KROHNE BM 102 Handbook - Manual (Page 54)

54 BM 102
Automatic adjustment:
To maintain a sufficiently strong reflection signal, the gain is adjusted automatically. When the
amplitude of the level reflection decreases, the gain will increase to compensate for the loss in
signal amplitude. Gain and level threshold thus maintain the same proportion.
At gain 3, the level signal (1) is located between a distance of 2 and 4 metres or 6.5 and 13 ft. (2) is
the level threshold. This is shown below:
The level has dropped, increasing the distance between the product and the flange. The reflection
signals for level (1) and interference signals (3) have become weaker (smaller amplitude). The
interference signals are now below the level threshold (2), whose lower limit is 50 mV. As in the
diagram above, the amplification factor is 3. Refer to the graph below:
In both cases, the automatically adjusted gain of the threshold indicates all signals located above
one-half of the amplitude of the level signal.
In the event of operational or installation faults, you can frequently identify the cause of the fault
by means of this function and normally eliminate it yourself. Should the fault persist, please send
a copy of the screen (screen shots with F10) to your KROHNE Service Centre. A list of service
centres for each country is supplied on the back page of this handbook.