Abstract: Procedures performed prior to convolutional interleaving of 8VSB digital television signals restrict the alphabet of symbols in novel methods of generating trellis-coded digital television signals that include more robust symbol coding using a restricted alphabet of symbols selected from a full 8VSB symbol alphabet consisting of ?7, ?5, ?3, ?1, +1, +3, +5 and +7 normalized modulation levels superposed on a background modulation level. Certain of these novel procedures generate pseudo-2VSB or P-2VSB robust symbol coding with a restricted alphabet of symbols consisting of ?7, ?5, +5 and +7 normalized modulation levels superposed on a background modulation level. Others of these novel procedures generate prescribed-coset-pattern-modulation or PCPM robust symbol coding intermixing two restricted alphabets of symbols according to a prescribed pattern. One of the two restricted alphabets of symbols used in PCPM consists of ?3, ?1, +5 and +7 normalized modulation levels superposed on a background modulation level.

Abstract: Different sets of symbols are precluded at prescribed times in time-dependent trellis coding. This increases the distances between different individual symbols as well as the distances between trellis codes, which increases the robustness of data transmission. The symbols that are precluded in this time-dependent trellis coding are determined in advance according to a prescribed pattern, which pattern does not depend on the history of previous symbols. The Viterbi decoder used for trellis decoding in a receiver can be designed to take advantage of knowledge concerning which different sets of symbols are precluded at prescribed times.

Abstract: Modification of the prior-art M/H system to better suit transmission of internet-protocol (IP) transport packets includes a standard codeword length for a plurality of various options for transverse Reed-Solomon coding of M/H data, which options offer different degrees of forward-error-correction capability. A 235-byte standard codeword length for TRS coding of M/H data allows extending the FIC-Chunks in the Fast Information Channel signaling to double length so as to substantially increase the capability of such signaling to convey information concerning M/H services. In some transmitter apparatus constructed in accordance with aspect of the invention the TRS encoder in the M/H Frame encoder is modified for transmitting the parity bytes of TRS codewords before, rather than after, the data bytes of those TRS codewords.

Abstract: The outer convolutional coding of the signals used to transmit mobile-handheld (M/H) service data within digital-television (DTV) signals is subjected to anti-Gray coding, either before or after its interleaving, but before its inner convolutional coding. In a receiver for such M/H-service data, portions of the trellis decoded DTV signal containing soft decisions concerning symbol-interleaved convolutionally coded M/H-service data are recoded for a Gray-code mapping of symbols to modulation levels. This is done either before or after symbol de-interleaving, but before decoding the outer convolutional coding. Soft decisions concerning extrinsic information to be fed back to the ? trellis decoder to close a turbo decoding loop are derived from soft decisions as to the M/H-service data, which derivation includes re-coding for a binary-code mapping of symbols to modulation levels. Each re-coding procedure can be performed using ROM, but preferably is performed using simple digital logic.

Abstract: Serially concatenated convolutional coding (SCCC) transmitting ancillary data within DTV signals incorporates the ? trellis coding used for all DTV signals as its inner convolutional coding. The outer convolutional coding of the SCCC is subjected to _“anti-Gray”_ coding, either before or after its interleaving, but before its inner convolutional coding. In a receiver for ancillary data as so transmitted, simple logic circuitry recodes portions of the trellis decoded DTV signal containing soft decisions as to the symbol-interleaved convolutionally coded ancillary data to provide a Gray-code mapping of symbols to modulation levels. This recoding is done either before or after symbol de-interleaving, but before decoding the outer convolutional coding to recover ancillary data.

Abstract: Modifications to the system of broadcasting robustly coded ancillary transmissions to mobile and portable receivers of 8VSB digital television signals include version information as part of signal transmissions besides those made specifically to support an electronic service guide (ESG). This version information indicates what version of broadcast standard the signals complied with when transmitted. Such modifications allow such a receiver to determine whether it has the capability to process received ancillary transmissions usefully, without the receiver having to refer to an ESG derived from robustly coded ancillary transmissions that have been fully decoded. Such determination allows the receiver to avoid decoding of the robustly coded ancillary transmissions or to curtail such decoding after partial completion thereof, which reductions in decoding procedures reduce battery drain in battery-powered mobile and portable receivers.

Abstract: Apparatus for transmitting digital data in an 8-vestigial sideband (8-VSB) signal format for reception by mobile/handheld (M/H) receivers is described. The apparatus for transmitting digital data includes a generator of MHE packet headers that include additional information about at least part of the digital data and a packet formatter that installs the MHE packet headers in the MHE packets. Apparatus for receiving the digital data and recovering the additional information from the MHE packet headers to be used for modifying operation of the receiving apparatus is also described.

Abstract: 8VSB digital television signals employing serially concatenated convolutional coding (SCCC) are transmitted twice in an SCCC staggercasting procedure. In the receiver for such signal “soft” decisions concerning the initial and final transmissions are compared as a basis for synthesizing a set of “soft” decisions for implementing turbo decoding procedures. In a “punctured” variant of the SCCC staggercasting procedure, SCCC using one type of outer convolutional coding is transmitted at a relatively early time and after a prescribed interval SCCC using another type of outer convolutional coding of the same data is transmitted at a relatively late time. In the receiver for such signal “soft” decisions concerning data bits the initial and final transmissions are compared as a basis for synthesizing a set of “soft” decisions for implementing turbo decoding procedures.

Abstract: Synchrodyning apparatus in which a PAM IF signal is mixed with unmodulated carriers nominally at the frequency of the carrier, which unmodulated carriers are in quadrature with respect to each other. E.g., the PAM IF signal may be an intermediate-frequency 8VSB digital television signal. The baseband signals resulting from the mixing procedures are additively combined and differentially combined to generate real and imaginary components of a complex baseband signal. The real component of the complex baseband signal is processed for reproducing the digital signal used to modulate the transmitted RF carrier. An automatic frequency and phase control (AFPC) signal for controlling the oscillator circuitry generating the unmodulated carriers is generated by an AFPC detector responding to the imaginary component of the complex baseband signal or to both components of the complex baseband signal.

Abstract: Digital television broadcasting signals employ parallel concatenated convolutional coding, commonly called “turbo coding”, to improve reception by receivers in motor vehicles. Turbo coded Reed-Solomon codewords are transversally disposed in the payload fields of encapsulating MPEG-2-compliant packets to improve the capability of the Reed-Solomon coding to overcome deep fades. Turbo codewords are transmitted more than once in so-called “staggercasting”. Reception of DTV signals is improved by combining soft decisions concerning repeated transmissions of turbo codewords before turbo decoding. Only the data components of turbo codewords are transmitted twice in “punctured” staggercasting of turbo codewords, with parity components being transmitted only once, so code rate is reduced by a smaller factor than two.

Abstract: Data to be more robustly transmitted within 8VSB broadcast DTV signals are turbo coded using parallelly concatenated convolutional coding (PCCC) and incorporated within the segments of data fields, the bytes of which are convolutionally interleaved before trellis coding and 8VSB symbol mapping. Packing the PCCC into payload fields of MPEG-2-compatible null data packets and Reed-Solomon coding the packets to generate the segments of data fields, the bytes of which are convolutionally interleaved, conditions legacy DTV receivers to disregard PCCC components not useful to them. Transversal packing turbo-coded Reed-Solomon codewords into the payload fields of MPEG-2-compatible null data packets increases the capability of those turbo-coded Reed-Solomon codewords to overcome burst errors. Repeated transmissions of the transversally packed turbo-coded Reed-Solomon codewords in whole or in part allows them to overcome protracted deep fades encountered during mobile reception of 8VSB DTV signals.

Abstract: An echo cancellation reference signal is generated within a DTV transmitter by approximating a pair of successive repetitive PN sequences with 8VSB symbols arranged in sequences that are capable of being generated by ? trellis coding. The trellis coding is controlled so that the two sequences of 8VSB symbols can be linearly combined to generate a repetitive PN sequence doubled in amplitude and superposed on a constant-value pedestal. After this linear combining is performed by a comb filter in a DTV receiver, the resulting signal is convolved with the PN sequence as known a priori at the DTV receiver. This is a correlation procedure which generates the impulse response of the channel through which the DTV signal was received. The channel impulse response (CIR) provides a basis for computing the weighting coefficients of adaptive channel-equalization filtering in the DTV receiver.

Abstract: Redundant coding of 8VSB digital television signals using (12, 8) linear block codes reduces code rate by a third. The parity bits for the (12, 8) block coding of the bytes in a pair of (207, 187) Reed-Solomon codewords are transmitted in a 207-byte segment of data. The information bits contained in each pair of (207, 187) Reed-Solomon codewords are subsequently transmitted in 207-byte segments of data that can be usefully received by legacy digital television receivers. A preferred (12, 8) linear block coding is the equivalent of Gray coding followed by rearranged shortened (15, 11) Hamming coding followed by Gray decoding. Digital television transmitter apparatus capable of generating such redundantly coded signal is described. So is digital television receiver apparatus capable of receiving and decoding such redundantly coded signal to secure more robust reception.

Abstract: Electromagnetic signals for transmitting television and other information more robustly have amplitudes modulated in accordance with a digital signal generated by convolutional interleaving and trellis coding of segments of successive data fields, each of which segments contains a prescribed number of bytes. In improvements of these signals, respective fractional portions of a Reed-Solomon forward-error-correction codeword are transmitted in respective ones of a plurality of the segments of the successive data fields. The respective ones of the plurality of segments are separated from each other within the successive data fields, such that their individual bytes do not interleave with each other after the convolutional interleaving and trellis coding are completed.

Abstract: A data field of transmitted digital television signals includes a first set of A/53-compliant data segments that convey payload information and further includes a second set of A/53-compliant data segments that contain parity bytes for transverse Reed-Solomon forward-error-correction coding of the data contained within the first set of A/53-compliant data segments. A digital television receiver uses the parity bytes in the second set of A/53-compliant data segments to implement transverse Reed-Solomon forward-error-correction decoding that corrects byte errors in the data contained in the first set of A/53-compliant data segments.

Abstract: An adjustable K-factor-improvement (KFI) filter having a sparse kernel composed of non-zero weighting coefficients of substantially equal amplitudes is included in a receiver for digital television signals or the like. The receiver includes apparatus for measuring the channel impulse response (CIR) or cepstrum of the signal as received. The respective polarities of the non-zero weighting coefficients in the sparse kernel of the adjustable KFI filter are adjusted responsive to the measured CIR. The differential delay between each successive pair of non-zero weighting coefficients in the sparse kernel of the adjustable K-factor-improvement filter is adjusted responsive to the measured CIR. The adjustment is such that the KFI filter response has a principal component with substantially more energy than any of its echo components. The KFI filter response is applied as input signal to subsequent adaptive equalization filtering in the receiver.

Abstract: A vestigial-sideband (VSB) signal is converted to a double-sideband amplitude-modulation signal having information that is subsequently detected in the double-sideband amplitude-modulation signal. A method for performing the conversion includes mixing the VSB signal with a first beat frequency different from a carrier frequency of the VSB signal, the first beat frequency being of such value as to generate a first mixing result that is translated in frequency to have a carrier at an offset frequency; mixing the VSB signal with a second beat frequency different from the carrier frequency of the VSB signal and from the first beat frequency, the second beat frequency being of such value as to generate a second mixing result that is translated in frequency to have a earner at the offset frequency; and combining the first and second mixing results to form the double-sideband amplitude-modulation signal with a carrier frequency at the offset frequency.

Abstract: A data field of transmitted digital television signals includes a first set of A/53-compliant data segments that convey payload information and further includes a second set of A/53-compliant data segments that contain parity bytes for transverse Reed-Solomon forward-error-correction coding of the data contained within the first set of A/53-compliant data segments. A digital television receiver uses the parity bytes in the second set of A/53-compliant data segments to implement transverse Reed-Solomon forward-error-correction decoding that corrects byte errors in the data contained in the first set of A/53-compliant data segments.

Abstract: A radio receiver for receiving a selected digital HDTV signal, irrespective of whether it is a complex-amplitude-modulation (QAM) or a vestigial sideband (VSB) signal, using the same tuner. The tuner supplies a final IF signal in a 6 MHz frequency band, the lowest frequency of which is not appreciably more than 2.38 MHz. The final IF signal is digitized for synchrodyning to baseband, with the 2.375 MHz difference between the carrier frequencies of QAM and VSB signals being taken into account in the digital synchrodyning circuitry. The carrier frequencies of the QAM and VSB final IF signals are regulated to be submultiples of symbol frequency by applying automatic frequency and phase control signals developed in the digital circuitry to a local oscillator of the tuner. The presence of the pilot carrier accompanying a selected VSB HDTV signal is detected for automatically switching the radio receiver for operation in a VSB signal reception mode.

Abstract: A radio receiver for receiving a selected digital TV signal uses final intermediate frequency signals the carrier frequencies of which are multiples of symbol rate. The radio receiver has a match filter receptive of rectified samples of digitized intermediate-frequency signal and responsive to the amplitude of the intermediate-frequency carrier being modulated in accordance with the field synchronization code group to generate a pulsed response to the beginning of each data field. This pulsed response is used to determine when data segment synchronization information should occur, so its detection is more certain to be accurate and data segment synchronization is more rapidly determined. Symbol synchronization is rapidly inferred from the field synchronization and data segment synchronization, so that the samples in each data line can be counted.