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1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later2 3.. _frontend-stat-properties:4 5******************************6Frontend statistics indicators7******************************8 9The values are returned via ``dtv_property.stat``. If the property is10supported, ``dtv_property.stat.len`` is bigger than zero.11 12For most delivery systems, ``dtv_property.stat.len`` will be 1 if the13stats is supported, and the properties will return a single value for14each parameter.15 16It should be noted, however, that new OFDM delivery systems like ISDB17can use different modulation types for each group of carriers. On such18standards, up to 3 groups of statistics can be provided, and19``dtv_property.stat.len`` is updated to reflect the "global" metrics,20plus one metric per each carrier group (called "layer" on ISDB).21 22So, in order to be consistent with other delivery systems, the first23value at :c:type:`dtv_property.stat.dtv_stats <dtv_stats>` array refers24to the global metric. The other elements of the array represent each25layer, starting from layer A(index 1), layer B (index 2) and so on.26 27The number of filled elements are stored at ``dtv_property.stat.len``.28 29Each element of the ``dtv_property.stat.dtv_stats`` array consists on30two elements:31 32- ``svalue`` or ``uvalue``, where ``svalue`` is for signed values of33 the measure (dB measures) and ``uvalue`` is for unsigned values34 (counters, relative scale)35 36- ``scale`` - Scale for the value. It can be:37 38 - ``FE_SCALE_NOT_AVAILABLE`` - The parameter is supported by the39 frontend, but it was not possible to collect it (could be a40 transitory or permanent condition)41 42 - ``FE_SCALE_DECIBEL`` - parameter is a signed value, measured in43 1/1000 dB44 45 - ``FE_SCALE_RELATIVE`` - parameter is a unsigned value, where 046 means 0% and 65535 means 100%.47 48 - ``FE_SCALE_COUNTER`` - parameter is a unsigned value that counts49 the occurrence of an event, like bit error, block error, or lapsed50 time.51 52 53.. _DTV-STAT-SIGNAL-STRENGTH:54 55DTV_STAT_SIGNAL_STRENGTH56========================57 58Indicates the signal strength level at the analog part of the tuner or59of the demod.60 61Possible scales for this metric are:62 63- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the64 measurement was not complete yet.65 66- ``FE_SCALE_DECIBEL`` - signal strength is in 0.001 dBm units, power67 measured in miliwatts. This value is generally negative.68 69- ``FE_SCALE_RELATIVE`` - The frontend provides a 0% to 100%70 measurement for power (actually, 0 to 65535).71 72 73.. _DTV-STAT-CNR:74 75DTV_STAT_CNR76============77 78Indicates the Signal to Noise ratio for the main carrier.79 80Possible scales for this metric are:81 82- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the83 measurement was not complete yet.84 85- ``FE_SCALE_DECIBEL`` - Signal/Noise ratio is in 0.001 dB units.86 87- ``FE_SCALE_RELATIVE`` - The frontend provides a 0% to 100%88 measurement for Signal/Noise (actually, 0 to 65535).89 90 91.. _DTV-STAT-PRE-ERROR-BIT-COUNT:92 93DTV_STAT_PRE_ERROR_BIT_COUNT94============================95 96Measures the number of bit errors before the forward error correction97(FEC) on the inner coding block (before Viterbi, LDPC or other inner98code).99 100This measure is taken during the same interval as101``DTV_STAT_PRE_TOTAL_BIT_COUNT``.102 103In order to get the BER (Bit Error Rate) measurement, it should be104divided by105:ref:`DTV_STAT_PRE_TOTAL_BIT_COUNT <DTV-STAT-PRE-TOTAL-BIT-COUNT>`.106 107This measurement is monotonically increased, as the frontend gets more108bit count measurements. The frontend may reset it when a109channel/transponder is tuned.110 111Possible scales for this metric are:112 113- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the114 measurement was not complete yet.115 116- ``FE_SCALE_COUNTER`` - Number of error bits counted before the inner117 coding.118 119 120.. _DTV-STAT-PRE-TOTAL-BIT-COUNT:121 122DTV_STAT_PRE_TOTAL_BIT_COUNT123============================124 125Measures the amount of bits received before the inner code block, during126the same period as127:ref:`DTV_STAT_PRE_ERROR_BIT_COUNT <DTV-STAT-PRE-ERROR-BIT-COUNT>`128measurement was taken.129 130It should be noted that this measurement can be smaller than the total131amount of bits on the transport stream, as the frontend may need to132manually restart the measurement, losing some data between each133measurement interval.134 135This measurement is monotonically increased, as the frontend gets more136bit count measurements. The frontend may reset it when a137channel/transponder is tuned.138 139Possible scales for this metric are:140 141- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the142 measurement was not complete yet.143 144- ``FE_SCALE_COUNTER`` - Number of bits counted while measuring145 :ref:`DTV_STAT_PRE_ERROR_BIT_COUNT <DTV-STAT-PRE-ERROR-BIT-COUNT>`.146 147 148.. _DTV-STAT-POST-ERROR-BIT-COUNT:149 150DTV_STAT_POST_ERROR_BIT_COUNT151=============================152 153Measures the number of bit errors after the forward error correction154(FEC) done by inner code block (after Viterbi, LDPC or other inner155code).156 157This measure is taken during the same interval as158``DTV_STAT_POST_TOTAL_BIT_COUNT``.159 160In order to get the BER (Bit Error Rate) measurement, it should be161divided by162:ref:`DTV_STAT_POST_TOTAL_BIT_COUNT <DTV-STAT-POST-TOTAL-BIT-COUNT>`.163 164This measurement is monotonically increased, as the frontend gets more165bit count measurements. The frontend may reset it when a166channel/transponder is tuned.167 168Possible scales for this metric are:169 170- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the171 measurement was not complete yet.172 173- ``FE_SCALE_COUNTER`` - Number of error bits counted after the inner174 coding.175 176 177.. _DTV-STAT-POST-TOTAL-BIT-COUNT:178 179DTV_STAT_POST_TOTAL_BIT_COUNT180=============================181 182Measures the amount of bits received after the inner coding, during the183same period as184:ref:`DTV_STAT_POST_ERROR_BIT_COUNT <DTV-STAT-POST-ERROR-BIT-COUNT>`185measurement was taken.186 187It should be noted that this measurement can be smaller than the total188amount of bits on the transport stream, as the frontend may need to189manually restart the measurement, losing some data between each190measurement interval.191 192This measurement is monotonically increased, as the frontend gets more193bit count measurements. The frontend may reset it when a194channel/transponder is tuned.195 196Possible scales for this metric are:197 198- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the199 measurement was not complete yet.200 201- ``FE_SCALE_COUNTER`` - Number of bits counted while measuring202 :ref:`DTV_STAT_POST_ERROR_BIT_COUNT <DTV-STAT-POST-ERROR-BIT-COUNT>`.203 204 205.. _DTV-STAT-ERROR-BLOCK-COUNT:206 207DTV_STAT_ERROR_BLOCK_COUNT208==========================209 210Measures the number of block errors after the outer forward error211correction coding (after Reed-Solomon or other outer code).212 213This measurement is monotonically increased, as the frontend gets more214bit count measurements. The frontend may reset it when a215channel/transponder is tuned.216 217Possible scales for this metric are:218 219- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the220 measurement was not complete yet.221 222- ``FE_SCALE_COUNTER`` - Number of error blocks counted after the outer223 coding.224 225 226.. _DTV-STAT-TOTAL-BLOCK-COUNT:227 228DTV-STAT_TOTAL_BLOCK_COUNT229==========================230 231Measures the total number of blocks received during the same period as232:ref:`DTV_STAT_ERROR_BLOCK_COUNT <DTV-STAT-ERROR-BLOCK-COUNT>`233measurement was taken.234 235It can be used to calculate the PER indicator, by dividing236:ref:`DTV_STAT_ERROR_BLOCK_COUNT <DTV-STAT-ERROR-BLOCK-COUNT>` by237:ref:`DTV-STAT-TOTAL-BLOCK-COUNT`.238 239Possible scales for this metric are:240 241- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the242 measurement was not complete yet.243 244- ``FE_SCALE_COUNTER`` - Number of blocks counted while measuring245 :ref:`DTV_STAT_ERROR_BLOCK_COUNT <DTV-STAT-ERROR-BLOCK-COUNT>`.246