1 .. SPDX-License-Identifier: GFDL-1.1-no-invari
2
3 .. _sdr:
4
5 **************************************
6 Software Defined Radio Interface (SDR)
7 **************************************
8
9 SDR is an abbreviation of Software Defined Rad
10 uses application software for modulation or de
11 is intended for controlling and data streaming
12
13 SDR devices are accessed through character dev
14 ``/dev/swradio0`` to ``/dev/swradio255`` with
15 dynamically allocated minor numbers 0 to 255.
16
17
18 Querying Capabilities
19 =====================
20
21 Devices supporting the SDR receiver interface
22 ``V4L2_CAP_SDR_CAPTURE`` and ``V4L2_CAP_TUNER`
23 ``capabilities`` field of struct
24 :c:type:`v4l2_capability` returned by the
25 :ref:`VIDIOC_QUERYCAP` ioctl. That flag means
26 device has an Analog to Digital Converter (ADC
27 element for the SDR receiver.
28
29 Devices supporting the SDR transmitter interfa
30 ``V4L2_CAP_SDR_OUTPUT`` and ``V4L2_CAP_MODULAT
31 ``capabilities`` field of struct
32 :c:type:`v4l2_capability` returned by the
33 :ref:`VIDIOC_QUERYCAP` ioctl. That flag means
34 device has an Digital to Analog Converter (DAC
35 element for the SDR transmitter.
36
37 At least one of the read/write or streaming I/
38 must be supported.
39
40
41 Supplemental Functions
42 ======================
43
44 SDR devices can support :ref:`controls <contro
45 the :ref:`tuner` ioctls. Tuner ioctls are used
46 ADC/DAC sampling rate (sampling frequency) and
47 frequency (RF).
48
49 The ``V4L2_TUNER_SDR`` tuner type is used for
50 frequency, and the ``V4L2_TUNER_RF`` tuner typ
51 radio frequency. The tuner index of the RF tun
52 follow the SDR tuner index. Normally the SDR t
53 tuner is #1.
54
55 The :ref:`VIDIOC_S_HW_FREQ_SEEK` ioctl is
56 not supported.
57
58
59 Data Format Negotiation
60 =======================
61
62 The SDR device uses the :ref:`format` ioctls t
63 capture and output format. Both the sampling r
64 streaming format are bound to that selectable
65 basic :ref:`format` ioctls, the
66 :ref:`VIDIOC_ENUM_FMT` ioctl must be supported
67 well.
68
69 To use the :ref:`format` ioctls applications s
70 field of a struct :c:type:`v4l2_format` to
71 ``V4L2_BUF_TYPE_SDR_CAPTURE`` or ``V4L2_BUF_TY
72 the struct :c:type:`v4l2_sdr_format` ``sdr`` m
73 of the ``fmt`` union as needed per the desired
74 there are two fields, ``pixelformat`` and ``bu
75 struct :c:type:`v4l2_sdr_format` which are use
76 Content of the ``pixelformat`` is V4L2 FourCC
77 The ``buffersize`` field is maximum buffer siz
78 data transfer, set by the driver in order to i
79
80
81 .. c:type:: v4l2_sdr_format
82
83 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm
84
85 .. flat-table:: struct v4l2_sdr_format
86 :header-rows: 0
87 :stub-columns: 0
88 :widths: 1 1 2
89
90 * - __u32
91 - ``pixelformat``
92 - The data format or type of compression
93 This is a little endian
94 :ref:`four character code <v4l2-fourcc
95 formats in :ref:`sdr-formats`.
96 * - __u32
97 - ``buffersize``
98 - Maximum size in bytes required for dat
99 driver.
100 * - __u8
101 - ``reserved[24]``
102 - This array is reserved for future exte
103 applications must set it to zero.
104
105
106 An SDR device may support :ref:`read/write <rw
107 (:ref:`memory mapping <mmap>` or :ref:`user po
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