.. _alc:

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Automatic Level Control
=======================

The SRS-3 uses an Automatic Level Control (ALC) loop to adjust the transmit gain to achieve the target output power (set through the ``tx.pout`` property).

The ALC can be configured to 3 different modes, set through the ``tx.alc.mode`` property. The other ``tx.alc.*`` properties should not be adjusted without consulting Satlab. The default mode is full ALC (mode 2).

Mode 0:
  Manual mode. The gain is set through the ``tx.gain`` property and is not adjusted by the system.
Mode 1:
  Open-loop ALC. The system uses the target output power to calculate the gain from the factory calibrated gain lookup table, but does not adjust the gain based on the achieved output power.
Mode 2:
  Full ALC. The gain is calculated using the lookup table for the first packet in a burst, and is subsequently adjusted based on the achieved output power.

The measured output power of the last transmitted frame is always available in the ``tx.pwr.fwd`` property.
