dvbproperty.xml 12.5 KB
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<section id="isdbt">
	<title>ISDB-T frontend</title>
	<para>This section describes shortly what are the possible parameters in the Linux
		DVB-API called "S2API" and now DVB API 5 in order to tune an ISDB-T/ISDB-Tsb
		demodulator:</para>

	<para>This ISDB-T/ISDB-Tsb API extension should reflect all information
		needed to tune any ISDB-T/ISDB-Tsb hardware. Of course it is possible
		that some very sophisticated devices won't need certain parameters to
		tune.</para>

	<para>The information given here should help application writers to know how
		to handle ISDB-T and ISDB-Tsb hardware using the Linux DVB-API.</para>

	<para>The details given here about ISDB-T and ISDB-Tsb are just enough to
		basically show the dependencies between the needed parameter values,
		but surely some information is left out. For more detailed information
		see the following documents:</para>

	<para>ARIB STD-B31 - "Transmission System for Digital Terrestrial
		Television Broadcasting" and</para>
	<para>ARIB TR-B14 - "Operational Guidelines for Digital Terrestrial
		Television Broadcasting".</para>

	<para>In order to read this document one has to have some knowledge the
		channel structure in ISDB-T and ISDB-Tsb. I.e. it has to be known to
		the reader that an ISDB-T channel consists of 13 segments, that it can
		have up to 3 layer sharing those segments, and things like that.</para>

	<para>Parameters used by ISDB-T and ISDB-Tsb.</para>

	<section id="isdbt-parms">
		<title>Parameters that are common with DVB-T and ATSC</title>

		<section id="isdbt-freq">
			<title><constant>DTV_FREQUENCY</constant></title>

			<para>Central frequency of the channel.</para>

			<para>For ISDB-T the channels are usally transmitted with an offset of 143kHz. E.g. a
				valid frequncy could be 474143 kHz. The stepping is bound to the bandwidth of
				the channel which is 6MHz.</para>

			<para>As in ISDB-Tsb the channel consists of only one or three segments the
				frequency step is 429kHz, 3*429 respectively. As for ISDB-T the
				central frequency of the channel is expected.</para>
		</section>

		<section id="isdbt-bw">
			<title><constant>DTV_BANDWIDTH_HZ</constant> (optional)</title>

			<para>Possible values:</para>

			<para>For ISDB-T it should be always 6000000Hz (6MHz)</para>
			<para>For ISDB-Tsb it can vary depending on the number of connected segments</para>

			<para>Note: Hardware specific values might be given here, but standard
				applications should not bother to set a value to this field as
				standard demods are ignoring it anyway.</para>

			<para>Bandwidth in ISDB-T is fixed (6MHz) or can be easily derived from
				other parameters (DTV_ISDBT_SB_SEGMENT_IDX,
				DTV_ISDBT_SB_SEGMENT_COUNT).</para>
		</section>

		<section id="isdbt-delivery-sys">
			<title><constant>DTV_DELIVERY_SYSTEM</constant></title>

			<para>Possible values: <constant>SYS_ISDBT</constant></para>
		</section>

		<section id="isdbt-tx-mode">
			<title><constant>DTV_TRANSMISSION_MODE</constant></title>

			<para>ISDB-T supports three carrier/symbol-size: 8K, 4K, 2K. It is called
				'mode' in the standard: Mode 1 is 2K, mode 2 is 4K, mode 3 is 8K</para>

			<para>Possible values: <constant>TRANSMISSION_MODE_2K</constant>, <constant>TRANSMISSION_MODE_8K</constant>,
				<constant>TRANSMISSION_MODE_AUTO</constant>, <constant>TRANSMISSION_MODE_4K</constant></para>

			<para>If <constant>DTV_TRANSMISSION_MODE</constant> is set the <constant>TRANSMISSION_MODE_AUTO</constant> the
				hardware will try to find the correct FFT-size (if capable) and will
				use TMCC to fill in the missing parameters.</para>

			<para><constant>TRANSMISSION_MODE_4K</constant> is added at the same time as the other new parameters.</para>
		</section>

		<section id="isdbt-guard-interval">
			<title><constant>DTV_GUARD_INTERVAL</constant></title>

			<para>Possible values: <constant>GUARD_INTERVAL_1_32</constant>, <constant>GUARD_INTERVAL_1_16</constant>, <constant>GUARD_INTERVAL_1_8</constant>,
				<constant>GUARD_INTERVAL_1_4</constant>, <constant>GUARD_INTERVAL_AUTO</constant></para>

			<para>If <constant>DTV_GUARD_INTERVAL</constant> is set the <constant>GUARD_INTERVAL_AUTO</constant> the hardware will
				try to find the correct guard interval (if capable) and will use TMCC to fill
				in the missing parameters.</para>
		</section>
	</section>
99 100
	<section id="isdbt-new-parms">
		<title>ISDB-T only parameters</title>
101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124

		<section id="isdbt-part-rec">
			<title><constant>DTV_ISDBT_PARTIAL_RECEPTION</constant></title>

			<para><constant>If DTV_ISDBT_SOUND_BROADCASTING</constant> is '0' this bit-field represents whether
				the channel is in partial reception mode or not.</para>

			<para>If '1' <constant>DTV_ISDBT_LAYERA_*</constant> values are assigned to the center segment and
				<constant>DTV_ISDBT_LAYERA_SEGMENT_COUNT</constant> has to be '1'.</para>

			<para>If in addition <constant>DTV_ISDBT_SOUND_BROADCASTING</constant> is '1'
				<constant>DTV_ISDBT_PARTIAL_RECEPTION</constant> represents whether this ISDB-Tsb channel
				is consisting of one segment and layer or three segments and two layers.</para>

			<para>Possible values: 0, 1, -1 (AUTO)</para>
		</section>

		<section id="isdbt-sound-bcast">
			<title><constant>DTV_ISDBT_SOUND_BROADCASTING</constant></title>

			<para>This field represents whether the other DTV_ISDBT_*-parameters are
				referring to an ISDB-T and an ISDB-Tsb channel. (See also
				<constant>DTV_ISDBT_PARTIAL_RECEPTION</constant>).</para>

125
			<para>Possible values: 0, 1, -1 (AUTO)</para>
126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314
		</section>

		<section id="isdbt-sb-ch-id">
			<title><constant>DTV_ISDBT_SB_SUBCHANNEL_ID</constant></title>

			<para>This field only applies if <constant>DTV_ISDBT_SOUND_BROADCASTING</constant> is '1'.</para>

			<para>(Note of the author: This might not be the correct description of the
				<constant>SUBCHANNEL-ID</constant> in all details, but it is my understanding of the technical
				background needed to program a device)</para>

			<para>An ISDB-Tsb channel (1 or 3 segments) can be broadcasted alone or in a
				set of connected ISDB-Tsb channels. In this set of channels every
				channel can be received independently. The number of connected
				ISDB-Tsb segment can vary, e.g. depending on the frequency spectrum
				bandwidth available.</para>

			<para>Example: Assume 8 ISDB-Tsb connected segments are broadcasted. The
				broadcaster has several possibilities to put those channels in the
				air: Assuming a normal 13-segment ISDB-T spectrum he can align the 8
				segments from position 1-8 to 5-13 or anything in between.</para>

			<para>The underlying layer of segments are subchannels: each segment is
				consisting of several subchannels with a predefined IDs. A sub-channel
				is used to help the demodulator to synchronize on the channel.</para>

			<para>An ISDB-T channel is always centered over all sub-channels. As for
				the example above, in ISDB-Tsb it is no longer as simple as that.</para>

			<para><constant>The DTV_ISDBT_SB_SUBCHANNEL_ID</constant> parameter is used to give the
				sub-channel ID of the segment to be demodulated.</para>

			<para>Possible values: 0 .. 41, -1 (AUTO)</para>
		</section>

		<section id="isdbt-sb-seg-idx">

			<title><constant>DTV_ISDBT_SB_SEGMENT_IDX</constant></title>

			<para>This field only applies if <constant>DTV_ISDBT_SOUND_BROADCASTING</constant> is '1'.</para>

			<para><constant>DTV_ISDBT_SB_SEGMENT_IDX</constant> gives the index of the segment to be
				demodulated for an ISDB-Tsb channel where several of them are
				transmitted in the connected manner.</para>

			<para>Possible values: 0 .. <constant>DTV_ISDBT_SB_SEGMENT_COUNT</constant> - 1</para>

			<para>Note: This value cannot be determined by an automatic channel search.</para>
		</section>

		<section id="isdbt-sb-seg-cnt">
			<title><constant>DTV_ISDBT_SB_SEGMENT_COUNT</constant></title>

			<para>This field only applies if <constant>DTV_ISDBT_SOUND_BROADCASTING</constant> is '1'.</para>

			<para><constant>DTV_ISDBT_SB_SEGMENT_COUNT</constant> gives the total count of connected ISDB-Tsb
				channels.</para>

			<para>Possible values: 1 .. 13</para>

			<para>Note: This value cannot be determined by an automatic channel search.</para>
		</section>

		<section id="isdb-hierq-layers">
			<title>Hierarchical layers</title>

			<para>ISDB-T channels can be coded hierarchically. As opposed to DVB-T in
				ISDB-T hierarchical layers can be decoded simultaneously. For that
				reason a ISDB-T demodulator has 3 viterbi and 3 reed-solomon-decoders.</para>

			<para>ISDB-T has 3 hierarchical layers which each can use a part of the
				available segments. The total number of segments over all layers has
				to 13 in ISDB-T.</para>

			<section id="isdbt-layer-ena">
				<title><constant>DTV_ISDBT_LAYER_ENABLED</constant></title>

				<para>Hierarchical reception in ISDB-T is achieved by enabling or disabling
					layers in the decoding process. Setting all bits of
					<constant>DTV_ISDBT_LAYER_ENABLED</constant> to '1' forces all layers (if applicable) to be
					demodulated. This is the default.</para>

				<para>If the channel is in the partial reception mode
					(<constant>DTV_ISDBT_PARTIAL_RECEPTION</constant> = 1) the central segment can be decoded
					independently of the other 12 segments. In that mode layer A has to
					have a <constant>SEGMENT_COUNT</constant> of 1.</para>

				<para>In ISDB-Tsb only layer A is used, it can be 1 or 3 in ISDB-Tsb
					according to <constant>DTV_ISDBT_PARTIAL_RECEPTION</constant>. <constant>SEGMENT_COUNT</constant> must be filled
					accordingly.</para>

				<para>Possible values: 0x1, 0x2, 0x4 (|-able)</para>

				<para><constant>DTV_ISDBT_LAYER_ENABLED[0:0]</constant> - layer A</para>
				<para><constant>DTV_ISDBT_LAYER_ENABLED[1:1]</constant> - layer B</para>
				<para><constant>DTV_ISDBT_LAYER_ENABLED[2:2]</constant> - layer C</para>
				<para><constant>DTV_ISDBT_LAYER_ENABLED[31:3]</constant> unused</para>
			</section>

			<section id="isdbt-layer-fec">
				<title><constant>DTV_ISDBT_LAYER*_FEC</constant></title>

				<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>
			</section>

			<section id="isdbt-layer-mod">
				<title><constant>DTV_ISDBT_LAYER*_MODULATION</constant></title>

				<para>Possible values: <constant>QAM_AUTO</constant>, QP<constant>SK, QAM_16</constant>, <constant>QAM_64</constant>, <constant>DQPSK</constant></para>

				<para>Note: If layer C is <constant>DQPSK</constant> layer B has to be <constant>DQPSK</constant>. If layer B is <constant>DQPSK</constant>
					and <constant>DTV_ISDBT_PARTIAL_RECEPTION</constant>=0 layer has to be <constant>DQPSK</constant>.</para>
			</section>

			<section id="isdbt-layer-seg-cnt">
				<title><constant>DTV_ISDBT_LAYER*_SEGMENT_COUNT</constant></title>

				<para>Possible values: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, -1 (AUTO)</para>

				<para>Note: Truth table for <constant>DTV_ISDBT_SOUND_BROADCASTING</constant> and
					<constant>DTV_ISDBT_PARTIAL_RECEPTION</constant> and <constant>LAYER</constant>*_SEGMENT_COUNT</para>

				<informaltable id="isdbt-layer_seg-cnt-table">
					<tgroup cols="6">

						<tbody>
							<row>
								<entry>PR</entry>
								<entry>SB</entry>
								<entry>Layer A width</entry>
								<entry>Layer B width</entry>
								<entry>Layer C width</entry>
								<entry>total width</entry>
							</row>

							<row>
								<entry>0</entry>
								<entry>0</entry>
								<entry>1 .. 13</entry>
								<entry>1 .. 13</entry>
								<entry>1 .. 13</entry>
								<entry>13</entry>
							</row>

							<row>
								<entry>1</entry>
								<entry>0</entry>
								<entry>1</entry>
								<entry>1 .. 13</entry>
								<entry>1 .. 13</entry>
								<entry>13</entry>
							</row>

							<row>
								<entry>0</entry>
								<entry>1</entry>
								<entry>1</entry>
								<entry>0</entry>
								<entry>0</entry>
								<entry>1</entry>
							</row>

							<row>
								<entry>1</entry>
								<entry>1</entry>
								<entry>1</entry>
								<entry>2</entry>
								<entry>0</entry>
								<entry>13</entry>
							</row>
						</tbody>

					</tgroup>
				</informaltable>

			</section>

			<section id="isdbt_layer_t_interl">
				<title><constant>DTV_ISDBT_LAYER*_TIME_INTERLEAVING</constant></title>

				<para>Possible values: 0, 1, 2, 3, -1 (AUTO)</para>

				<para>Note: The real inter-leaver depth-names depend on the mode (fft-size); the values
					here are referring to what can be found in the TMCC-structure -
					independent of the mode.</para>
			</section>
		</section>
	</section>
</section>