Documentation/userspace-api/media/dvb/fe_property_parameters.rst

Source file repositories/reference/linux-study-clean/Documentation/userspace-api/media/dvb/fe_property_parameters.rst

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Documentation/userspace-api/media/dvb/fe_property_parameters.rst
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Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

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.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later

.. _fe_property_parameters:

******************************
Digital TV property parameters
******************************

There are several different Digital TV parameters that can be used by
:ref:`FE_SET_PROPERTY and FE_GET_PROPERTY ioctls<FE_GET_PROPERTY>`.
This section describes each of them. Please notice, however, that only
a subset of them are needed to setup a frontend.


.. _DTV-UNDEFINED:

DTV_UNDEFINED
=============

Used internally. A GET/SET operation for it won't change or return
anything.


.. _DTV-TUNE:

DTV_TUNE
========

Interpret the cache of data, build either a traditional frontend
tunerequest so we can pass validation in the ``FE_SET_FRONTEND`` ioctl.


.. _DTV-CLEAR:

DTV_CLEAR
=========

Reset a cache of data specific to the frontend here. This does not
effect hardware.


.. _DTV-FREQUENCY:

DTV_FREQUENCY
=============

Frequency of the digital TV transponder/channel.

.. note::

  #. For satellite delivery systems, the frequency is in kHz.

  #. For cable and terrestrial delivery systems, the frequency is in
     Hz.

  #. On most delivery systems, the frequency is the center frequency
     of the transponder/channel. The exception is for ISDB-T, where
     the main carrier has a 1/7 offset from the center.

  #. For ISDB-T, the channels are usually transmitted with an offset of
     about 143kHz. E.g. a valid frequency could be 474,143 kHz. The
     stepping is  bound to the bandwidth of the channel which is
     typically 6MHz.

  #. In ISDB-Tsb, the channel consists of only one or three segments the
     frequency step is 429kHz, 3*429 respectively.


.. _DTV-MODULATION:

Annotation

Implementation Notes