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+.. -*- coding: utf-8; mode: rst -*-
+
+.. _frontend-properties:
+
+DVB Frontend properties
+=======================
+
+Tuning into a Digital TV physical channel and starting decoding it
+requires changing a set of parameters, in order to control the tuner,
+the demodulator, the Linear Low-noise Amplifier (LNA) and to set the
+antenna subsystem via Satellite Equipment Control (SEC), on satellite
+systems. The actual parameters are specific to each particular digital
+TV standards, and may change as the digital TV specs evolves.
+
+In the past, the strategy used was to have a union with the parameters
+needed to tune for DVB-S, DVB-C, DVB-T and ATSC delivery systems grouped
+there. The problem is that, as the second generation standards appeared,
+those structs were not big enough to contain the additional parameters.
+Also, the union didn't have any space left to be expanded without
+breaking userspace. So, the decision was to deprecate the legacy
+union/struct based approach, in favor of a properties set approach.
+
+.. note:: On Linux DVB API version 3, setting a frontend were done via
+ :ref:`struct dvb_frontend_parameters <dvb-frontend-parameters>`.
+ This got replaced on version 5 (also called "S2API", as this API were
+ added originally_enabled to provide support for DVB-S2), because the
+ old API has a very limited support to new standards and new hardware.
+ This section describes the new and recommended way to set the frontend,
+ with suppports all digital TV delivery systems.
+
+Example: with the properties based approach, in order to set the tuner
+to a DVB-C channel at 651 kHz, modulated with 256-QAM, FEC 3/4 and
+symbol rate of 5.217 Mbauds, those properties should be sent to
+:ref:`FE_SET_PROPERTY <FE_GET_PROPERTY>` ioctl:
+
+- :ref:`DTV_DELIVERY_SYSTEM <DTV-DELIVERY-SYSTEM>` =
+ SYS_DVBC_ANNEX_A
+
+- :ref:`DTV_FREQUENCY <DTV-FREQUENCY>` = 651000000
+
+- :ref:`DTV_MODULATION <DTV-MODULATION>` = QAM_256
+
+- :ref:`DTV_INVERSION <DTV-INVERSION>` = INVERSION_AUTO
+
+- :ref:`DTV_SYMBOL_RATE <DTV-SYMBOL-RATE>` = 5217000
+
+- :ref:`DTV_INNER_FEC <DTV-INNER-FEC>` = FEC_3_4
+
+- :ref:`DTV_TUNE <DTV-TUNE>`
+
+The code that would that would do the above is show in
+:ref:`dtv-prop-example`.
+
+.. _dtv-prop-example:
+
+Example: Setting digital TV frontend properties
+===============================================
+
+.. code-block:: c
+
+ #include <stdio.h>
+ #include <fcntl.h>
+ #include <sys/ioctl.h>
+ #include <linux/dvb/frontend.h>
+
+ static struct dtv_property props[] = {
+ { .cmd = DTV_DELIVERY_SYSTEM, .u.data = SYS_DVBC_ANNEX_A },
+ { .cmd = DTV_FREQUENCY, .u.data = 651000000 },
+ { .cmd = DTV_MODULATION, .u.data = QAM_256 },
+ { .cmd = DTV_INVERSION, .u.data = INVERSION_AUTO },
+ { .cmd = DTV_SYMBOL_RATE, .u.data = 5217000 },
+ { .cmd = DTV_INNER_FEC, .u.data = FEC_3_4 },
+ { .cmd = DTV_TUNE }
+ };
+
+ static struct dtv_properties dtv_prop = {
+ .num = 6, .props = props
+ };
+
+ int main(void)
+ {
+ int fd = open("/dev/dvb/adapter0/frontend0", O_RDWR);
+
+ if (!fd) {
+ perror ("open");
+ return -1;
+ }
+ if (ioctl(fd, FE_SET_PROPERTY, &dtv_prop) == -1) {
+ perror("ioctl");
+ return -1;
+ }
+ printf("Frontend set\\n");
+ return 0;
+ }
+
+.. attention:: While it is possible to directly call the Kernel code like the
+ above example, it is strongly recommended to use
+ `libdvbv5 <https://linuxtv.org/docs/libdvbv5/index.html>`__, as it
+ provides abstraction to work with the supported digital TV standards and
+ provides methods for usual operations like program scanning and to
+ read/write channel descriptor files.
+
+
+.. toctree::
+ :maxdepth: 1
+
+ dtv-stats
+ dtv-fe-stats
+ dtv-property
+ dtv-properties
+ dvbproperty-006
+ fe_property_parameters
+ frontend-stat-properties
+ frontend-property-terrestrial-systems
+ frontend-property-cable-systems
+ frontend-property-satellite-systems