fe-set-voltage.rst (1624B)
1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2.. c:namespace:: DTV.fe 3 4.. _FE_SET_VOLTAGE: 5 6******************** 7ioctl FE_SET_VOLTAGE 8******************** 9 10Name 11==== 12 13FE_SET_VOLTAGE - Allow setting the DC level sent to the antenna subsystem. 14 15Synopsis 16======== 17 18.. c:macro:: FE_SET_VOLTAGE 19 20``int ioctl(int fd, FE_SET_VOLTAGE, enum fe_sec_voltage voltage)`` 21 22Arguments 23========= 24 25``fd`` 26 File descriptor returned by :c:func:`open()`. 27 28``voltage`` 29 an integer enumered value described at :c:type:`fe_sec_voltage` 30 31Description 32=========== 33 34This ioctl allows to set the DC voltage level sent through the antenna 35cable to 13V, 18V or off. 36 37Usually, a satellite antenna subsystems require that the digital TV 38device to send a DC voltage to feed power to the LNBf. Depending on the 39LNBf type, the polarization or the intermediate frequency (IF) of the 40LNBf can controlled by the voltage level. Other devices (for example, 41the ones that implement DISEqC and multipoint LNBf's don't need to 42control the voltage level, provided that either 13V or 18V is sent to 43power up the LNBf. 44 45.. attention:: if more than one device is connected to the same antenna, 46 setting a voltage level may interfere on other devices, as they may lose 47 the capability of setting polarization or IF. So, on those cases, setting 48 the voltage to SEC_VOLTAGE_OFF while the device is not is used is 49 recommended. 50 51Return Value 52============ 53 54On success 0 is returned. 55 56On error -1 is returned, and the ``errno`` variable is set 57appropriately. 58 59Generic error codes are described at the 60:ref:`Generic Error Codes <gen-errors>` chapter.