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media: fe_property_parameters.rst: better document bandwidth 

Use a table to document the supported bandwidths. That makes
it clearer to readers.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
hifive-unleashed-5.1
Mauro Carvalho Chehab 2017-08-31 07:17:21 -04:00
parent 1181415dc6
commit 7d661edd0d
1 changed files with 26 additions and 18 deletions
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44
Documentation/media/uapi/dvb/fe_property_parameters.rst
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@ -116,30 +116,38 @@ Should be set only for terrestrial delivery systems.
Possible values: ``1712000``, ``5000000``, ``6000000``, ``7000000``,
``8000000``, ``10000000``.
======================= =======================================================
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.
======================= =======================================================
.. note::
#. DVB-T supports 6, 7 and 8MHz.
#. DVB-T2 supports 1.172, 5, 6, 7, 8 and 10MHz.
#. For ISDB-Tsb, the bandwidth can vary depending on the number of
connected segments.
#. 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 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.
#. For DVB-S2, the bandwidth estimation will use :ref:`DTV-ROLLOFF`.
#. For ISDB-Tsb, it can vary depending on the number of connected
segments.
#. Bandwidth in ISDB-Tsb can be easily derived from other parameters
It can be easily derived from other parameters
(DTV_ISDBT_SB_SEGMENT_IDX, DTV_ISDBT_SB_SEGMENT_COUNT).
#. 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.
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.
For DVB-S2, the rolloff should also be set via :ref:`DTV-ROLLOFF`.
.. _DTV-INVERSION: