frontend-stat-properties.rst (7856B)
1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2 3.. _frontend-stat-properties: 4 5****************************** 6Frontend statistics indicators 7****************************** 8 9The values are returned via ``dtv_property.stat``. If the property is 10supported, ``dtv_property.stat.len`` is bigger than zero. 11 12For most delivery systems, ``dtv_property.stat.len`` will be 1 if the 13stats is supported, and the properties will return a single value for 14each parameter. 15 16It should be noted, however, that new OFDM delivery systems like ISDB 17can use different modulation types for each group of carriers. On such 18standards, up to 3 groups of statistics can be provided, and 19``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 first 23value at :c:type:`dtv_property.stat.dtv_stats <dtv_stats>` array refers 24to the global metric. The other elements of the array represent each 25layer, 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 on 30two elements: 31 32- ``svalue`` or ``uvalue``, where ``svalue`` is for signed values of 33 the measure (dB measures) and ``uvalue`` is for unsigned values 34 (counters, relative scale) 35 36- ``scale`` - Scale for the value. It can be: 37 38 - ``FE_SCALE_NOT_AVAILABLE`` - The parameter is supported by the 39 frontend, but it was not possible to collect it (could be a 40 transitory or permanent condition) 41 42 - ``FE_SCALE_DECIBEL`` - parameter is a signed value, measured in 43 1/1000 dB 44 45 - ``FE_SCALE_RELATIVE`` - parameter is a unsigned value, where 0 46 means 0% and 65535 means 100%. 47 48 - ``FE_SCALE_COUNTER`` - parameter is a unsigned value that counts 49 the occurrence of an event, like bit error, block error, or lapsed 50 time. 51 52 53.. _DTV-STAT-SIGNAL-STRENGTH: 54 55DTV_STAT_SIGNAL_STRENGTH 56======================== 57 58Indicates the signal strength level at the analog part of the tuner or 59of the demod. 60 61Possible scales for this metric are: 62 63- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the 64 measurement was not complete yet. 65 66- ``FE_SCALE_DECIBEL`` - signal strength is in 0.001 dBm units, power 67 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_CNR 76============ 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 the 83 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_COUNT 94============================ 95 96Measures the number of bit errors before the forward error correction 97(FEC) on the inner coding block (before Viterbi, LDPC or other inner 98code). 99 100This measure is taken during the same interval as 101``DTV_STAT_PRE_TOTAL_BIT_COUNT``. 102 103In order to get the BER (Bit Error Rate) measurement, it should be 104divided by 105:ref:`DTV_STAT_PRE_TOTAL_BIT_COUNT <DTV-STAT-PRE-TOTAL-BIT-COUNT>`. 106 107This measurement is monotonically increased, as the frontend gets more 108bit count measurements. The frontend may reset it when a 109channel/transponder is tuned. 110 111Possible scales for this metric are: 112 113- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the 114 measurement was not complete yet. 115 116- ``FE_SCALE_COUNTER`` - Number of error bits counted before the inner 117 coding. 118 119 120.. _DTV-STAT-PRE-TOTAL-BIT-COUNT: 121 122DTV_STAT_PRE_TOTAL_BIT_COUNT 123============================ 124 125Measures the amount of bits received before the inner code block, during 126the same period as 127: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 total 131amount of bits on the transport stream, as the frontend may need to 132manually restart the measurement, losing some data between each 133measurement interval. 134 135This measurement is monotonically increased, as the frontend gets more 136bit count measurements. The frontend may reset it when a 137channel/transponder is tuned. 138 139Possible scales for this metric are: 140 141- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the 142 measurement was not complete yet. 143 144- ``FE_SCALE_COUNTER`` - Number of bits counted while measuring 145 :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_COUNT 151============================= 152 153Measures the number of bit errors after the forward error correction 154(FEC) done by inner code block (after Viterbi, LDPC or other inner 155code). 156 157This measure is taken during the same interval as 158``DTV_STAT_POST_TOTAL_BIT_COUNT``. 159 160In order to get the BER (Bit Error Rate) measurement, it should be 161divided by 162:ref:`DTV_STAT_POST_TOTAL_BIT_COUNT <DTV-STAT-POST-TOTAL-BIT-COUNT>`. 163 164This measurement is monotonically increased, as the frontend gets more 165bit count measurements. The frontend may reset it when a 166channel/transponder is tuned. 167 168Possible scales for this metric are: 169 170- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the 171 measurement was not complete yet. 172 173- ``FE_SCALE_COUNTER`` - Number of error bits counted after the inner 174 coding. 175 176 177.. _DTV-STAT-POST-TOTAL-BIT-COUNT: 178 179DTV_STAT_POST_TOTAL_BIT_COUNT 180============================= 181 182Measures the amount of bits received after the inner coding, during the 183same period as 184: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 total 188amount of bits on the transport stream, as the frontend may need to 189manually restart the measurement, losing some data between each 190measurement interval. 191 192This measurement is monotonically increased, as the frontend gets more 193bit count measurements. The frontend may reset it when a 194channel/transponder is tuned. 195 196Possible scales for this metric are: 197 198- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the 199 measurement was not complete yet. 200 201- ``FE_SCALE_COUNTER`` - Number of bits counted while measuring 202 :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_COUNT 208========================== 209 210Measures the number of block errors after the outer forward error 211correction coding (after Reed-Solomon or other outer code). 212 213This measurement is monotonically increased, as the frontend gets more 214bit count measurements. The frontend may reset it when a 215channel/transponder is tuned. 216 217Possible scales for this metric are: 218 219- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the 220 measurement was not complete yet. 221 222- ``FE_SCALE_COUNTER`` - Number of error blocks counted after the outer 223 coding. 224 225 226.. _DTV-STAT-TOTAL-BLOCK-COUNT: 227 228DTV-STAT_TOTAL_BLOCK_COUNT 229========================== 230 231Measures the total number of blocks received during the same period as 232: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 dividing 236:ref:`DTV_STAT_ERROR_BLOCK_COUNT <DTV-STAT-ERROR-BLOCK-COUNT>` by 237: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 the 242 measurement was not complete yet. 243 244- ``FE_SCALE_COUNTER`` - Number of blocks counted while measuring 245 :ref:`DTV_STAT_ERROR_BLOCK_COUNT <DTV-STAT-ERROR-BLOCK-COUNT>`.