Patent application number | Description | Published |
20090003459 | 8VSB DTV signals with PCCC and subsequent trellis coding - 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. | 01-01-2009 |
20090016432 | Systems for reducing adverse effects of deep fades in DTV signals designed for mobile reception - 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. | 01-15-2009 |
20090052544 | Staggercasting of DTV signals that employ concatenated convolutional coding - 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. | 02-26-2009 |
20090262799 | TRANSMITTING ADDITIONAL INFORMATION IN THE HEADERS OF ENCAPSULATING DATA PACKETS IN MOBILE/HANDHELD (M/H) DTV SIGNALS - 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. | 10-22-2009 |
20090265751 | Reception of ancillary 8VSB signals controlled responsive to information signaling version of broadcast standard being used - 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. A receiver designed to respond to these modifications to the system of broadcasting is much less likely to malfunction owing to the ESG signal containing error when transmitted or accruing error owing to corruption during transmission. | 10-22-2009 |
20090322961 | System for digital television broadcasting using modified 2/3 trellis coding - Serially concatenated convolutional coding (SCCC) transmitting ancillary data within DTV signals incorporates the ⅔ 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. Soft decisions concerning extrinsic information to be fed back to the ⅔ trellis decoder to close a turbo decoding loop are derived from soft decisions as to the ancillary data, and this derivation includes recoding for a binary-code mapping of symbols to modulation levels. | 12-31-2009 |
20090323823 | SYSTEM FOR DIGITAL TELEVISION BROADCASTING USING MODIFIED 2/3 TRELLIS CODING - 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 ⅔ 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. | 12-31-2009 |
20100037120 | M/H FRAME ENCODING AND DECODING TECHNIQUES FOR 8VSB DTV BROADCASTING SYSTEMS - 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. | 02-11-2010 |
20100061465 | SUB-CHANNEL ACQUISITION IN A DIGITAL TELEVISION RECEIVER DESIGNED TO RECEIVE MOBILE/HANDHELD SIGNALS - When a change in sub-channel selection is made after a mobile/handheld (M/H) Frame is begun, an M/H receiver is for some time unable to correct byte errors by transverse Reed-Solomon (TRS) decoding of turbo decoding results. Despite this, later stages of the M/H receiver are supplied data that cyclic-redundancy-check (CRC) decoding of Internet protocol (IP) packets does not find to be in error. Some of the IP packets comprise Service Map Table (SMT)-mobile/handheld (MH) data used to update SMT determining how the M/H receiver is operated. SMT-MH data that have not been subjected to TRS byte-error correction are kept from updating the SMT until those SMT-MH data are verified by later SMT-MH data subjected to TRS byte-error correction. Transmitting total number of Groups (TNOG)—one information for the currently received M/H Frame in all its sub-frames speeds up acquisition of Fast Information Channel updates by the M/H receiver. | 03-11-2010 |
20100100793 | DIGITAL TELEVISION SYSTEMS EMPLOYING CONCATENATED CONVOLUTIONAL CODED DATA - In iterative-diversity (ID) transmission systems for signals with concatenated convolutional coding (CCC), paired iterative diversity signals each have ½ the code rate of the 8VSB DTV signals prescribed by the 1995 ATSC Digital Television Broadcast Standard. Known serial concatenated convolutional coding (SCCC) or novel parallel concatenated convolutional coding (PCCC) is used in such system. Pairs of CCC signals code data bits and ones' complemented data bits respectively, using similar coding algorithms. Receivers for this transmission system use respective turbo decoders for turbo decoding the earlier-transmitted and later-transmitted CCC signals. Turbo decoding of the earlier-transmitted portions of iterative diversity signals is delayed to be contemporaneous with turbo decoding of the later-transmitted portions of iterative diversity signals. This facilitates the turbo decoders exchanging information concerning confidence levels of data bits during the turbo decoding procedures. | 04-22-2010 |
20100118208 | TIME-DEPENDENT TRELLIS CODING FOR MORE ROBUST DIGITAL TELEVISION SIGNALS - Different sets 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. | 05-13-2010 |
20100124287 | TRANSMISSIONS WITH REDUCED CODE RATE IN 8VSB DIGITAL TELEVISION - 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. The other of the two restricted alphabets of symbols used in PCPM consists of −7, −5, +1 and +3 normalized modulation levels superposed on a background modulation level. | 05-20-2010 |
20100149427 | APPARATUS FOR ADAPTING RECEPTION MODES OF A MOBILE DTV RECEIVER IN RESPONSE TO SIGNALING - Implementation of Fast Information Channel (FIC) signaling when Chunks of FIC information span more than one sub-Frame of an M/H Frame is described. FIC signaling is advanced further at the digital television (DTV) transmitters than originally proposed, thereby eliminating need for substantial amounts of delay memory for coded M/H data in receivers for such data. Each FIC-Chunk includes a bit indicating when it is not applicable only to M/H Frames yet to be received but is also applicable to an M/H Frame being currently received. This facilitates reception being more quickly established after a change in DTV channel selection. Transmission Parameter Channel (TPC) signaling pertaining to the M/H Frame being currently received continues to the conclusion of the M/H Frame, so the total number of M/H Groups in each M/H sub-Frame is signaled to facilitate de-interleaving of the FIC signaling. Code combining of FIC Chunks is described. | 06-17-2010 |
20100225825 | Terminated concatenated convolutional coding of M/H group data in 8VSB digital television signals - M/H Groups each begin with a respective trellis-initialization of ⅔ trellis coding used as inner convolutional coding of concatenated convolutional coding (CCC). Concluding each M/H Group with another trellis-initialization of ⅔ trellis coding terminates the inner convolutional coding of the CCC properly, facilitating bi-directional decoding thereof. Properly terminating the inner convolutional coding of the CCC also facilitates wrap-around turbo decoding of that M/H Group beginning after the earlier training sequence with known 8VSB symbols and concluding with the trellis-initialization of ⅔ trellis coding before that earlier training sequence. At least one further trellis-initialization of ⅔ trellis coding can be inserted into an M/H Group for splitting it into first and second portions that can be decoded separately and that can be efficiently packed by portions of RS Frames employing transverse Reed-Solomon codes of a standard length. | 09-09-2010 |
20100293433 | Burst-error correction methods and apparatuses for wireless digital communications systems - Frames of data that have transverse Reed-Solomon (TRS) coding and subsequent cyclical-redundancy-check (CRC) coding are subjected to de-interleaving before concatenated convolutional coding (CCC). The de-interleaving is related to the symbol interleaving of the outer convolutional coding prior to the inner convolutional coding so as to result in implied interleaving of data bits in the CCC on which wireless digital transmissions are based. The CCC is turbo decoded in a receiver for the wireless digital transmissions and re-interleaved to reproduce soft data, hard data bits of which data are TRS coded. CRC coding is decoded during the turbo decoding procedures and used to influence the confidence levels of the soft data. The confidence levels of the soft data are used for locating byte errors when the TRS coded hard data bits of the soft data are decoded. | 11-18-2010 |
20110037903 | Terminated concatenated convolutional coding of M/H group data in 8VSB digital television signals - M/H Groups each begin with a respective trellis-initialization of 2/3 trellis coding used as inner convolutional coding of concatenated convolutional coding (CCC). Concluding each M/H Group with another trellis-initialization of 2/3 trellis coding terminates the inner convolutional coding of the CCC properly, facilitating bi-directional decoding thereof. Properly terminating the inner convolutional coding of the CCC also facilitates wrap-around turbo decoding of that M/H Group beginning after the earlier training sequence with known 8VSB symbols and concluding with the trellis-initialization of 2/3 trellis coding before that earlier training sequence. At least one further trellis-initialization of 2/3 trellis coding can be inserted into an M/H Group for splitting it into first and second portions that can be decoded separately and that can be efficiently packed by portions of RS Frames employing transverse Reed-Solomon codes of a standard length. | 02-17-2011 |
20110113301 | Diversity broadcasting of gray-labeled CCC data using 8-VSB AM - Receivers for diversity reception of data transmitted by concatenated convolutional code (CCC) from at least one 8-VSB transmitter are described. Each receiver includes a first turbo decoder for the CCC as finally transmitted, a second turbo decoder for the CCC as initially transmitted, and an information-exchange unit connected for exchanging decoding information between the turbo decoders, which perform decoding concurrently. The turbo decoders are designed for decoding CCC formed from an outer convolutional code encoding de-interleaved Gray-coded data and a subsequent binary-coded inner convolutional code forming a 12-phase trellis code in accordance with a Gray-labeling procedure, the outer convolutional code encoding being symbol-interleaved before encoding within said inner convolutional code so said inner convolutional code has implied symbol interleaving in which the original order of data bits is preserved. | 05-12-2011 |
20110135039 | Coding and decoding of 8-VSB digital television signals for mobile/handheld receivers - Modified systems for broadcasting M/H data employ two-dimensional coding of RS Frames that combines transverse RS coding with subsequent byte-error-locating block coding that generates codewords of a prescribed standard length. This prescribed standard length is chosen such that an integral number of codewords of the byte-error-locating block code fits exactly, or substantially so, into the portion of each RS Frame that is encoded in CCC for inclusion within an M/H Group. The byte-error-locating block coding is CRC coding by way of one specific example or is Reed-Solomon (LRS) forward-error-correction (FEC) coding by way of another specific example. M/H receivers are described in which codewords of this byte-error-locating block coding are decoded and used to influence the soft decisions concerning data bits. Then, these soft decisions are processed and used for locating byte errors for the transverse Reed-Solomon (TRS) codes on an individual basis. | 06-09-2011 |
20110138247 | Frequency-diversity 8-VSB am broadcasting to mobile/handheld receivers - A system for broadcasting the same data in concatenated convolutional coded (CCC) form from a network of 8-VSB amplitude-modulation transmitters operated with different radio-frequency carrier waves assigns the coded data to time-interleaved ones of time slots that are universal throughout the network. Therefore, a mobile/handheld (M/H) receiver with a single frequency-agile tuner can provide frequency-diversity reception of the time-interleaved data in CCC form. Alternatively, an M/H receiver with two tuners is used to provide frequency-diversity reception of the time-interleaved data in CCC form. The system for a network of 8-VSB AM transmitters that broadcast the same data in CCC form can further provide for each 8-VSB AM transmitter to make repeated transmissions of data in CCC form, to facilitate iterative-diversity reception of those transmissions by M/H receivers. | 06-09-2011 |
20110164174 | Methods and apparatuses for implementing selective interference-filter pre-coding of main-service 8-VSB DTV Signals - Methods for discontinuing interference-filter pre-coding of 8-VSB digital television (DTV) signals during ancillary-service transmissions are disclosed that do not disrupt reception of main-service DTV signals by receivers already in use. Receivers are disclosed for receiving ancillary-service transmissions without interference-filter pre-coding, which receivers include adaptive channel-equalization filters and subsequent decoders for CCC. The subsequent decoders for CCC respond to data slicing of adaptive channel-equalization filter responses that avoid the reduction of signal-to-noise ratio (SNR) caused by post-comb filtering. Certain of these M/H receivers employ selective post-comb-filtering to flatten the frequency spectrum of main-service components of received 8-VSB DTV signals, while leaving the frequency spectrum of M/H-service components of received 8-VSB DTV signals as received. This is done to generate signal from which filter coefficients for the channel-equalization filters are determined. Certain of these M/H receivers employ decision-feedback equalization (DFE) techniques, which techniques are unaffected by selective interference-filter pre-coding. | 07-07-2011 |
20110222609 | 8VSB DTV signals with PCCC and subsequent trellis coding - Data to be more robustly transmitted within 8VSB broadcast DTV signals are turbo coded using parallel 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. | 09-15-2011 |
20110235723 | Utilization of (207, 187) Reed-Solomon coding in mobile/hand-held digital television receivers - Receivers for recovering ancillary data from parallel concatenated convolutional coding. (PCCC) imbedded in digital television (DTV) signals can utilize the non-systematic (207, 187) Reed-Solomon (RS) codewords included in the DTV signals to facilitate DTV receivers already in the field to continue being able to receive main-service transmissions. Such a receiver attempts to decode each non-systematic (207, 187) RS codeword in a time slot selected for reception. If such RS decoding is successful, indication of such success is used to verify the correctness of bits of the ancillary data or correct them when turbo decoding the PCCC encoding ancillary data in the time slot selected for reception. The updating of ancillary data bits during cycles of turbo decoding updates the non-systematic (207, 187) RS codewords in the time slot selected for reception, increasing the likelihood of RS decoding of those RS codewords being successful during subsequent cycles of turbo decoding. If all the non-systematic (207, 187) RS codewords in the time slot selected for reception are successfully decoded before reaching a prescribed maximum number of cycles of turbo decoding, turbo decoding can be discontinued early to conserve operating power. | 09-29-2011 |
20120204080 | Utilization of non-systematic (207, 187) Reed-Solomon coding in mobile/hand-held digital television receivers - Non-systematic (207, 187) Reed-Solomon codewords contain valuable information concerning the correctness of the outer convolutional coding of the serial concatenated convolutional coding, (SCCC) used for transmitting M/H-service data. An M/H receiver can decode the non-systematic (207, 187) Reed-Solomon coded MHE packets before and during turbo decoding of the SCCC. The decoding results are used to influence the soft decisions concerning bits of the SCCC that arise during SCCC decoding procedures. The decoding results can sometimes correct errors in the outer convolutional coding of the SCCC. The decoding results can be employed to stop the iterative SCCC decoding procedures sometimes before reaching a prescribed maximum number of iterations. | 08-09-2012 |
20120268659 | Slot-interleaved decoding of concatenated convolutional coding in mobile/hand-held digital television receivers - At least two turbo decoding apparatuses are used in a receiver for concatenated convolutional coding transmissions imbedded in 8-VSB digital television signals. This permits turbo decoding procedures for the M/H Groups in any Parade consisting of eight or fewer M/H Groups to be interleaved so at least one M/H Slot interval after each of those M/H Groups has been received is available for decoding that M/H Group. | 10-25-2012 |
20130002962 | Systems for reducing adverse effects of deep fades in DTV signals designed for mobile reception - 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. | 01-03-2013 |
20130028269 | DTV systems employing parallel concatenated coding in COFDM transmissions for iterative diversity reception - A digital television (DTV) system uses parallel concatenated coding (PCC), together with QAM constellations for modulating OFDM carriers. A first encoder responds to bits of randomized data to generate a first component of parallel concatenated coding. A second encoder responds to delayed bits of the randomized data to generate a second component of parallel concatenated coding. A constellation mapper generates QAM symbols responsive to successive time-slices of the first component of the PCC interleaved with successive time-slices of the second component of the PCC. An OFDM modulator generates a COFDM modulating signal responsive to the QAM symbols. In a receiver for the DTV system, the second component of the PCC and delayed first component of the PCC are iteratively decoded. Corresponding soft bits from the second component and delayed first component of the PCC are combined to supply soft randomized data used in that iterative decoding. | 01-31-2013 |
20130028271 | COFDM digital television receivers for iterative-diversity reception - Receivers with capability for iterative-diversity reception of COFDM digital television transmissions of repeated similarly coded data are described. Also described are receivers with capabilities for receiving COFDM digital television transmissions in which earlier transmissions of coded data are later followed by subsequent transmissions of the same data differently coded. The receivers use maximal-ratio code combining techniques for repeated components in the COFDM digital television transmissions. The receivers use turbo decoding techniques for concatenated coding of data in the COFDM digital television transmissions. | 01-31-2013 |
20130028335 | Digital broadcasting systems using parallel concatenated coding of bit-complementary bitstreams - A digital television (DTV) system uses parallel concatenated coding (PCC), together with QAM constellations for modulating OFDM carriers. A first encoder responds to ONEs' complemented bits of randomized data to generate a first component of PCC. A second encoder responds to delayed bits of the randomized data to generate a second component of PCC. A constellation mapper generates QAM symbols responsive to successive time-slices of the first component of the PCC interleaved with successive time-slices of the second component of the PCC. An OFDM modulator generates a COFDM modulating signal responsive to the QAM symbols. In a receiver for the DTV system, the second component of the PCC and delayed first component of the PCC are iteratively decoded. Soft bits from the second component and delayed first component of the parallel concatenated coding are code-combined to supply soft randomized data used in that iterative decoding. | 01-31-2013 |
20130028336 | Receivers for COFDM digital television transmissions - A receiver of COFDM digital television signals includes an inner decoder for iterative soft-decision decoding of concatenated convolutional coding (CCC) and an outer decoder for Reed-Solomon (RS) coding. The receiver generates error flags for identifying code symbols to be erased before the output symbols from the inner decoder are byte de-interleaved and supplied to the outer decoder. Generation of those flags depends on soft decoding results from the inner decoder. The method of locating errors ascribes to each byte supplied to the outer decoder for RS coding the highest lack-of-confidence level specified by the soft data bits associated with that byte. The method is described as being extended to locate byte errors in plural-dimension cross-interleaved Reed-Solomon codes (CIRC) apt to be employed in DTV broadcasting to mobile and handheld receivers. | 01-31-2013 |
20140119458 | COFDM broadcast systems employing turbo coding - Turbo-coded data are transmitted using quadrature amplitude modulation (QAM) of COFDM carrier waves in digital television (DTV) broadcast systems. The QAM symbol constellations map the parity bits of the turbo coded data so as to be de-mapped with higher confidence levels than the data bits, facilitating turbo decoding. A preferred DTV receiver delays the first transmissions of time-slices of a service selected for iterative-diversity reception to concur with second transmissions of those time-slices. The complex coordinates of QAM constellations in the delayed first transmission and the second transmission of the same time-slice are combined by a maximal-ratio QAM combiner after COFDM demodulation, but before de-mapping QAM constellations and turbo decoding. In a less-preferred DTV receiver, QAM constellations in the delayed first transmission of each time-slice and in the second transmission of the same time-slice are de-mapped separately. A maximal-ratio code combiner then combines de-mapping results before turbo decoding. | 05-01-2014 |
20140161209 | COFDM broadcasting with single-time retransmission of COFDM symbols - Transmitter apparatus to broadcast coded orthogonal frequency-division multiplexed (COFDM) radio-frequency carriers conveying digital television (DTV) signals encoded using Bose-Chaudhuri-Hocquenghem (BCH) coding concatenated with subsequent low-density parity-check coding (LPDC) transmits the same coded DTV signals twice some time apart. The coded DTV signals are mapped to quadrature amplitude modulation (QAM) of the COFDM carriers. Preferably, the circular Fourier transforms of COFDM symbols in the earlier transmissions are rotated one half revolution respective to the circular Fourier transforms of corresponding COFDM symbols in the later transmissions. Receiver apparatus combines the earlier and later transmissions of twice-transmitted COFDM signals as part of iterative procedures for de-mapping QAM and decoding the concatenated BCH-LDPC coding of the DTV signals. | 06-12-2014 |
20140177731 | Remedying low densities of ONEs in transmission and reception of digital television signals - In a DTV transmitter the bits of shortened BCH codewords that exhibit undesirably low densities of ONEs are ONEs' complemented before being further coded, and used to modulate carrier waves. In a DTV receiver the further coding is decoded after demodulation. The results of such decoding are processed to recover successive shortened BCH codewords, some of which are in TRUE form and others of which have had their bits ONEs' complemented. Each shortened BCH codeword is extended to full length with ZEROs, and decoding is attempted. Successful decoding confirms that the shortened BCH codeword was received in TRUE form. If decoding is unsuccessful, the bits of the shortened BCH codeword as received are ONEs' complemented, extended to full length with ZEROs, and decoding is attempted. Successful decoding confirms that the shortened BCH codeword was received in ONEs' complemented form and has subsequently been converted to TRUE form. | 06-26-2014 |