1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2.. c:namespace:: DTV.fe
3
4.. _FE_SET_TONE:
5
6*****************
7ioctl FE_SET_TONE
8*****************
9
10Name
11====
12
13FE_SET_TONE - Sets/resets the generation of the continuous 22kHz tone.
14
15Synopsis
16========
17
18.. c:macro:: FE_SET_TONE
19
20``int ioctl(int fd, FE_SET_TONE, enum fe_sec_tone_mode tone)``
21
22Arguments
23=========
24
25``fd``
26    File descriptor returned by :c:func:`open()`.
27
28``tone``
29    an integer enumered value described at :c:type:`fe_sec_tone_mode`
30
31Description
32===========
33
34This ioctl is used to set the generation of the continuous 22kHz tone.
35This call requires read/write permissions.
36
37Usually, satellite antenna subsystems require that the digital TV device
38to send a 22kHz tone in order to select between high/low band on some
39dual-band LNBf. It is also used to send signals to DiSEqC equipment, but
40this is done using the DiSEqC ioctls.
41
42.. attention:: If more than one device is connected to the same antenna,
43   setting a tone may interfere on other devices, as they may lose the
44   capability of selecting the band. So, it is recommended that applications
45   would change to SEC_TONE_OFF when the device is not used.
46
47Return Value
48============
49
50On success 0 is returned.
51
52On error -1 is returned, and the ``errno`` variable is set
53appropriately.
54
55Generic error codes are described at the
56:ref:`Generic Error Codes <gen-errors>` chapter.
57