<refentry id="FE_SET_VOLTAGE">
  <refmeta>
    <refentrytitle>ioctl FE_SET_VOLTAGE</refentrytitle>
    &manvol;
  </refmeta>

  <refnamediv>
    <refname>FE_SET_VOLTAGE</refname>
    <refpurpose>Allow setting the DC level sent to the antenna subsystem.</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcprototype>
	<funcdef>int <function>ioctl</function></funcdef>
	<paramdef>int <parameter>fd</parameter></paramdef>
	<paramdef>int <parameter>request</parameter></paramdef>
	<paramdef>enum fe_sec_voltage *<parameter>voltage</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Arguments</title>
        <variablelist>
      <varlistentry>
	<term><parameter>fd</parameter></term>
	<listitem>
	  <para>&fe_fd;</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><parameter>request</parameter></term>
	<listitem>
	  <para>FE_SET_VOLTAGE</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><parameter>voltage</parameter></term>
	<listitem>
	  <para>pointer to &fe-sec-voltage;</para>
	  <para>Valid values are described at &fe-sec-voltage;.</para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Description</title>

<para>This ioctl allows to set the DC voltage level sent through the antenna
    cable to 13V, 18V or off.</para>
<para>Usually, a satellite antenna subsystems require that the digital TV
    device to send a DC voltage to feed power to the LNBf. Depending on the
    LNBf type, the polarization or the intermediate frequency (IF) of the LNBf
    can controlled by the voltage level. Other devices (for example, the ones
    that implement DISEqC and multipoint LNBf's don't need to control the
    voltage level, provided that either 13V or 18V is sent to power up the
    LNBf.</para>
<para>NOTE: if more than one device is connected to the same antenna,
    setting a voltage level may interfere on other devices, as they may lose
    the capability of setting polarization or IF. So, on those
    cases, setting the voltage to SEC_VOLTAGE_OFF while the device is not is
    used is recommended.</para>

&return-value-dvb;
</refsect1>

</refentry>
