+<section id="frontend-properties">
+<title>DVB Frontend properties</title>
+<para>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.</para>
+<para>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.</para>
+
+<para>NOTE: on Linux DVB API version 3, setting a frontend were done via
+ <link linkend="dvb-frontend-parameters">struct <constant>dvb_frontend_parameters</constant></link>.
+ 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.</para>
+
+<para>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
+ <link linkend="FE_GET_PROPERTY"><constant>FE_SET_PROPERTY</constant></link> ioctl:</para>
+ <itemizedlist>
+ <listitem><para>&DTV-DELIVERY-SYSTEM; = SYS_DVBC_ANNEX_A</para></listitem>
+ <listitem><para>&DTV-FREQUENCY; = 651000000</para></listitem>
+ <listitem><para>&DTV-MODULATION; = QAM_256</para></listitem>
+ <listitem><para>&DTV-INVERSION; = INVERSION_AUTO</para></listitem>
+ <listitem><para>&DTV-SYMBOL-RATE; = 5217000</para></listitem>
+ <listitem><para>&DTV-INNER-FEC; = FEC_3_4</para></listitem>
+ <listitem><para>&DTV-TUNE;</para></listitem>
+ </itemizedlist>
+
+<para>The code that would do the above is:</para>
+<programlisting>
+#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;
+}
+</programlisting>
+
+<para>NOTE: While it is possible to directly call the Kernel code like the
+ above example, it is strongly recommended to use
+ <ulink url="http://linuxtv.org/docs/libdvbv5/index.html">libdvbv5</ulink>,
+ 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.</para>
+