0001 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
0002 .. c:namespace:: DTV.fe
0003
0004 .. _FE_SET_TONE:
0005
0006 *****************
0007 ioctl FE_SET_TONE
0008 *****************
0009
0010 Name
0011 ====
0012
0013 FE_SET_TONE - Sets/resets the generation of the continuous 22kHz tone.
0014
0015 Synopsis
0016 ========
0017
0018 .. c:macro:: FE_SET_TONE
0019
0020 ``int ioctl(int fd, FE_SET_TONE, enum fe_sec_tone_mode tone)``
0021
0022 Arguments
0023 =========
0024
0025 ``fd``
0026 File descriptor returned by :c:func:`open()`.
0027
0028 ``tone``
0029 an integer enumered value described at :c:type:`fe_sec_tone_mode`
0030
0031 Description
0032 ===========
0033
0034 This ioctl is used to set the generation of the continuous 22kHz tone.
0035 This call requires read/write permissions.
0036
0037 Usually, satellite antenna subsystems require that the digital TV device
0038 to send a 22kHz tone in order to select between high/low band on some
0039 dual-band LNBf. It is also used to send signals to DiSEqC equipment, but
0040 this is done using the DiSEqC ioctls.
0041
0042 .. attention:: If more than one device is connected to the same antenna,
0043 setting a tone may interfere on other devices, as they may lose the
0044 capability of selecting the band. So, it is recommended that applications
0045 would change to SEC_TONE_OFF when the device is not used.
0046
0047 Return Value
0048 ============
0049
0050 On success 0 is returned.
0051
0052 On error -1 is returned, and the ``errno`` variable is set
0053 appropriately.
0054
0055 Generic error codes are described at the
0056 :ref:`Generic Error Codes <gen-errors>` chapter.
