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Diffstat (limited to 'dvb-spec/ISDB-T_and_ISDB-Tsb_with_S2API')
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diff --git a/dvb-spec/ISDB-T_and_ISDB-Tsb_with_S2API b/dvb-spec/ISDB-T_and_ISDB-Tsb_with_S2API new file mode 100644 index 000000000..ef1a05973 --- /dev/null +++ b/dvb-spec/ISDB-T_and_ISDB-Tsb_with_S2API @@ -0,0 +1,209 @@ +This document describes shortly what are the possible parameters in +the Linux DVB-API called "S2API" in order to tune an ISDB-T/ISDB-Tsb +demodulator: + +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. + +The information given here should help application writers to know how +to handle ISDB-T and ISDB-Tsb hardware using the Linux DVB-API. + +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 standard document: +ARIB STD-B31 - "Transmission System for Digital Terrestrial Television +Broadcasting". + +In order to read this document one has to know about 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 so on. + +Parameters used by ISDB-T and ISDB-Tsb. + +Existing parameters +=================== + +a) DTV_BANDCOUNT_HZ + +Help the front-end, for example, to set up base-band-filters. + +Possible values: + +For ISDB-T it should be always 6000000Hz (6MHz) +For ISDB-Tsb it can vary depending on the number of connected segments + +b) DTV_DELIVERY_SYSTEM + +Possible values: SYS_ISDBT + +c) DTV_TRANSMISSION_MODE + +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 + +Possible values: TRANSMISSION_MODE_2K, TRANSMISSION_MODE_8K, + TRANSMISSION_MODE_AUTO, TRANSMISSION_MODE_4K + +If DTV_TRANSMISSION_MODE is set the TRANSMISSION_MODE_AUTO the +hardware will try to find the correct FFT-size (if capable) and use +the TMCC to fill in the missing parameters. + +TRANSMISSION_MODE_4K is added at the same time as the other new parameters. + +d) DTV_GUARD_INTERVAL + +Possible values: GUARD_INTERVAL_1_32, GUARD_INTERVAL_1_16, GUARD_INTERVAL_1_8, + GUARD_INTERVAL_1_4, GUARD_INTERVAL_AUTO + +If DTV_GUARD_INTERVAL is set the GUARD_INTERVAL_AUTO the hardware will +try to find the correct guard interval (if capable) and use the TMCC to fill +in the missing parameters. + +New parameters +============== + +1. DTV_ISDBT_PARTIAL_RECEPTION (1b) + +If DTV_ISDBT_SOUND_BROADCASTING is '0' this bit-field represents whether +the channel is in partial reception mode or not. + +If '1' DTV_ISDBT_LAYERA_* values are assigned to the center segment and +DTV_ISDBT_LAYERA_SEGMENT_COUNT has to be '1'. + +If in addition DTV_ISDBT_SOUND_BROADCASTING is '1' +DTV_ISDBT_PARTIAL_RECEPTION represents whether this ISDB-Tsb channel +is consisting of one segment and layer or three segments and two layers. + +Possible values: 0, 1, -1 (AUTO) + +2. DTV_ISDBT_SOUND_BROADCASTING (1b) + +This field represents whether the other DTV_ISDBT_*-parameters are +referring to an ISDB-T and an ISDB-Tsb channel. (See also +DTV_ISDBT_PARTIAL_RECEPTION). + +Possible values: 0, 1, -1 (AUTO) + +3. DTV_ISDBT_SB_SUBCHANNEL_ID + +This field only applies if DTV_ISDBT_SOUND_BROADCASTING is '1'. + +(Note of the author: This might not be the correct description of the + SUBCHANNEL-ID in all details, but it is my understanding of the technical + background needed to program a device) + +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. + +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. + +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. + +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. + +The DTV_ISDBT_SB_SUBCHANNEL_ID parameter is used to give the +sub-channel ID of the segment to be demodulated. + +Possible values: 0 .. 41, -1 (AUTO) + +4. DTV_ISDBT_SB_SEGMENT_IDX + +This field only applies if DTV_ISDBT_SOUND_BROADCASTING is '1'. + +DTV_ISDBT_SB_SEGMENT_IDX gives the index of the segment to be +demodulated for an ISDB-Tsb channel where several of them are +transmitted in the connected manner. + +Possible values: 0 .. DTV_ISDBT_SB_SEGMENT_COUNT-1 + +Note: This value cannot be determined by an automatic channel search. + +5. DTV_ISDBT_SB_SEGMENT_COUNT + +This field only applies if DTV_ISDBT_SOUND_BROADCASTING is '1'. + +DTV_ISDBT_SB_SEGMENT_COUNT gives the total count of connected ISDB-Tsb +channels. + +Possible values: 1 .. 13 + +Note: This value cannot be determined by an automatic channel search. + +6. Hierarchical layers + +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. + +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. + +6.1 DTV_ISDBT_LAYER_ENABLED (3b) + +Hierarchical reception in ISDB-T is achieved by enabling or disabling +layers in the decoding process. Setting all bits of +DTV_ISDBT_LAYER_ENABLED to '1' forces all layers (if applicable) to be +demodulated. This is the default. + +If the channel is in the partial reception mode +(DTV_ISDBT_PARTIAL_RECEPTION=1) the central segment can be decoded +independently of the other 12 segments. In that mode layer A has to +have a SEGMENT_COUNT of 1. + +In ISDB-Tsb only layer A is used, it can be 1 or 3 in ISDB-Tsb +according to DTV_ISDBT_PARTIAL_RECEPTION. SEGMENT_COUNT must be filled +accordingly. + +Possible values: 0x1, 0x2, 0x4 (|-able) + +DTV_ISDBT_LAYER_ENABLED[0:0] - layer A +DTV_ISDBT_LAYER_ENABLED[1:1] - layer B +DTV_ISDBT_LAYER_ENABLED[2:2] - layer C +DTV_ISDBT_LAYER_ENABLED[31:3] unused + +6.2 DTV_ISDBT_LAYER*_FEC + +Possible values: FEC_AUTO, FEC_1_2, FEC_2_3, FEC_3_4, FEC_5_6, FEC_7_8, + +6.3 DTV_ISDBT_LAYER*_MODULATION + +Possible values: QAM_AUTO, DQPSK, QAM_16, QAM_64, DQPSK + +Note: If layer C is DQPSK layer B has to be DQPSK. If layer B is DQPSK +and DTV_ISDBT_PARTIAL_RECEPTION=0 layer has to be DQPSK. + +6.4 DTV_ISDBT_LAYER*_SEGMENT_COUNT + +Possible values: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, -1 (AUTO) + +Note: Truth table for DTV_ISDBT_SOUND_BROADCASTING and +DTV_ISDBT_PARTIAL_RECEPTION and LAYER*_SEGMENT_COUNT + + PR | SB || layer A width | layer B width | layer C width | total +----+----++---------------+---------------+---------------+------- + 0 | 0 || 1 .. 13 | 1 .. 13 | 1..13 | 13 + 1 | 0 || 1 | 1 .. 13 | 1..13 | 13 + 0 | 1 || 1 | 0 | 0 | 1 + 1 | 1 || 1 | 2 | 0 | 3 + + +6.5 DTV_ISDBT_LAYER*_TIME_INTERLEAVING + +Possible values: 0, 1, 2, 3, -1 (AUTO) + +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. |