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.. -*- coding: utf-8; mode: rst -*-
FE_SET_TONE - Sets/resets the generation of the continuous 22kHz tone.
.. c:function:: int ioctl( int fd, FE_SET_TONE, enum fe_sec_tone_mode tone )
:name: FE_SET_TONE
File descriptor returned by :ref:`open() <frontend_f_open>`.
an integer enumered value described at :c:type:`fe_sec_tone_mode`
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
Generic error codes are described at the
:ref:`Generic Error Codes <gen-errors>` chapter.