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media: fe_property_parameters.rst: better document bandwidth
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Use a table to document the supported bandwidths. That makes
it clearer to readers.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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Mauro Carvalho Chehab committed Sep 5, 2017
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38 changes: 23 additions & 15 deletions Documentation/media/uapi/dvb/fe_property_parameters.rst
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Expand Up @@ -116,29 +116,37 @@ Should be set only for terrestrial delivery systems.
Possible values: ``1712000``, ``5000000``, ``6000000``, ``7000000``,
``8000000``, ``10000000``.

.. note::
======================= =======================================================
Terrestrial Standard Possible values for bandwidth
======================= =======================================================
ATSC (version 1) No need to set. It is always 6MHz.
DMTB No need to set. It is always 8MHz.
DVB-T 6MHz, 7MHz and 8MHz.
DVB-T2 1.172 MHz, 5MHz, 6MHz, 7MHz, 8MHz and 10MHz
ISDB-T 5MHz, 6MHz, 7MHz and 8MHz, although most places
use 6MHz.
======================= =======================================================

#. DVB-T supports 6, 7 and 8MHz.

#. DVB-T2 supports 1.172, 5, 6, 7, 8 and 10MHz.
.. note::

#. ISDB-T supports 5MHz, 6MHz, 7MHz and 8MHz, although most
places use 6MHz.

#. On DVB-C and DVB-S/S2, the bandwidth depends on the symbol rate.
So, the Kernel will silently ignore setting :ref:`DTV-BANDWIDTH-HZ`.
#. For ISDB-Tsb, the bandwidth can vary depending on the number of
connected segments.

#. For DVB-C and DVB-S/S2, the Kernel will return an estimation of the
bandwidth, calculated from :ref:`DTV-SYMBOL-RATE` and from
the rolloff, with is fixed for DVB-C and DVB-S.
It can be easily derived from other parameters
(DTV_ISDBT_SB_SEGMENT_IDX, DTV_ISDBT_SB_SEGMENT_COUNT).

#. For DVB-S2, the bandwidth estimation will use :ref:`DTV-ROLLOFF`.
#. On Satellite and Cable delivery systems, the bandwidth depends on
the symbol rate. So, the Kernel will silently ignore any setting
:ref:`DTV-BANDWIDTH-HZ`. I will however fill it back with a
bandwidth estimation.

#. For ISDB-Tsb, it can vary depending on the number of connected
segments.
Such bandwidth estimation takes into account the symbol rate set with
:ref:`DTV-SYMBOL-RATE`, and the rolloff factor, with is fixed for
DVB-C and DVB-S.

#. Bandwidth in ISDB-Tsb can be easily derived from other parameters
(DTV_ISDBT_SB_SEGMENT_IDX, DTV_ISDBT_SB_SEGMENT_COUNT).
For DVB-S2, the rolloff should also be set via :ref:`DTV-ROLLOFF`.


.. _DTV-INVERSION:
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