Mapping arrangement for digital communication system

Technical Field of the Invention

The present invention relates to the transmission and / or reception of digital data and is a divisional patent application of the application Act N⁵ P 01 01792, filed on 04/07/2001.

Background of the Invention

The norm in the United States of America for the transmission of television digital signals that is known as VSB8 data - vestigial sideband (ATSC Digital Television Standard A / 53 - Advanced Television Systems Committee). This VSB8 data has a constellation consisting of eight possible levels of symbols. In a VSB system, the eight possible levels of symbols are all in the same phase. In a QAM system, (quadrature amplitude modulation), however, the symbols are transmitted in phase quadrature ratio.

The standard referred to above specifies the formatting and modulation of digital video data into audio data. The transmitted data is in the form of symbols, each symbol representing two bits of data that are encoded with networked coding in three bits of data encoded with networked coding. Each three bits of data encoded with network coding are formatted in a symbol that has a corresponding one of

210,439 eight levels. Reed / Solomon coding is also provided in APP / elr.

interspersed to increase the robustness of the transmitted information.

<img file="AR042249A2_D0001.tif" />

digital and audio data) are also transmitted ^ e.nuun -cariai de télévision digital. This data is formatted and modulated according to the standard in the same way as video and audio data. Receivers produced in accordance with VSB 8 can also read packet identifications (PIDs) that allow receivers to differentiate between audio, video, and auxiliary data.

However, while the robustness of the transmitted digital television signals is sufficient for digital television reception, this robustness may not be sufficient for the transmission of auxiliary data, in particular when the auxiliary data is essential. Accordingly, one of the applications of the present invention is the transmission of auxiliary data in a VSB format with external encoding for added robustness. The auxiliary data transmitted in accordance with the application of the present invention is referred to in the present application as robust VSB data (RVSB).

Summary of the Invention

In one aspect of the present invention, a method comprises the following: receiving a digital serial, in which the digital digitai contains robust VSB data, and in which the digital digitai also contains a map that allows a receiver to process data from Robust VBS, in which the robust VSB data contains a duplicate of the map; and process the robust VSB data and the duplicate map in response to the map.

In another aspect of the present invention, an apparatus comprises a receiver, a decoder, and a processor. The receiver receives a digital serial, and the serial digitai contains a table of first data of VSB 8 and second data of VSB 8. The first data of VSB 8 and the second data of VSB 8 have different bit transfer rates. The serial digitai also contains a map, and

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The map contains information that indicates a location of at least one of the first VSB 8 data and the second VSB 8 data in the table. The decoder decodes the digital serial. The processor processes the first VSB 8 data according to the location information contained in the map.

In yet another aspect of the present invention, an electrical serial comprises a map, first data symbols, and second data symbols. The first data symbols and the second data symbols are given in the same constellation, the first data symbols and the second data symbols have different bit rates, in which the first data symbols and the second data symbols data is intermingled in a data box, and the map contains information indicating a location of at least one of the first VSB 8 data and the second VSB 8 data in the electrical serial.

In another aspect of the present invention, an apparatus comprises a receiver, a decoder, and processor. The receiver receives a digital serial, and the serial digitai contains a table of first data of VSB 8 and second data of VSB 8. The first data of VSB 8 and the second data of VSB 8 have the same constellation, and the first data of VSB 8 and the second VSB 8 data have different bit rates. The serial digitai also contains a map, and the map contains information that indicates a location of the first VSB 8 data in the table. The decoder decodes the serial digitai. The processor discards the second VSB data and processes the first VSB 8 data.

In another aspect of the present invention, an apparatus comprises a receiver and a first processor and a second processor. The receiver receives a digital signal, and the serial digitai contains a robust VSB data box, ATSC data, or both. At least, ATSC data has PID numbers

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\ · / '' Ff / FOUQ Z · '.:

ί ¹ &gt; / \· ....../ ,» $

f ./Ε, _,. ** · *** ♦ associated with them. The digital signal contains adëmâs a map, and the map contains information that indicates a robust VSB data location in the box. The first processor processes the robust VSB data based on the map. The second processor processes the ATSC data based on PID numbers.

Brief Description of the Drawings

These and other features and advantages will be given more evidence based on a detailed consideration of the invention in conjunction with the drawings, in which:

Figure 1 shows a robust VSB transmitter for transmitting robust VBS data and ATSC data in accordance with the present invention.

Figure 2 shows a standard ATSC receiver to receive the ATSC data transmitted by the robust VSB transmitter of Figure 1.

Figure 3 shows a robust VSB receiver for receiving the robust VSB data transmitted by the robust VSB transmitter of Figure 1.

Figure 4 shows the 2/3 rate encoder of Figure 1 in additional detail.

Figure 5 shows the mapping function performed by the mapper of Figure 4.

Figure 6 shows the operation of the 2/3 rate decoders of Figures 2 and 3.

Figure 7 shows another robust VSB transmitter for transmitting robust VSB data and ATSC data according to the present invention.

Figure 8 shows a standard ATSC receiver for receiving the ATSC data transmitted by the robust VSB transmitter of Figure 7.

Figure 9 shows a robust VSB receiver for receiving the robust VSB data transmitted by the robust VSB transmitter of Figure 7.

Figure 10 shows a circuit for generating the appropriate control serial in the discard control line of Figure 9.

<img file="AR042249A2_D0005.tif" />

robust VSB data and ATSC data in accordance with the present invention.

Figure 12 shows an example of four data segments containing external 1/2 rate encoded data that can be transmitted by a robust VSB transmitter according to the present invention.

Figure 13 shows an example of four data segments containing external encoded 1/4 rate data that can be transmitted by a robust VSB transmitter according to the present invention.

Figure 14 shows an example of four data segments containing external encoded data of 3/4 rate that can be transmitted by a robust VSB transmitter according to the present invention.

Figure 15 shows the interleavers (l_r) of figures 1,9 and 11 in greater detail.

Figure 16 shows the deintercalers (D_r) of Figures 3 and 9 in greater detail.

Figure 17 shows a map definition structure of a first robust VSB data packet of a frame.

Figure 18 shows a portion of the frame synchronization segment of a frame that carries a map indicating where in the robust VSB data the frame can be found.

Figure 19 illustrates an improved slice predictor according to an embodiment of the present invention.

Figure 20 shows the fabric for the internal decoder of Figure 19.

Figure 21 shows possible state transitions for the external decoder of Figure 19; Y

Figure 22 illustrates an improved slice predictor according to another embodiment of the present invention.

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Detailed description

Transmission and Reception of RVBS and ATSC data

Figure 1 shows a robust VSB transmitter 10 that transmits both ATSC data and robust VSB data in accordance with an embodiment of the present invention. Figure 2 shows a standard ATSC receiver 12 that receives the ATSC data transmitted by the robust VSB transmitter 10, and Figure 3 shows a robust VSB receiver 14 that receives the robust VSB data transmitted by the VSB transmitter 10 robust

The robust VSB transmitter 10 includes a Reed / Solomon encoder 16 that encodes bytes of uncoded auxiliary data by adding bytes of Reed / Solomon parity to the bytes of uncoded auxiliary data. The bytes of uncoded auxiliary data and the Reed / Solomon parity bytes are interleaved by an interleaver 18. Then, the bytes of interleaved uncoded auxiliary data and the Reed / Solomon parity bytes are encoded in terms of bytes by an external encoder 20 using a convolutional code or other error correction code. The external encoder 20 improves the robustness of the uncoded auxiliary data bytes and the Reed / Solomon parity bytes, converting them into robust data bytes (which are referred to below as bytes of robust VSB data) and Reed / Solomon parity bytes.

The external encoder 20, for example, may be a 1/2 rate encoder that produces two output bits for each input bit, and a 1/4 rate encoder that produces four output bits for each input bit, or a 3/4 rate encoder that produces four output bits for every three input bits. I know

-7ΜΓΜΜ 'Μ' POLtn \ &amp; ^ (O^Wt'11 could use other encoders.

At the output of the external encoder 20, a transport header (tx) of three bytes is added to each group of 184 robust encoded VSB data and Reed / Solomon bytes to form robust VSB data packets. A multiplexer 24 multiplies these robust VSB data packets with ATSC data packets (typically, video and audio), each of which comprises a transport header of three bytes and 184 bytes of ATSC data. Any of the inputs to multiplexer 24 can be selected on a package-by-package basis, and each selected input is supplied to an ATSC transmitter 26. The selection by multiplexer 24 on which input passes to ATSC transmitter 26 is based on a robust VSB map to be described below.

ATSC transmitter 26, as is typical, includes a Reed / Solomon encoder 28, an interleaver 30, and an internal encoder 32 of 2/3 rate, all of which operate in accordance with the ATSC standard.

A standard ATSC receiver, such as the standard ATSC receiver 12 shown in Figure 2, receives and processes the ATSC data and discards the robust VSB data. Accordingly, the standard ATSC receiver 12 includes an internal decoder 34 of 2/3 rate, a deinterleaver 36, and a Reed / Solomon decoder 38, all of which operate in accordance with the ATSC standard. However, the standard ATSC receiver 12 is programmed to decode both the ATSC data and the robust VSB data transport headers (which include the packet or PID identifications and that have not been encoded by the external encoder 20). The standard ATSC receiver 12 reads the PIDs of all packets and, at 40, discards the packets that have the PIDs of the robust VSB data. The standard ATSC receiver 12 also includes a slice predictor 42 (such as the slice predictor disclosed in the patent of

<img file="AR042249A2_D0007.tif" />

the United States of America 5,923,711) which has an answer to the internal decoded data and which provides an output back to a follower and / or phase compensator, as is known in the art.

The robust VSB data packets can be received, decoded and processed by a robust VSB receiver such as the robust VSB receiver 14 shown in Figure 3. As is known, and as shown in Figure 4, the Internal 32 encoder rate 2/3 of the ATSC transmitter 26 includes a precoder 44 and a four-state frame encoder 46. In combination, the precoder 44 and the four-state frame encoder 46 can be considered as an eight-state encoder that produces three bits of coded outputs (ZO Z1 Z2) for every two input bits (X1 X2). A mapper 48 maps the three output bits encoded per frame to a symbol that has one of eight levels as shown in Figure 5. As is well known from the theory of convolutional common code, the operation of the precoder 44 and the four-state network encoder 46 can be considered as a quaternary network of eight states.

Therefore, in the robust VSB receiver 14, an internal 2/3 rate decoder 50 may operate in an eight state quaternary framework that considers precoder 44 and four state frame encoder 46 of the internal rate encoder 32 2/3 in combination as shown in Figure 6 to produce a transitional exit decision (using, for example, the SSA algorithm described in the article entitled “Optimal Transitory Output Decision for Channels with Intersymbol Interference”, by Li, Vucetic, and Sato, Proceedings of the IEEE on Information Theory, May 1995). This transitional decision-making operation is more complicated than the widely used Viterbi algorithm, which produces a permanent decision output, but the transitional decision-making operation takes more profit from the gain.

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of coding provided by the external encoder 20.

The output of the internal decoder 50 of 2/3 rate is uninterleaved by a deinterleaver 52. The robust VSB receiver 14 reads the PIDs of all packets at the output of the deinterleaver 52. Based on these PIDs, the robust VSB receiver 14 discards packets in 52 that have the ATSC data PIDs and also discards the transport headers added following the external encoder 20 and the parity bytes added by the Reed / Solomon 28 encoder. Thus, the robust VSB receiver 14, at 54, passes only the robust VSB data packets containing the robust VSB data encoded by the external encoder 20. The robust VSB data packets are decoded with an external decoder 56, uninterleaved by a deinterleaver 58, (which is the inverse of interleaver 18), and decoded in Reed / Solomon by a Reed / Solomon decoder 60 in order to reconstruct the Original uncoded auxiliary data supplied by Reed / Solomon encoder 16 of Figure 1.

The reliable output of the decoder 56 (which can use transient output or permanent output) is interleaved by an interleaver 62 (corresponding to the interleaver 30) in the feedback path 64 in order to restore the ordering of the decoded data external to the order of the data in the channel. This interleaved external decoded data can be used, for example, by a slice predictor 66 to create reliable feedback to a follower and / or phase compensator. However, the total feedback delay introduced by the deinterleaver 52 and the interleaver 62 in the robust VSB receiver 14 is generally too long to provide useful feedback to the phase follower and / or compensator.

The arrangement shown in Figures 7, 8 and 9 avoids the feedback delay introduced by the deinterleaver 52 and the interleaver 62 of the

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robust VSB receiver 14. Figure 7 shows a robust VSB transmitter 80 in which the bytes of uncoded auxiliary data are encoder by a Reed / Solomon encoder 82 that adds bytes of Reed / Solomon parity to the bytes of uncoded auxiliary data. The auxiliary data bytes not coded and the parity bytes of Reed / Solomon are interleaved by an interleaver 84. Then, the bytes of interleaved uncoded auxiliary data and the Reed / Solomon parity bytes are encoded in terms of bits by an external encoder 86 using a convolutional code or a turbo product code, as noted above. The output in what refers to bit of the external encoder 86 is a small block interleaved by a small block interleaver 88 in order to reduce the impact of batch errors in the channel on the external decoding. All the data provided by the small block interleaver 88 can be referenced as data R (no) which means robust VSB data normally ordered.

An input of a first multiplexer 92 receives packets formatted in ATSC, each comprising (i) a three-byte transport header valid with a PID amount for robust VSB data, (ii) 184 bytes of data place conservation Robust VSB dummy, and (iii) twenty bytes occupying a place for dummy ATSC Reed / Solomon parity data. The other input of the first multiplexer 92 receives dummy packets formatted in ATSC, each of which comprises 207 bytes of dummy ATSC data. These dummy packages formatted in ATSC serve as placeholders for actual ATSC packages to be added downstream.

The inputs of the first multiplexer 92 can be selected on a package-by-package basis, and this selection is based on the robust VSB map to be described below.

The selected output of the first multiplexer 92 is interleaved by a

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<img file="AR042249A2_D0011.tif" />

interleaver 94 according to the ATSC Standard for convolutional byte interleaving. A data substituent 96 receives the interleaver output 94 and the interleaver output 88 of small blocks. The data substituent 96 replaces each dummy robust VSB data place preservation byte from interleaver 94 with the next normally ordered robust VSB data byte from interleaver 88 of small blocks.

The data substituent output 96 contains robust VSB data normally ordered with interleaved transport headers, dummy ATSC Reed / Solomon parity bytes, and dummy ATSC data packet bytes. A deinterleaver 98, which operates according to the ATSC standard for byte deinterleaving, deinterleaves the output of the data substituent 96 to thereby effectively "repackage" the data as transport header packets, robust VSB data reordered (R data (ro)), fictitious ATSC Reed / Solomon parity bytes, and fictitious ATSC data. The reordering of the reordered robust VSB data normally results from the deinterleaving of the deinterleaver 98, and the reordered data can be referred to as reordered robust VSB data.

The dummy ATSC Reed / Solomon parity bytes (20 per packet) of the robust VSB packets and the dummy ATSC data packets (207 bytes per packet) are discarded at 100. The remaining robust VSB packets, each of which includes a header and transport and re-ordered robust VSB data, are multiplexed with a multiplexer 102 with actual ATSC data packets, each of which contains 187 bytes of a header of ATSC transport and data. Any of the inputs to the second multiplexer 102 may be selected on a package-by-package basis and is supplied to an ATSC transmitter 104. The selection by the second multiplexer 102 of which input to be passed to the ATSC transmitter 104

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It is based on the robust VSB map to be described below.

The ATSC transmitter 104 typically includes a Reed / Solomon 106 encoder, an interleaver 108, and an internal encoder 110 of 2/3 rate 2/3, all of which operate in accordance with the ATSC standard. Reed / Solomon encoder 106 produces packets of transport headers, reordered robust VSB data, and multiplexed ATSC Reed / Solomon parity bytes with transport header packets, ATSC data, and Reed / Solomon parity bytes from ATSC. The ATSC Reed / Solomon parity bytes for the robust VSB data are calculated based on the reordered robust VSB data. Also, the interleaver 108 changes the ordering of the robust VSB data, so that the robust VSB data at the output of the interleaver 108 is again robust VSB data ordinarily ordered. Also, interleaver 108 disperses the transport headers, and the ATSC Reed / Solomon parity bytes, and the ATSC data. These data are encoded at 2/3 rate by internal encoder 110 of 2/3 batch of twelve tracks and is transmitted. The transmitted robust VSB data is in normal order, that is, in order provided at the output of the small block interleaver 88. This normal order allows the robust VSB receiver to avoid the delay caused by the deinterleaver 52 and the interleaver 62 of the receiver 14 of robust VSB.

As shown in Figure 8, a standard ATSC receiver 120 includes an internal decoder 122 of 2/3 rate 2/3 rate that decodes the transmitted data to provide a group of output data comprising robust data ordinarily ordered with transport headers interleaved, ATSC data, and ATSC Reed / Solomon parity bytes located according to the ATSC convolutional byte collation provided by interleaver 108. A deintercalator 124 from ATSC restores

<img file="AR042249A2_D0013.tif" />

transport headers, ATSC data, and ATSC Reed / Solomon parity bytes to their “packaged” transport positions. Also, the ATSC deinterleaver 124 converts the robust VSB data ordinarily reordered into robust VSB data.

This rearranged form allows the ATSC Reed / Solomon decoder 126 of the standard ATSC receiver 120 to correctly test the parity for robuta VSB data packets. The standard ATSC receiver 120 can then read the robust VSB data packet transport headers and preferably discard the robust VSB data packets at 128 based on their packet identifications.

As shown in Figure 9, a robust VSB receiver 130 includes an external decoder 132 of 2/3 rate of twelve transient output paths. (A permanent output 2/3 decoder will result in a considerable loss of coding gain). The output of the internal decoder 132 of 2/3 rate of twelve transient output routes comprises robust VSB data ordinarily ordered, with rearranged ATSC data, transport headers, and ATSC Reed / Solomon parity symbols scattered within the data of robust VSB at locations indicated by a discard control line 134 described below. A discard block 136, under the control of the discard control line 134, discards the reordered ATSC data, transport headings, and ATSC Reed / Solomon parity symbols.

The small block deinterleaver 138 deinterleaves the robust VSB data. The small block deinterleaver 138 has a relatively low delay time. This deinterleaver disperses possible batch errors in the robust VSB data at the output of internal decoder 132 of 2/3 rate of twelve output routes. The robust VSB data ordered is usually

<img file="AR042249A2_D0014.tif" />

decoded in terms of bits by an external decoder 140 that also packs the robust VSB data in bytes. The extension information that indicates to the external decoder 140 what decoding rate is used and in what data is provided to the external decoder 140 in an Rmapa data input - Neither the deinterleaver 52 nor the interleaver 62 are needed in the robust VSB receiver 130 allowing for general feedback delay lower to the follower and / or phase compensator. External decoded data can be used, for example, by an improved slice predictor 142 to generate feedback to the follower and / or phase compensator. If desired, the feedback can be blocked, or the stage size of the compensating gradient algorithm can be adjusted proportionally to the reliability of the decoded data.

The useful information of the robust VSB data packet decoded by the external decoder 140 is uninterleaved by a deinterleaver 144 (which is the inverse of the interleaver 84) and is decoded in Reed / Solomon by a Reed / Solomon decoder 146 (corresponding to the Reed / Solomon 82 encoder) in order to reconstruct the original uncoded auxiliary data supplied to the Reed / Solomon 82 encoder in Figure 7.

As stipulated in the ATSC standard, a table comprises a plurality of segments, each of which contains a predetermined number of bytes. The first segment of a frame is a frame synchronization segment, the other segment remaining in a frame are data segments. While robust VSB data can be transmitted in segments or in partial segments, it is convenient to transmit robust VSB data in pairs of segments. The robust VSB map shown above indicates that pairs of segments contain robust VSB data so that discard block 136 can correctly discard the reordered ATSC data before

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Reordered ATSC data can reach external encoder 140. Transport headers and ATSC Reed / Solomon parity data for all segments (robust VBS and ATSC) must also be discarded by discard block 136.

A conceptually simple circuit for generating the appropriate control signal on the discard control line 134 to control this discard function is shown in Figure 10, together with the relevant portion of the robust VSB receiver 130. The robust VSB receiver 130 receives map information 8the method for transmitting and receiving this map information is described below) to instruct a generator 150 of dummy segments when constructing dummy 207 byte segments. The dummy segment generator 150 also uses the tuning signal of the frame. For each ATSC dummy segment, the dummy segment generator 150 sets all bytes to FF. For each robust VSB data dummy segment, the dummy segment generator 150 sets the transport header and the Reed / Solomon parity bytes from ATSC to FF. The dummy segment generator 150 sets the rest of the bytes of each dummy segment of robust VSB data to 00.

These dummy segments are fed by the dummy segment generator 150 to an ATSC convolusional byte interleaver 152 whose output is then used to control the discard block 136 which then responds to the FF 00 codes to correctly discard the reordered ATSC data, transport headings, and ATSC Reed / Solomon parity data that are interleaved within the received data stream. Thus, the discard block 136 passes only the robust VSB data.

Figure 11 shows a robust external code VSB transmitter 160

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multiple. The robust VSB transmitter 160 functions similarly to the robust VSB transmitter 80 of Figure 7. The robust VSB transmitter 160 has a first Reed / Solomon encoder 162 which encodes first uncoded auxiliary data by adding bytes of Reed / parity Solomon to the first auxiliary data not coded. A second Reed / Solomon encoder 164 that encodes second uncoded auxiliary data by adding Reed / Solomon parity bytes to the second uncoded auxiliary data, and a third Reed / Solomon 166 encoder that encodes third bytes of uncoded auxiliary data by adding Reed / Solomon parity bytes to third party uncoded auxiliary data. The third non-coded auxiliary data, coded by Reed / Solomon is interleaved by a first interleaver 168, the second uncoded auxiliary data modified by Reed / Solomon is interleaved by a second interleaver 170, and the third uncoded auxiliary data, coded by Reed / Solomon are interspersed by a third interleaver 172. Then, the first uncoded auxiliary data, coded by interleaved Reed / Solomon are coded as regards bits by a first external encoder 174, the second uncoded auxiliary data, coded by interleaved Reed / Solomon are coded as far as refers to bits by a second external encoder 176, and the third auxiliary data not encoded, Interleaved Reed / Solomon encoded are encoded in terms of bit by a third external encoder 178. The output as regards the bit of the first external encoder 174 is interleaved by a first interleaver 180 of the small block, the output as regards the bit of the second external encoder 176 is interleaved by a second interleaver 182 of the small block, and the output as regards the bit of the third external encoder 178 is interleaved by a third interleaver of small blocks 184.

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I

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The first external encoder 174 is a 1/4 rate encoder, the second external encoder 176 is a 1/2 rate encoder, and the third external encoder 178 is a 3/4 rate encoder, although any other combination of these or other external encoders that use different coding rates could be used. The data outputs of the first small block interleaver 180, the second small block interleaver 182, and the third small block interleaver 184 are selected by a multiplexer 186 under the control of a selection input that determines the order in which the Externally encoded data is differently inserted into the frame to be transmitted. The data at the output of multiplexer 186 can be referred to as R (non) data which, as noted above, means robust VSB data normally ordered.

The top three inputs of a multiplexer 190 receive ATSC format packets, each of which has a valid three-byte transport header with a PID number for robust VSB data, 184 bytes that retain the place of VTB data robust dummy, and 20 bytes that retain the dummy place for ATSC Reed / Solomon parity data. The robust VSB data at the upper end input of the multiplexer 190 corresponds to data encoded with a 1/4 rate, from the first external encoder 174. The robust VSB data at the next input of the multiplexer 190 corresponds to data encoded with 1/2 rate, from the second external encoder 176, and the robust VSB data at the next input of the multiplexer 190 corresponds to data encoded with rate 3 / 4, from the third external encoder 178. The data supplied to the lower end input of multiplexer 190 comprises dummy packets of ATSC format each of which has 207 bytes of ATSC data. These dummy ATSC data packages serve as conservative places for

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Actual ATSC data packets to be added downstream of multiplexer 190. The inputs to multiplexer 190 may be selected on a packet basis per package according to the entry in a selection list. This selection is based on the robust VSB data map to be described below.

The output of multiplexer 190 is interleaved by an interleaver 192 in order to achieve a correct convolutional intercalation of ATSC. A data substituent 194 receives both the interleaver 192 output and the multiplexer 186 output. The data substituent 194 replaces any dummy robust VSB data place conservation bit, coming from multiplexer 190 with the next corresponding normally ordered robust VSB data bit coming from multiplexer 186.

The data substituent output 194 contains normally ordered robust VSB data (which is encoded with 1/4 rate, encoded with 1/2 rate, and / or encoded with 3/4 rate, as appropriate (with interleaved transport header ), dummy Reed / Solomon ATSC parity bytes, and dummy ATSC data packet bytes. A convolutional byte deinterleaver 196 (as described in the ATSC standard) deinterleaves the output of the data substituent 194 to thereby effectively repackage the data as transport header packets, the robust VSB data reordered (encoded with 1/4 rate , coded with 1/2 rate, and / or coded with 3/4 rate), dummy Reed / Solomon parity bytes, and dummy ATSC data packets. The reordering of the robust VSB data ordinarily results from the deinterleaving of the deinterleaver 196.

The dummy ATSC Reed / Solomon parity bytes, (20 per packet) and the dummy ATSC data packets (207 bytes per packet) are discarded in 198 in a manner similar to that provided by the discard control line 134 and the discard block 136 of Figure 9. The robust VSB packages

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Remaining, each of which includes a transport header and reordered robust VSB data, are multiplexed by a multiplexer 200 with reai ATSC data packets, each of which contains 187 bytes of a transport header and ATSC data. Any of the inputs to multiplexer 200 can be selected on a package-by-package basis and is supplied to an ATSC transmitter 202. The selection by multiplexer 200 on which input to be passed to ATSC transmitter 202 is based on the robust VSB map to be described below.

The ATSC transmitter 202 typically includes a Reed / Solomon 204 encoder, an interleaver 206, and an internal encoder 208 of 2/3 rate 2/3, all operating in accordance with the ATSC standard. The Reed / Solomon 204 encoder produces transport header packets, reordered robust VSB data, and multiplexed ATSC Reed / Solomon parity bytes with transport header packets, ATSC data, and Reed / Solomon parity bytes from ATSC. The ATSC Reed / Solomon parity bytes for robust VSB data are calculated based on the reordered robust VSB data. Also, interleaver 206 changes the ordering of the robust VSB data so that the robust VSB data at the output of the interleaver 206 is again robust VSB data ordinarily ordered. Also, interleaver 206 disperses the transport header bytes, the ATSC Reed / Solomon parity bytes, and the ATSC data. These data are coded with batches of 2/3 by internal encoder 208 of 2/3 rate of twelve tracks and are transmitted. The robust VSB data transmitted is in normal order, that is, the order provided at the output of multiplexer 186. This normal data order allows the robust VSB receiver to avoid the delay caused by the deinterleaver 52 and the interleaver 62.

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-20,

Λ.-You

As noted above, an ATSC frame compferidetijn frame synchronization segment and a plurality of data segments, and, for convenience, robust VSB data is packed into groups of four segments. More specifically, Figure 12 shows an example of four data segments that can be used in a frame to transmit robust VSB data that is encoded with 1/2 rate. Figure 13 shows an example of four data segments that can be used in a frame to transmit robust VSB data that is encoded with 1/4 rate, and Figure 14 shows an example of four data segments that can be used in a frame to transmit robust VSB data that is encoded with 3/4 rate. These examples represent the table before interleaver 108, and assume that each group of four robust VSB data segments contains an integral number of robust Reed / Solomon encoded blocks, each of which has a length of 184 bytes, of the which 20 bytes are parity bytes.

In the case of an external 1/2 rate code, Figure 12 shows that the external encoder produces two bits for each input bit. A robust VSB data packet is packed as a RVSB Reed / Solomon block to a pair of data segment (one bit per sign) so that, for an external 1/2 rate code, four segments contain two blocks robust Reed / Solomon coded. As shown in Figure 13, in the case of an external 1/4 rate code, the external encoder produces four bits for each input bit. The robust VSB data is packed as one RVSB Reed / Solomon block for every four data segments (1/2 bits per symbol) so that, for an external 1/4 rate code, four segments contain an encoded block from Reed / Solomon robust. As shown in Figure 14, in the case of an external code of 3/4 rate, the external encoder

<img file="AR042249A2_D0023.tif" />

It produces 4 bits for every 3 input bits. In this case, the transmitted JJ and the byte limits do not always correspond. However, three complete RVSB Reed / Solomon blocks will pack exactly within four data segments (1.5 bits per symbol) so that, for an external 3/4 rate code, four segments contain three Reed encoded blocks / Robust Solomon. Accordingly, Figures 12, 13 and 14 can be represented by the following table:

<td>S</td><td>X</td><td>Y</td>

<td> 1/2</td><td> 1</td><td> 2</td>

<td> 1/4</td><td> 1</td><td> 4</td>

<td> 3/4</td><td> 3</td><td> 4</td>

where X represents the amount of blocks encoded by robust Reed / Solomon and Y represents the number of segments of frames that are required to contain the corresponding amount X of blocks encoded by robust Reed / Solomon.

However, it should be understood that other coding rates can be used in conjunction with the present invention, and, therefore, the table indicated above will change depending on the particular coding rate used.

The interleavers 18, 84, 168, 170 and 172 are shown in greater detail in Figure 15, and the deinterleaders 58 and 144 are shown in greater detail in Figure 16, assuming that a sturdy Reed / Solomon encoded block is chosen so that it has a length of 184 bytes. Interleavers 18, 84, 168, 170 and 172 are convolutional interleavers of B = 46, m = 4, N = 184 that interleave in terms of bits with the robust VSB data. This scheme

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Interleaving is the same as the ATSC interleaving scheme described in ATSC Digital Television Standard A / 53 and the guide for the use of ATSC Digital Television Standard A / 54, except that parameter B for the interleaver robust is 46 instead of 52, and parameter N is 184 instead of 208. This interleaver is needed so that a robust VSB receiver can deal with prolonged runs of noise in the channel even if the ATSC deinterleaver is bypassed as shown in Figure 9.

As shown in Figure 16, the deinterlealers 58 and 144 are convolutional deinterlealers B = 46, M = 4, N = 184 which deinterlealate in terms of bits the robust VSB data. This deinterleaving scheme is also the same as the ATSC deinterleaving scheme described in the ATSC Standard Digital Television Standard A / 53 and the ATSC Standard A / 54 Standard Television Standard Guide, except that Parameter B for the robust deinterleaver is 46 instead of 52 and parameter N is 184 instead of 208.

Because the robust VSB Reed / Solomon block comprises 184 bytes, and because an integral amount of robust VSB Reed / Solomon blocks are in a data frame, the amount of robust VSB data bytes plus bytes of Robust VSB Reed / Solomon parity in a pair of data is always equally divisible by 46. Therefore, the frame synchronization segment can be used as a synchronizer for deinterleaders 58 and 144 (D_r) at the receiver, regardless of the value of G (to be described below). In frame synchronization, the interlocking switches are forced to the upper positions. The deinterleaders 58 and 144 are deinterleavers in terms of bytes.

- Data Mapping -23-

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As noted above, each data frame may contain a mixture of robust VSB data segments and ATSC data segments (not robustly encoded). Also, robust VSB data may contain data encoded with a mixture of coding rates. The robust VSB receiver 14 or 130 must have a robust VSB map indicating which segments are encoded with robust VSB and which external code is used for robust VSB encoding so that the robust VSB receiver 14 or 130 can correctly process the data of robust VSB and discard ATSC data. Robust VSB transmitters 10, 80 and 160 also use the robust VSB map to control their corresponding multiplexing and discard functions. This robust VSB map is transmitted by the robust VSB transmitter 10, 80 or 160 to the robust VSB receiver 14 or 130 along with all other data in a manner described below.

The presence, quantity, and location of robust VSB data in a data box encoded with a particular external code are indicated by one or more numbers S_c which appear as two-level data in the frame synchronization segment of the data frame. As is known, the frame synchronization segment is the first segment in a frame. Thus, for the external codes described above (1/4 rate, 1/2 rate and 3/4 rate) the frame synchronization segment should preferably contain [S1 / 4S1 / 2S3 / 4]. Every S_c (such as S1 / 4 0 S1 / 2 0 S3 / 4) is encoded as eighteen symbols (bits) of two level data. For all three codes, a total of 3x18 = 54 symbols are needed as a robust VSB map definition. These symbols are inserted in the reserved area next to the end of each frame synchronization segment (immediately before the twelve precoding bits). For each group of eighteen bits (bi₈... bi),

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-24 ι&gt; 1 f!

the last six bits (bö... b-ι) represent the number of groups of eight segments (8 segments = 2, 4 or 6 robust VSB data packets depending on the external code) mapped as robust VSB data in the current picture. The twelve preceding bits for feature filter compensation in comb (see Guide for Use of Standard A / 54 of ATSC Standard Digital Television). Therefore, as shown in Figure 18, B bits₆... bi represent the number G, the bits Bw ... bn are the complement of bits b6. . . bi, and the bits Βι₂ . . . bz can alternatively be +1 and -1 (0 any other model).

Assume that S = S1 / 4 / + S1 / 2 + S_3/4. Because 312/8 = 39, 0-39 groups of eight segments can be mapped as robust VSB data or 8 VSB data (ATSC data). Therefore, each S_c It can have a value of 0. .. 39, provided that its sum S is &lt;39.

The robust VSB data segments are preferably distributed as evenly as possible in the data table. For example, if S = 1, then the next eight segments are mapped as robust VSB data segments and all other segments are mapped as ATSC data segments: 1, 40, 79, 118, 157, 196, 235, and 274 If S = 2, then the following sixteen segments are mapped as robust VSB data segments and all other segments are mapped as ATSC data segments: 1, 20, 39, 58, 77, 96, 115, 134, 153 , 172, 191, 210, 229, 248, 267 and 286.

These examples continue to S = 39, where the entire data frame is mapped as robust VSB data segments. For some values ​​of S, the spacing between pairs of segments and robust VSB data is not perfectly uniform. However, for any value of S, the spacing is fixed in advanced and therefore known to all receivers.

If a table contains robust VSB data provided by the three

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External encoders that operate at the rate of 1/4, the rate of 1/2, the rate of 3/4, then the data from these three external encoders can be divided into a table so that, as the RVSB segments , the first 8 x S1 / 4 segments contain the external encoded data of rate 1/4, the next 8 x S1 / 2 segments contain the external encoded data of rate 1/2, and the last 8 x S3 / 4 segments contain the External coded data of 3/4 rate. However, other robust VSB data segment organizations are possible for these three external encoders 0 for any number of other types of external encoders.

Because this robust VSB map is contained in the frame synchronization segment, as noted above, the robust VSB map does not have the same level of coding gain as the robust VSB data. However, the robust VSB map can still be acquired reliably by a robust VSB receiver by correlating the robust VSB map on a number of frames. Therefore, the robust VSB map should not change too often (for example, not more often than every ~ 60 frames).

The mapping method indicated above allows a receiver to acquire reliably and simply the robust VSB map by correlation. Once a receiver has acquired the map, it is convenient for the receiver to instantly and reliably follow changes to the map. To instantly and reliably follow changes to the map, the robust VSB map definition for each external code, excluding comb effect compensation bits, is duplicated in the first block encoded by robust VSB Reed / Solomon of the frame . In addition, there are data indicating (i) when in the future the map will change and (ii) the future definition of the new map. The first robust VSB data packet of a frame for an encoder

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External, therefore, has the structure shown in Figure 27, where the robust VSB map definition data is given by the following: eight bits that designate the current map (only six of these bits are used): eight bits that designate the number of frames until the map changes (1-125; if 0, then there is no change coming); and, eight bits that designate the next map (here too, only six of these bits are used). The remaining portion of the first robust VSB data packet is data. The first RVSB segment in a frame for respective external encoder has the arrangement shown in Figure 17.

In this way, a receiver can follow map changes using reliable robust VSB data. Even if a batch error destroys a number of these frames, the receiver can maintain his own countdown of frames using the amount of frames read from a previously received frame. If the receiver finds at any time that the definition for an external code previously acquired by the frame synchronization correlation does not correspond to the definition for that external code in the first robust VSB data segment, the receiver must restart its process of map acquisition.

RVSB Improved Prediction and Compensation Feedback

The 8 VSB receivers of ATSC make significant use of adaptive compensation and phase monitoring as explained in the ATSC Standard Digital Television Standard A / 53, published by the Advanced Television Systems Committee, in the Guide for the Use of ATSC Standard Digital Television Standard A / 54, also published by the Advanced Television Systems Committee. The RVSB as described above has characteristics that serve to

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improvements in adaptive compensation and phase monitoring.

One of these improvements results from the feedback of delayed reliable estimates of the input symbol level to the adaptive compensator and / or phase follower based on an estimation sequence from an improved Viterbi algorithm. (See “The Viterbi Algorithm,” by GD Fomey Jr., Proc. IEEE, vol 61, p. 268-278, March 1973). This type of feedback avoids the need for "recoding", which has a status initialization problem.

United States of America Patent No. 5,923,711, entitled "Slice Predictor for a Signal Receiver", discloses an ATSC 8 VSB receiver that uses a slice predictor to provide more reliable feedback to the follower of phase or adaptive compensator. This feedback can be made even more reliable by an improved 300 slice predictor system shown in Figure 19. The improved slice predictor system 300 has an internal decoder 302 and an external decoder 304 that function similarly to the internal decoders and external decoders described above.

The cut-off output of the internal decoder 302 operates in a manner similar to that described in United States Patent No. 5,923,711 mentioned above. As explained above, internal decoding 302 is based on an eight-state quaternary framework that includes a precoder. Based on the best trajectory metric at the current time t, the chopper predictor of the internal decoder 302 decides a more probable state at time t. Then, based on the next possible pair of states, four possible planned input levels (of 8 levels) for the next symbol at time t + 1 are selected. For example, as shown in the internal decoder framework in Figure 20, if the state is more

-28 -'W

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probable at time t is state one, the next one is ε [1 5 2 6], therefore, the next level of entry at time t + 1 can be -7, +1, -3, or +5. These next input levels correspond to the decoded bit pairs 00, 10, 01, and 11, respectively.

Similarly, external decoder 304 also finds the best path metric for current time t for the respective fabric. A portion of this screen is shown in Figure 21 for an example of an external decoder and can be applied in general to all three external codes. As shown in Figure 21, two possible pairs of input bits of the external decoder are selected for time t + 1 based on the next pair of possible states. As an example, the two pairs of input bits of the possible external decoder can be 11 or 01. The pair of bits chosen by the external decoder 304 is sent to a prediction booster 306 that selects amplitude levels +5 or - 3 of the set of four levels previously selected by the chopper predictor of internal decoder 302 as the improved slice forecast for time t + 1. Because the prediction of slices of the internal decoder 302 has a delay close to zero, but because the external decoder 304 cannot operate with the same symbol until after the internal decoder 302 has provided a decoded transient output, a module of Delay 308 provides a delay time a little longer than the tracking delay time backward of the internal decoder 302. The slice prediction provided by the prediction improver can be supplied as feedback to a phase follower compensator 310.

With some additional delay time, the external decoder 304 can make a final permanent decision and select a single pair of input bits most likely for the time of t + 1. For example, if 11 is found to be the

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most likely input bit pair to external decoder 304, as determined by its Viterbi Algorithm, this information is sent by external decoder 604 to prediction enhancer 306 which then chooses +5 from the set of four levels and corresponding bit pairs already selected by the chopper predictor of the internal decoder 302. The external code may be a convolutional code or other error correction code. The predictor enhancer 306 is disabled during periods of time when the ATSC data is being received.

A sequence predictor system of maximum probability improved sequence feedback with feedback uses the Viterbi algorithm and is shown in Figure 2 together with other relevant parts of an RBSB receiver. The MLSE improved feedback slicing system 320 has an internal decoder 322 and an external decoder 324 that functions similarly to the internal decoder 302 and the external decoder 304 described above. However, instead of using the chopping prediction output of the internal decoder 302, an improved MLSE module 326 is configured to execute the Viterbi user algorithm on the received signal by operating the rate code 2/3 network eight states (the same fabric as that used by internal decoder 322, including the precoder).

The enhanced MLSE module 326 selects as its next input (i) the signal received from eight noisy levels as it is delayed by a delay module 328 if the next input is a non-RVSB symbol, or (ii) the torque decision output bit of the external encoder 324 (permanent or transient) if the next input is an RVSB symbol. Enhanced MLSE module 326 makes this selection according to the symbol-by-symbol information on the map of

RVSB.

Enhanced MLSE module 326 produces one of eight possible symbols

-30 \&gt;. &gt; v and V; · K

29t / Λ

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and «z / ^ ci / qVA

Η3δ&gt;

and $

~ .Λ- · t Jt &lt;/ f in its prediction of slices, and this prediction of slices (symbol decision) is provided by MLSE module 326 improved as feedback to a phase 330 compensator or follower.

The enhanced MLSE module 326 must follow a more correct path through the eight-state lattice than internal decoder 322 does, because the enhanced MLSE module 326 obtains more reliable input from external decoder 324 when an RVSB symbol available.

The output of the enhanced MLSE module 326 can be a permanent chop decision or a transitional level. Likewise, any indication of symbol reliability from internal decoder 322 or external decoder 324 can be used to change the size of the steps of the compensating LMS algorithm. (See the guide for the use of the ATSC Digital Television Standard A / 54).

An optional predetermined coded orientation sequence may be included in a specified portion of the first RVSB segment of a data field. This sequence is known in advance by both the transmitter and the receiver. During the time that the decoded orientation sequence is produced by the external decoder 324, the input to the enhanced MLSE module 326 is switched to a version stored in the decoded orientation sequence.

Certain modifications of the present invention have been noted above. Other modifications will be apparent to those skilled in the art of the present invention. For example, while the standard ATSC receiver 12 and the robust VSB receiver 14 above are shown as separate receivers, the functions of the standard ATSC receiver 12 and the robust VSB receiver 14 can be

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SvO 'combined into two data paths of a single receiver capable of decoding both types of data (ATSC data and robust VSB data).

Accordingly, the description of the present invention should be interpreted as illustrative only, and for the purpose of revealing to those skilled in the art the best way to carry out the invention. The details can be varied substantially without departing from the spirit of the invention, and the exclusive use of all modifications that are within the scope of the appended claims is reserved.

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Having thus specially described and determined the nature of the present invention and how it should be put into practice, it is claimed to claim as property and exclusive right: