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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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