LEVELS [Goal] [/READ]
Adjust the receiver attenuators to optimize the total power and
correlator levels. Goal is the desired total power level, and should be
between 100 and 200 (default 170, giving best efficiency). The
adjustment should be made around the lowest elevation used for the
observation.
If option /READ is present, do not adjust the attenuator, but read
their values from the microprocessors.