Amplifier characterization
==========================

``AmplifierTest`` determines small-signal gain, the 1 dB and 3 dB
compression points, and permissible input levels. The script supports two
measurement setups.

Measurement setups
------------------

``rack``
   The amplifier is installed in a measurement rack. Directional couplers
   and power meters acquire forward and reverse power.

``direct``
   The isolated amplifier output is connected to an output power sensor
   through a cable and attenuator. The DOT graph describes the path
   corrections.

Virtual runs
------------

.. code-block:: console

   python script/amplifier-test.py \
       script/conf/amplifier-test-virtual/conf.py

.. code-block:: console

   python script/amplifier-test.py \
       script/conf/amplifier-test-direct-virtual/conf.py

The direct configuration is also used by the
:doc:`../framework/tutorial`. Start the Qt interface with
``amplifier-test-qt.py`` and the same configuration.

Evaluation
----------

When evaluation is enabled, the class generates an amplifier INI with these
channels:

``S21``
   Gain as a function of frequency.

``C1DB`` and ``C3DB``
   Input levels at the identified compression points. Compression points
   that were not found are not emitted as invalid numbers.

``MAXIN``
   Selected maximum input level, using the 1 dB compression point by default.

Frequency, value, and complex interpolation are selected explicitly in
``evaluation_parameters``. Typical logarithmic RF support points and gain
values expressed in dB use ``LOG``, ``DB``, and ``POLAR``.

Protection
----------

Amplifier limits are enforced through ``AmplifierProtect`` from the MGraph.
In the direct setup, the power meter may additionally provide a ``MAXIN``
channel. Before setting a new level, the workflow estimates the power at the
sensor from the current path corrections.

Virtual tests do not replace measurement physics. They verify workflow, graph
correction, protection, logging, pickle output, and resume behavior.
Compression data become meaningful only with a suitable real or deliberately
simulated characteristic.