Commit fed7b888 authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab
Browse files

[media] doc-rst: improve DTV_BANDWIDTH_HZ notes 



There are several notes for this DTV property. Some are
outdated, so take some care of it, making it updated.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent 5632442d

Documentation/media/uapi/dvb/fe_property_parameters.rst

+17 −11
Original line number Diff line number Diff line
@@ -219,23 +219,29 @@ Bandwidth for the channel, in HZ. 
Possible values: ``1712000``, ``5000000``, ``6000000``, ``7000000``,

``8000000``, ``10000000``.



Notes:

.. note::



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



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



1) For ISDB-T it should be always 6000000Hz (6MHz)

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

     places use 6MHz.



2) For ISDB-Tsb it can vary depending on the number of connected

segments

  #. 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`.



3) Bandwidth doesn't apply for DVB-C transmissions, as the bandwidth for

DVB-C depends on the symbol rate

  #. 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.



4) Bandwidth in ISDB-T is fixed (6MHz) or 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`.



5) DVB-T supports 6, 7 and 8MHz.

  #. For ISDB-Tsb, it can vary depending on the number of connected

     segments.



6) In addition, DVB-T2 supports 1.172, 5 and 10MHz.

  #. Bandwidth in ISDB-Tsb can be easily derived from other parameters

     (DTV_ISDBT_SB_SEGMENT_IDX, DTV_ISDBT_SB_SEGMENT_COUNT).





.. _DTV-INVERSION: