudo-random noise sequence in each data field;
• an extended-cepstrum register connected for selecting from said comb filter response the extended cepstrum generated responsive to the consecutive cycles of said repetitive pseudo-random noise sequence in each data field, to be temporarily stored in said extended-cepstrum register;
• a computer in which a cyclic repetition of the inverse-Fourier transform of said discrete Fourier transform characterizing said actual transmission channel is generated and is pruned in accordance with the extended cepstrum temporarily stored in said extended-cepstrum register to generate a channel impulse response without wrap-around;
• and
• adaptive channel-equalization and echo-cancellation filtering connected for responding to said digitized baseband broadcast digital television signal with a response that is adapted by adjustment of the weighting coefficients of said adaptive channel-equalization and echo-cancellation filtering in response to said channel impulse response without wrap-around.

A receiver for broadcast digital television signals that periodically include a repetitive pseudo-random noise sequence, said receiver comprising:

• front-end circuitry for supplying an amplified intermediate-frequency signal responsive to a radio-frequency broadcast digital television signal selected for reception;
• demodulator and analog-to-digital conversion circuitry for recovering a digitized baseband broadcast digital television signal from said amplified intermediate-frequency signal, said demodulator and analog-to-digital conversion circuitry connected for receiving said amplified intermediate-frequency signal from said front-end circuitry;
• auto-correlation filtering apparatus of cyclical type, connected for performing a circular convolution of a single cycle of a reference pseudo-random noise sequence with a single cycle of pseudo-random noise sequence selected from each occurrence of said repetitive pseudo-random noise sequence in said digitized baseband broadcast digital television signal from said demodulator and analog-to-digital conversion circuitry, thereby to generate a cepstrum characterizing the transmission channel to said receiver for digital television signals;
• and
• a direct-component-suppression filter connected to receive as its input signal said digitized baseband broadcast digital television signal from said demodulator and analog-to-digital conversion circuitry, said direct-component-suppression filter connected to supply a response to said digitized baseband broadcast digital television signal that suppresses any direct component thereof;
• auto-correlation filtering apparatus of non-cyclical type, connected for performing a linear convolution of a single cycle of a reference pseudo-random noise sequence with each occurrence of said repetitive pseudo-random noise sequence in said response of said direct-component-suppression filter, thereby to generate a correlation result;
• a comb filter connected to receive as its input signal said correlation result and to supply a comb filter response which differentially combines said said correlation result with itself as delayed by the duration of one cycle of said repetitive pseudo-random noise sequence, said comb filter response including extended cepstrums characterizing the transmission channel to said receiver for digital television signals, one of said extended cepstrums being generated responsive to the consecutive cycles of said repetitive pseudo-random noise sequence in each data field;
• an extended-cepstrum register connected for selecting from said comb filter response the extended cepstrum generated responsive to the consecutive cycles of said repetitive sequence in each data field, to be temporarily stored in said extended-cepstrum register;
• a computer in which a cyclic repetition is generated of the cepstrum generated by said match filtering apparatus of cyclical type and is pruned in accordance with the extended cepstrum temporarily stored in said extended-cepstrum register to generate a channel impulse response without wrap-around;
• and
• adaptive channel-equalization and echo-cancellation filtering connected for responding to said digitized baseband broadcast digital television signal with a response that is adapted by adjustment of the weighting coefficients of said adaptive channel-equalization and echo-cancellation filtering in response to said channel impulse response without wrap-around.