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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>
generated by cgit v1.2.2 (git 2.25.0) at 2025-01-06 01:08:59 -0500