Documentation/DocBook/dvb/isdbt.xml

   1 <section id="isdbt">
   2         <title>ISDB-T frontend</title>
   3         <para>This section describes shortly what are the possible parameters in the Linux
   4                 DVB-API called "S2API" and now DVB API 5 in order to tune an ISDB-T/ISDB-Tsb
   5                 demodulator:</para>
   6
   7         <para>This ISDB-T/ISDB-Tsb API extension should reflect all information
   8                 needed to tune any ISDB-T/ISDB-Tsb hardware. Of course it is possible
   9                 that some very sophisticated devices won't need certain parameters to
  10                 tune.</para>
  11
  12         <para>The information given here should help application writers to know how
  13                 to handle ISDB-T and ISDB-Tsb hardware using the Linux DVB-API.</para>
  14
  15         <para>The details given here about ISDB-T and ISDB-Tsb are just enough to
  16                 basically show the dependencies between the needed parameter values,
  17                 but surely some information is left out. For more detailed information
  18                 see the following documents:</para>
  19
  20         <para>ARIB STD-B31 - "Transmission System for Digital Terrestrial
  21                 Television Broadcasting" and</para>
  22         <para>ARIB TR-B14 - "Operational Guidelines for Digital Terrestrial
  23                 Television Broadcasting".</para>
  24
  25         <para>In order to read this document one has to have some knowledge the
  26                 channel structure in ISDB-T and ISDB-Tsb. I.e. it has to be known to
  27                 the reader that an ISDB-T channel consists of 13 segments, that it can
  28                 have up to 3 layer sharing those segments, and things like that.</para>
  29
  30         <para>Parameters used by ISDB-T and ISDB-Tsb.</para>
  31
  32         <section id="isdbt-parms">
  33                 <title>Parameters that are common with DVB-T and ATSC</title>
  34
  35                 <section id="isdbt-freq">
  36                         <title><constant>DTV_FREQUENCY</constant></title>
  37
  38                         <para>Central frequency of the channel.</para>
  39
  40                         <para>For ISDB-T the channels are usally transmitted with an offset of 143kHz. E.g. a
  41                                 valid frequncy could be 474143 kHz. The stepping is bound to the bandwidth of
  42                                 the channel which is 6MHz.</para>
  43
  44                         <para>As in ISDB-Tsb the channel consists of only one or three segments the
  45                                 frequency step is 429kHz, 3*429 respectively. As for ISDB-T the
  46                                 central frequency of the channel is expected.</para>
  47                 </section>
  48
  49                 <section id="isdbt-bw">
  50                         <title><constant>DTV_BANDWIDTH_HZ</constant> (optional)</title>
  51
  52                         <para>Possible values:</para>
  53
  54                         <para>For ISDB-T it should be always 6000000Hz (6MHz)</para>
  55                         <para>For ISDB-Tsb it can vary depending on the number of connected segments</para>
  56
  57                         <para>Note: Hardware specific values might be given here, but standard
  58                                 applications should not bother to set a value to this field as
  59                                 standard demods are ignoring it anyway.</para>
  60
  61                         <para>Bandwidth in ISDB-T is fixed (6MHz) or can be easily derived from
  62                                 other parameters (DTV_ISDBT_SB_SEGMENT_IDX,
  63                                 DTV_ISDBT_SB_SEGMENT_COUNT).</para>
  64                 </section>
  65
  66                 <section id="isdbt-delivery-sys">
  67                         <title><constant>DTV_DELIVERY_SYSTEM</constant></title>
  68
  69                         <para>Possible values: <constant>SYS_ISDBT</constant></para>
  70                 </section>
  71
  72                 <section id="isdbt-tx-mode">
  73                         <title><constant>DTV_TRANSMISSION_MODE</constant></title>
  74
  75                         <para>ISDB-T supports three carrier/symbol-size: 8K, 4K, 2K. It is called
  76                                 'mode' in the standard: Mode 1 is 2K, mode 2 is 4K, mode 3 is 8K</para>
  77
  78                         <para>Possible values: <constant>TRANSMISSION_MODE_2K</constant>, <constant>TRANSMISSION_MODE_8K</constant>,
  79                                 <constant>TRANSMISSION_MODE_AUTO</constant>, <constant>TRANSMISSION_MODE_4K</constant></para>
  80
  81                         <para>If <constant>DTV_TRANSMISSION_MODE</constant> is set the <constant>TRANSMISSION_MODE_AUTO</constant> the
  82                                 hardware will try to find the correct FFT-size (if capable) and will
  83                                 use TMCC to fill in the missing parameters.</para>
  84
  85                         <para><constant>TRANSMISSION_MODE_4K</constant> is added at the same time as the other new parameters.</para>
  86                 </section>
  87
  88                 <section id="isdbt-guard-interval">
  89                         <title><constant>DTV_GUARD_INTERVAL</constant></title>
  90
  91                         <para>Possible values: <constant>GUARD_INTERVAL_1_32</constant>, <constant>GUARD_INTERVAL_1_16</constant>, <constant>GUARD_INTERVAL_1_8</constant>,
  92                                 <constant>GUARD_INTERVAL_1_4</constant>, <constant>GUARD_INTERVAL_AUTO</constant></para>
  93
  94                         <para>If <constant>DTV_GUARD_INTERVAL</constant> is set the <constant>GUARD_INTERVAL_AUTO</constant> the hardware will
  95                                 try to find the correct guard interval (if capable) and will use TMCC to fill
  96                                 in the missing parameters.</para>
  97                 </section>
  98         </section>
  99         <section id="isdbt-new-parms">
 100                 <title>ISDB-T only parameters</title>
 101
 102                 <section id="isdbt-part-rec">
 103                         <title><constant>DTV_ISDBT_PARTIAL_RECEPTION</constant></title>
 104
 105                         <para><constant>If DTV_ISDBT_SOUND_BROADCASTING</constant> is '0' this bit-field represents whether
 106                                 the channel is in partial reception mode or not.</para>
 107
 108                         <para>If '1' <constant>DTV_ISDBT_LAYERA_*</constant> values are assigned to the center segment and
 109                                 <constant>DTV_ISDBT_LAYERA_SEGMENT_COUNT</constant> has to be '1'.</para>
 110
 111                         <para>If in addition <constant>DTV_ISDBT_SOUND_BROADCASTING</constant> is '1'
 112                                 <constant>DTV_ISDBT_PARTIAL_RECEPTION</constant> represents whether this ISDB-Tsb channel
 113                                 is consisting of one segment and layer or three segments and two layers.</para>
 114
 115                         <para>Possible values: 0, 1, -1 (AUTO)</para>
 116                 </section>
 117
 118                 <section id="isdbt-sound-bcast">
 119                         <title><constant>DTV_ISDBT_SOUND_BROADCASTING</constant></title>
 120
 121                         <para>This field represents whether the other DTV_ISDBT_*-parameters are
 122                                 referring to an ISDB-T and an ISDB-Tsb channel. (See also
 123                                 <constant>DTV_ISDBT_PARTIAL_RECEPTION</constant>).</para>
 124
 125                         <para>Possible values: 0, 1, -1 (AUTO)</para>
 126                 </section>
 127
 128                 <section id="isdbt-sb-ch-id">
 129                         <title><constant>DTV_ISDBT_SB_SUBCHANNEL_ID</constant></title>
 130
 131                         <para>This field only applies if <constant>DTV_ISDBT_SOUND_BROADCASTING</constant> is '1'.</para>
 132
 133                         <para>(Note of the author: This might not be the correct description of the
 134                                 <constant>SUBCHANNEL-ID</constant> in all details, but it is my understanding of the technical
 135                                 background needed to program a device)</para>
 136
 137                         <para>An ISDB-Tsb channel (1 or 3 segments) can be broadcasted alone or in a
 138                                 set of connected ISDB-Tsb channels. In this set of channels every
 139                                 channel can be received independently. The number of connected
 140                                 ISDB-Tsb segment can vary, e.g. depending on the frequency spectrum
 141                                 bandwidth available.</para>
 142
 143                         <para>Example: Assume 8 ISDB-Tsb connected segments are broadcasted. The
 144                                 broadcaster has several possibilities to put those channels in the
 145                                 air: Assuming a normal 13-segment ISDB-T spectrum he can align the 8
 146                                 segments from position 1-8 to 5-13 or anything in between.</para>
 147
 148                         <para>The underlying layer of segments are subchannels: each segment is
 149                                 consisting of several subchannels with a predefined IDs. A sub-channel
 150                                 is used to help the demodulator to synchronize on the channel.</para>
 151
 152                         <para>An ISDB-T channel is always centered over all sub-channels. As for
 153                                 the example above, in ISDB-Tsb it is no longer as simple as that.</para>
 154
 155                         <para><constant>The DTV_ISDBT_SB_SUBCHANNEL_ID</constant> parameter is used to give the
 156                                 sub-channel ID of the segment to be demodulated.</para>
 157
 158                         <para>Possible values: 0 .. 41, -1 (AUTO)</para>
 159                 </section>
 160
 161                 <section id="isdbt-sb-seg-idx">
 162
 163                         <title><constant>DTV_ISDBT_SB_SEGMENT_IDX</constant></title>
 164
 165                         <para>This field only applies if <constant>DTV_ISDBT_SOUND_BROADCASTING</constant> is '1'.</para>
 166
 167                         <para><constant>DTV_ISDBT_SB_SEGMENT_IDX</constant> gives the index of the segment to be
 168                                 demodulated for an ISDB-Tsb channel where several of them are
 169                                 transmitted in the connected manner.</para>
 170
 171                         <para>Possible values: 0 .. <constant>DTV_ISDBT_SB_SEGMENT_COUNT</constant> - 1</para>
 172
 173                         <para>Note: This value cannot be determined by an automatic channel search.</para>
 174                 </section>
 175
 176                 <section id="isdbt-sb-seg-cnt">
 177                         <title><constant>DTV_ISDBT_SB_SEGMENT_COUNT</constant></title>
 178
 179                         <para>This field only applies if <constant>DTV_ISDBT_SOUND_BROADCASTING</constant> is '1'.</para>
 180
 181                         <para><constant>DTV_ISDBT_SB_SEGMENT_COUNT</constant> gives the total count of connected ISDB-Tsb
 182                                 channels.</para>
 183
 184                         <para>Possible values: 1 .. 13</para>
 185
 186                         <para>Note: This value cannot be determined by an automatic channel search.</para>
 187                 </section>
 188
 189                 <section id="isdb-hierq-layers">
 190                         <title>Hierarchical layers</title>
 191
 192                         <para>ISDB-T channels can be coded hierarchically. As opposed to DVB-T in
 193                                 ISDB-T hierarchical layers can be decoded simultaneously. For that
 194                                 reason a ISDB-T demodulator has 3 viterbi and 3 reed-solomon-decoders.</para>
 195
 196                         <para>ISDB-T has 3 hierarchical layers which each can use a part of the
 197                                 available segments. The total number of segments over all layers has
 198                                 to 13 in ISDB-T.</para>
 199
 200                         <section id="isdbt-layer-ena">
 201                                 <title><constant>DTV_ISDBT_LAYER_ENABLED</constant></title>
 202
 203                                 <para>Hierarchical reception in ISDB-T is achieved by enabling or disabling
 204                                         layers in the decoding process. Setting all bits of
 205                                         <constant>DTV_ISDBT_LAYER_ENABLED</constant> to '1' forces all layers (if applicable) to be
 206                                         demodulated. This is the default.</para>
 207
 208                                 <para>If the channel is in the partial reception mode
 209                                         (<constant>DTV_ISDBT_PARTIAL_RECEPTION</constant> = 1) the central segment can be decoded
 210                                         independently of the other 12 segments. In that mode layer A has to
 211                                         have a <constant>SEGMENT_COUNT</constant> of 1.</para>
 212
 213                                 <para>In ISDB-Tsb only layer A is used, it can be 1 or 3 in ISDB-Tsb
 214                                         according to <constant>DTV_ISDBT_PARTIAL_RECEPTION</constant>. <constant>SEGMENT_COUNT</constant> must be filled
 215                                         accordingly.</para>
 216
 217                                 <para>Possible values: 0x1, 0x2, 0x4 (|-able)</para>
 218
 219                                 <para><constant>DTV_ISDBT_LAYER_ENABLED[0:0]</constant> - layer A</para>
 220                                 <para><constant>DTV_ISDBT_LAYER_ENABLED[1:1]</constant> - layer B</para>
 221                                 <para><constant>DTV_ISDBT_LAYER_ENABLED[2:2]</constant> - layer C</para>
 222                                 <para><constant>DTV_ISDBT_LAYER_ENABLED[31:3]</constant> unused</para>
 223                         </section>
 224
 225                         <section id="isdbt-layer-fec">
 226                                 <title><constant>DTV_ISDBT_LAYER*_FEC</constant></title>
 227
 228                                 <para>Possible values: <constant>FEC_AUTO</constant>, <constant>FEC_1_2</constant>, <constant>FEC_2_3</constant>, <constant>FEC_3_4</constant>, <constant>FEC_5_6</constant>, <constant>FEC_7_8</constant></para>
 229                         </section>
 230
 231                         <section id="isdbt-layer-mod">
 232                                 <title><constant>DTV_ISDBT_LAYER*_MODULATION</constant></title>
 233
 234                                 <para>Possible values: <constant>QAM_AUTO</constant>, QP<constant>SK, QAM_16</constant>, <constant>QAM_64</constant>, <constant>DQPSK</constant></para>
 235
 236                                 <para>Note: If layer C is <constant>DQPSK</constant> layer B has to be <constant>DQPSK</constant>. If layer B is <constant>DQPSK</constant>
 237                                         and <constant>DTV_ISDBT_PARTIAL_RECEPTION</constant>=0 layer has to be <constant>DQPSK</constant>.</para>
 238                         </section>
 239
 240                         <section id="isdbt-layer-seg-cnt">
 241                                 <title><constant>DTV_ISDBT_LAYER*_SEGMENT_COUNT</constant></title>
 242
 243                                 <para>Possible values: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, -1 (AUTO)</para>
 244
 245                                 <para>Note: Truth table for <constant>DTV_ISDBT_SOUND_BROADCASTING</constant> and
 246                                         <constant>DTV_ISDBT_PARTIAL_RECEPTION</constant> and <constant>LAYER</constant>*_SEGMENT_COUNT</para>
 247
 248                                 <informaltable id="isdbt-layer_seg-cnt-table">
 249                                         <tgroup cols="6">
 250
 251                                                 <tbody>
 252                                                         <row>
 253                                                                 <entry>PR</entry>
 254                                                                 <entry>SB</entry>
 255                                                                 <entry>Layer A width</entry>
 256                                                                 <entry>Layer B width</entry>
 257                                                                 <entry>Layer C width</entry>
 258                                                                 <entry>total width</entry>
 259                                                         </row>
 260
 261                                                         <row>
 262                                                                 <entry>0</entry>
 263                                                                 <entry>0</entry>
 264                                                                 <entry>1 .. 13</entry>
 265                                                                 <entry>1 .. 13</entry>
 266                                                                 <entry>1 .. 13</entry>
 267                                                                 <entry>13</entry>
 268                                                         </row>
 269
 270                                                         <row>
 271                                                                 <entry>1</entry>
 272                                                                 <entry>0</entry>
 273                                                                 <entry>1</entry>
 274                                                                 <entry>1 .. 13</entry>
 275                                                                 <entry>1 .. 13</entry>
 276                                                                 <entry>13</entry>
 277                                                         </row>
 278
 279                                                         <row>
 280                                                                 <entry>0</entry>
 281                                                                 <entry>1</entry>
 282                                                                 <entry>1</entry>
 283                                                                 <entry>0</entry>
 284                                                                 <entry>0</entry>
 285                                                                 <entry>1</entry>
 286                                                         </row>
 287
 288                                                         <row>
 289                                                                 <entry>1</entry>
 290                                                                 <entry>1</entry>
 291                                                                 <entry>1</entry>
 292                                                                 <entry>2</entry>
 293                                                                 <entry>0</entry>
 294                                                                 <entry>13</entry>
 295                                                         </row>
 296                                                 </tbody>
 297
 298                                         </tgroup>
 299                                 </informaltable>
 300
 301                         </section>
 302
 303                         <section id="isdbt_layer_t_interl">
 304                                 <title><constant>DTV_ISDBT_LAYER*_TIME_INTERLEAVING</constant></title>
 305
 306                                 <para>Possible values: 0, 1, 2, 3, -1 (AUTO)</para>
 307
 308                                 <para>Note: The real inter-leaver depth-names depend on the mode (fft-size); the values
 309                                         here are referring to what can be found in the TMCC-structure -
 310                                         independent of the mode.</para>
 311                         </section>
 312                 </section>
 313         </section>
 314 </section>