1 .. SPDX-License-Identifier: GFDL-1.1-no-invari
2
3 .. _fm-tx-controls:
4
5 ********************************
6 FM Transmitter Control Reference
7 ********************************
8
9 The FM Transmitter (FM_TX) class includes cont
10 of FM transmissions capable devices. Currently
11 parameters for audio compression, pilot tone g
12 limiter, RDS transmission and tuning power fea
13
14
15 .. _fm-tx-control-id:
16
17 FM_TX Control IDs
18 =================
19
20 ``V4L2_CID_FM_TX_CLASS (class)``
21 The FM_TX class descriptor. Calling
22 :ref:`VIDIOC_QUERYCTRL` for this control w
23 return a description of this control class
24
25 ``V4L2_CID_RDS_TX_DEVIATION (integer)``
26 Configures RDS signal frequency deviation
27 step are driver-specific.
28
29 ``V4L2_CID_RDS_TX_PI (integer)``
30 Sets the RDS Programme Identification fiel
31
32 ``V4L2_CID_RDS_TX_PTY (integer)``
33 Sets the RDS Programme Type field for tran
34 to 31 pre-defined programme types.
35
36 ``V4L2_CID_RDS_TX_PS_NAME (string)``
37 Sets the Programme Service name (PS_NAME)
38 intended for static display on a receiver.
39 listeners in programme service identificat
40 Annex E of :ref:`iec62106`, the RDS specif
41 description of the correct character encod
42 name strings. Also from RDS specification,
43 eight character text. However, it is also
44 which can scroll strings sized as 8 x N ch
45 must be configured with steps of 8 charact
46 always contain a string with size multiple
47
48 ``V4L2_CID_RDS_TX_RADIO_TEXT (string)``
49 Sets the Radio Text info for transmission.
50 description of what is being broadcasted.
51 applied when broadcaster wishes to transmi
52 programme-related information or any other
53 RadioText should be used in addition to ``
54 The encoding for Radio Text strings is als
55 E of :ref:`iec62106`. The length of Radio
56 which RDS Block is being used to transmit
57 or 64 (2B block). However, it is also poss
58 which can scroll strings sized as 32 x N o
59 this control must be configured with steps
60 The result is it must always contain a str
61 32 or 64.
62
63 ``V4L2_CID_RDS_TX_MONO_STEREO (boolean)``
64 Sets the Mono/Stereo bit of the Decoder Id
65 then the audio was recorded as stereo.
66
67 ``V4L2_CID_RDS_TX_ARTIFICIAL_HEAD (boolean)``
68 Sets the
69 `Artificial Head <http://en.wikipedia.org/
70 bit of the Decoder Identification code. If
71 recorded using an artificial head.
72
73 ``V4L2_CID_RDS_TX_COMPRESSED (boolean)``
74 Sets the Compressed bit of the Decoder Ide
75 then the audio is compressed.
76
77 ``V4L2_CID_RDS_TX_DYNAMIC_PTY (boolean)``
78 Sets the Dynamic PTY bit of the Decoder Id
79 then the PTY code is dynamically switched.
80
81 ``V4L2_CID_RDS_TX_TRAFFIC_ANNOUNCEMENT (boolea
82 If set, then a traffic announcement is in
83
84 ``V4L2_CID_RDS_TX_TRAFFIC_PROGRAM (boolean)``
85 If set, then the tuned programme carries t
86
87 ``V4L2_CID_RDS_TX_MUSIC_SPEECH (boolean)``
88 If set, then this channel broadcasts music
89 broadcasts speech. If the transmitter does
90 then it should be set.
91
92 ``V4L2_CID_RDS_TX_ALT_FREQS_ENABLE (boolean)``
93 If set, then transmit alternate frequencie
94
95 ``V4L2_CID_RDS_TX_ALT_FREQS (__u32 array)``
96 The alternate frequencies in kHz units. Th
97 up to 25 frequencies to be defined. Driver
98 frequencies so check the array size.
99
100 ``V4L2_CID_AUDIO_LIMITER_ENABLED (boolean)``
101 Enables or disables the audio deviation li
102 is useful when trying to maximize the audi
103 receiver-generated distortion and prevent
104
105 ``V4L2_CID_AUDIO_LIMITER_RELEASE_TIME (integer
106 Sets the audio deviation limiter feature r
107 useconds. Step and range are driver-specif
108
109 ``V4L2_CID_AUDIO_LIMITER_DEVIATION (integer)``
110 Configures audio frequency deviation level
111 are driver-specific.
112
113 ``V4L2_CID_AUDIO_COMPRESSION_ENABLED (boolean)
114 Enables or disables the audio compression
115 amplifies signals below the threshold by a
116 audio signals above the threshold by the r
117 Threshold).
118
119 ``V4L2_CID_AUDIO_COMPRESSION_GAIN (integer)``
120 Sets the gain for audio compression featur
121 range and step are driver-specific.
122
123 ``V4L2_CID_AUDIO_COMPRESSION_THRESHOLD (intege
124 Sets the threshold level for audio compres
125 value. The range and step are driver-speci
126
127 ``V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME (inte
128 Sets the attack time for audio compression
129 value. The range and step are driver-speci
130
131 ``V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME (int
132 Sets the release time for audio compressio
133 useconds value. The range and step are dri
134
135 ``V4L2_CID_PILOT_TONE_ENABLED (boolean)``
136 Enables or disables the pilot tone generat
137
138 ``V4L2_CID_PILOT_TONE_DEVIATION (integer)``
139 Configures pilot tone frequency deviation
140 range and step are driver-specific.
141
142 ``V4L2_CID_PILOT_TONE_FREQUENCY (integer)``
143 Configures pilot tone frequency value. Uni
144 step are driver-specific.
145
146 ``V4L2_CID_TUNE_PREEMPHASIS``
147 (enum)
148
149 enum v4l2_preemphasis -
150 Configures the pre-emphasis value for broa
151 filter is applied to the broadcast to acce
152 frequencies. Depending on the region, a ti
153 or 75 useconds is used. The enum v4l2_pree
154 values for pre-emphasis. Here they are:
155
156
157
158 .. flat-table::
159 :header-rows: 0
160 :stub-columns: 0
161
162 * - ``V4L2_PREEMPHASIS_DISABLED``
163 - No pre-emphasis is applied.
164 * - ``V4L2_PREEMPHASIS_50_uS``
165 - A pre-emphasis of 50 uS is used.
166 * - ``V4L2_PREEMPHASIS_75_uS``
167 - A pre-emphasis of 75 uS is used.
168
169
170
171 ``V4L2_CID_TUNE_POWER_LEVEL (integer)``
172 Sets the output power level for signal tra
173 dBuV. Range and step are driver-specific.
174
175 ``V4L2_CID_TUNE_ANTENNA_CAPACITOR (integer)``
176 This selects the value of antenna tuning c
177 automatically if set to zero. Unit, range
178 driver-specific.
179
180 For more details about RDS specification, refe
181 document, from CENELEC.
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