| .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later |
| |
| .. _frontend-stat-properties: |
| |
| ****************************** |
| Frontend statistics indicators |
| ****************************** |
| |
| The values are returned via ``dtv_property.stat``. If the property is |
| supported, ``dtv_property.stat.len`` is bigger than zero. |
| |
| For most delivery systems, ``dtv_property.stat.len`` will be 1 if the |
| stats is supported, and the properties will return a single value for |
| each parameter. |
| |
| It should be noted, however, that new OFDM delivery systems like ISDB |
| can use different modulation types for each group of carriers. On such |
| standards, up to 3 groups of statistics can be provided, and |
| ``dtv_property.stat.len`` is updated to reflect the "global" metrics, |
| plus one metric per each carrier group (called "layer" on ISDB). |
| |
| So, in order to be consistent with other delivery systems, the first |
| value at :c:type:`dtv_property.stat.dtv_stats <dtv_stats>` array refers |
| to the global metric. The other elements of the array represent each |
| layer, starting from layer A(index 1), layer B (index 2) and so on. |
| |
| The number of filled elements are stored at ``dtv_property.stat.len``. |
| |
| Each element of the ``dtv_property.stat.dtv_stats`` array consists on |
| two elements: |
| |
| - ``svalue`` or ``uvalue``, where ``svalue`` is for signed values of |
| the measure (dB measures) and ``uvalue`` is for unsigned values |
| (counters, relative scale) |
| |
| - ``scale`` - Scale for the value. It can be: |
| |
| - ``FE_SCALE_NOT_AVAILABLE`` - The parameter is supported by the |
| frontend, but it was not possible to collect it (could be a |
| transitory or permanent condition) |
| |
| - ``FE_SCALE_DECIBEL`` - parameter is a signed value, measured in |
| 1/1000 dB |
| |
| - ``FE_SCALE_RELATIVE`` - parameter is a unsigned value, where 0 |
| means 0% and 65535 means 100%. |
| |
| - ``FE_SCALE_COUNTER`` - parameter is a unsigned value that counts |
| the occurrence of an event, like bit error, block error, or lapsed |
| time. |
| |
| |
| .. _DTV-STAT-SIGNAL-STRENGTH: |
| |
| DTV_STAT_SIGNAL_STRENGTH |
| ======================== |
| |
| Indicates the signal strength level at the analog part of the tuner or |
| of the demod. |
| |
| Possible scales for this metric are: |
| |
| - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the |
| measurement was not complete yet. |
| |
| - ``FE_SCALE_DECIBEL`` - signal strength is in 0.001 dBm units, power |
| measured in miliwatts. This value is generally negative. |
| |
| - ``FE_SCALE_RELATIVE`` - The frontend provides a 0% to 100% |
| measurement for power (actually, 0 to 65535). |
| |
| |
| .. _DTV-STAT-CNR: |
| |
| DTV_STAT_CNR |
| ============ |
| |
| Indicates the Signal to Noise ratio for the main carrier. |
| |
| Possible scales for this metric are: |
| |
| - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the |
| measurement was not complete yet. |
| |
| - ``FE_SCALE_DECIBEL`` - Signal/Noise ratio is in 0.001 dB units. |
| |
| - ``FE_SCALE_RELATIVE`` - The frontend provides a 0% to 100% |
| measurement for Signal/Noise (actually, 0 to 65535). |
| |
| |
| .. _DTV-STAT-PRE-ERROR-BIT-COUNT: |
| |
| DTV_STAT_PRE_ERROR_BIT_COUNT |
| ============================ |
| |
| Measures the number of bit errors before the forward error correction |
| (FEC) on the inner coding block (before Viterbi, LDPC or other inner |
| code). |
| |
| This measure is taken during the same interval as |
| ``DTV_STAT_PRE_TOTAL_BIT_COUNT``. |
| |
| In order to get the BER (Bit Error Rate) measurement, it should be |
| divided by |
| :ref:`DTV_STAT_PRE_TOTAL_BIT_COUNT <DTV-STAT-PRE-TOTAL-BIT-COUNT>`. |
| |
| This measurement is monotonically increased, as the frontend gets more |
| bit count measurements. The frontend may reset it when a |
| channel/transponder is tuned. |
| |
| Possible scales for this metric are: |
| |
| - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the |
| measurement was not complete yet. |
| |
| - ``FE_SCALE_COUNTER`` - Number of error bits counted before the inner |
| coding. |
| |
| |
| .. _DTV-STAT-PRE-TOTAL-BIT-COUNT: |
| |
| DTV_STAT_PRE_TOTAL_BIT_COUNT |
| ============================ |
| |
| Measures the amount of bits received before the inner code block, during |
| the same period as |
| :ref:`DTV_STAT_PRE_ERROR_BIT_COUNT <DTV-STAT-PRE-ERROR-BIT-COUNT>` |
| measurement was taken. |
| |
| It should be noted that this measurement can be smaller than the total |
| amount of bits on the transport stream, as the frontend may need to |
| manually restart the measurement, losing some data between each |
| measurement interval. |
| |
| This measurement is monotonically increased, as the frontend gets more |
| bit count measurements. The frontend may reset it when a |
| channel/transponder is tuned. |
| |
| Possible scales for this metric are: |
| |
| - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the |
| measurement was not complete yet. |
| |
| - ``FE_SCALE_COUNTER`` - Number of bits counted while measuring |
| :ref:`DTV_STAT_PRE_ERROR_BIT_COUNT <DTV-STAT-PRE-ERROR-BIT-COUNT>`. |
| |
| |
| .. _DTV-STAT-POST-ERROR-BIT-COUNT: |
| |
| DTV_STAT_POST_ERROR_BIT_COUNT |
| ============================= |
| |
| Measures the number of bit errors after the forward error correction |
| (FEC) done by inner code block (after Viterbi, LDPC or other inner |
| code). |
| |
| This measure is taken during the same interval as |
| ``DTV_STAT_POST_TOTAL_BIT_COUNT``. |
| |
| In order to get the BER (Bit Error Rate) measurement, it should be |
| divided by |
| :ref:`DTV_STAT_POST_TOTAL_BIT_COUNT <DTV-STAT-POST-TOTAL-BIT-COUNT>`. |
| |
| This measurement is monotonically increased, as the frontend gets more |
| bit count measurements. The frontend may reset it when a |
| channel/transponder is tuned. |
| |
| Possible scales for this metric are: |
| |
| - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the |
| measurement was not complete yet. |
| |
| - ``FE_SCALE_COUNTER`` - Number of error bits counted after the inner |
| coding. |
| |
| |
| .. _DTV-STAT-POST-TOTAL-BIT-COUNT: |
| |
| DTV_STAT_POST_TOTAL_BIT_COUNT |
| ============================= |
| |
| Measures the amount of bits received after the inner coding, during the |
| same period as |
| :ref:`DTV_STAT_POST_ERROR_BIT_COUNT <DTV-STAT-POST-ERROR-BIT-COUNT>` |
| measurement was taken. |
| |
| It should be noted that this measurement can be smaller than the total |
| amount of bits on the transport stream, as the frontend may need to |
| manually restart the measurement, losing some data between each |
| measurement interval. |
| |
| This measurement is monotonically increased, as the frontend gets more |
| bit count measurements. The frontend may reset it when a |
| channel/transponder is tuned. |
| |
| Possible scales for this metric are: |
| |
| - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the |
| measurement was not complete yet. |
| |
| - ``FE_SCALE_COUNTER`` - Number of bits counted while measuring |
| :ref:`DTV_STAT_POST_ERROR_BIT_COUNT <DTV-STAT-POST-ERROR-BIT-COUNT>`. |
| |
| |
| .. _DTV-STAT-ERROR-BLOCK-COUNT: |
| |
| DTV_STAT_ERROR_BLOCK_COUNT |
| ========================== |
| |
| Measures the number of block errors after the outer forward error |
| correction coding (after Reed-Solomon or other outer code). |
| |
| This measurement is monotonically increased, as the frontend gets more |
| bit count measurements. The frontend may reset it when a |
| channel/transponder is tuned. |
| |
| Possible scales for this metric are: |
| |
| - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the |
| measurement was not complete yet. |
| |
| - ``FE_SCALE_COUNTER`` - Number of error blocks counted after the outer |
| coding. |
| |
| |
| .. _DTV-STAT-TOTAL-BLOCK-COUNT: |
| |
| DTV-STAT_TOTAL_BLOCK_COUNT |
| ========================== |
| |
| Measures the total number of blocks received during the same period as |
| :ref:`DTV_STAT_ERROR_BLOCK_COUNT <DTV-STAT-ERROR-BLOCK-COUNT>` |
| measurement was taken. |
| |
| It can be used to calculate the PER indicator, by dividing |
| :ref:`DTV_STAT_ERROR_BLOCK_COUNT <DTV-STAT-ERROR-BLOCK-COUNT>` by |
| :ref:`DTV-STAT-TOTAL-BLOCK-COUNT`. |
| |
| Possible scales for this metric are: |
| |
| - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the |
| measurement was not complete yet. |
| |
| - ``FE_SCALE_COUNTER`` - Number of blocks counted while measuring |
| :ref:`DTV_STAT_ERROR_BLOCK_COUNT <DTV-STAT-ERROR-BLOCK-COUNT>`. |
