User's Manual

4-7
Edition 1. Ref. No: 307010E
Transmitter Setup
4.4 Disturbance Echo Handling.
When disturbing echoes appear in the approved measuring range they can be
filtered out by setting up a Noise Table.
4.4.1 Noise Table
A Noise Table adjusts the threshold level at various parts of the measurement
range. By setting the threshold level to an appropriate value the disturbing echo
will be suppressed by the transmitter.
A Noise Table is defined by ullage points and signal amplitude threshold val-
ues. A maximum of 10 points can be specified. Linear interpolation is used be-
tween the points. Make sure that the noise table box around a disturbing echo is
big enough to hide the disturbing echo, see illustration below.
If a disturbing echo appears you should start by checking the ullage and the
corresponding amplitude of the detected signal. This provides information about
the position of the disturbance and the noise threshold required to suppress the
disturbing echo.
Note! The transmitter may temporarily loose track of the surface when it passes the noise threshold.
+ 5 dB
Signal Amplitude
Ullage (m)
Point 1
Point 2 Point 3
Point 4
Radar signal
Noise table
Point 1
Point 2
Point 3
Point 4
Signal Amplitude