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.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
.. c:namespace:: DTV.fe
.. _FE_SET_TONE:
*****************
ioctl FE_SET_TONE
*****************
Name
====
FE_SET_TONE - Sets/resets the generation of the continuous 22kHz tone.
Synopsis
========
.. c:macro:: FE_SET_TONE
``int ioctl(int fd, FE_SET_TONE, enum fe_sec_tone_mode tone)``
Arguments
=========
``fd``
File descriptor returned by :c:func:`open()`.
``tone``
an integer enumered value described at :c:type:`fe_sec_tone_mode`
Description
===========
This ioctl is used to set the generation of the continuous 22kHz tone.
This call requires read/write permissions.
Usually, satellite antenna subsystems require that the digital TV device
to send a 22kHz tone in order to select between high/low band on some
dual-band LNBf. It is also used to send signals to DiSEqC equipment, but
this is done using the DiSEqC ioctls.
.. attention:: If more than one device is connected to the same antenna,
setting a tone may interfere on other devices, as they may lose the
capability of selecting the band. So, it is recommended that applications
would change to SEC_TONE_OFF when the device is not used.
Return Value
============
On success 0 is returned.
On error -1 is returned, and the ``errno`` variable is set
appropriately.
Generic error codes are described at the
:ref:`Generic Error Codes <gen-errors>` chapter.
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