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Configuration and Analysis with DTM via IO-Link
Application Information for Echo Suppression
In order to be able to suppress echoes, you first have to set the "Echo suppression" parameter
to "enabled," provided that the parameter is not already set accordingly in the connected sen-
sor. The "Start automatic echo suppression" button as well as the parameter values of the avail-
able suppression areas 1
–
10 are then displayed in the DTM.
Ideally, echo suppression areas should be based on a variety of echo samples (at least 50)
because the echo amplitude can vary from measurement to measurement depending on the
ambient conditions.
Obtaining sampled echoes from the original sensor mounting location in the plant is mandatory
before starting targeted echo suppression.
Automatic Echo Suppression
If the echo from the target object is also contained in the echo samples, this will be suppressed
through automatic echo suppression. This may occur, for example, when echo samples are
taken in a partially-filled tank because then the echo from the surface of the liquid is also
included in the echo samples.
The same applies in the case where samples are carried out in an empty tank because the
echo from the base of the tank in most cases should still be identified as "Tank empty," even
after echo suppression.
In these cases, a manual correction must be carried out to the corresponding suppression area
to eliminate the relevant echo from the suppression (see section on "Manual echo suppres-
sion").
A lot of "Echo blocks" in the echo samples may lead to the 10 available suppression areas not
being sufficient for algorithm-based automatic suppression to really suppress all recorded
echoes. In this case, it is necessary to carry out manual adjustments to the individual suppres-
sion areas (see section on "Manual echo suppression").
Manual Echo Suppression
Each of the 10 suppression areas is specified via the "Start point," "Amplitude," and "Length"
parameters (see section on "Menu description"). Each area can be modified or deleted individ-
ually or all at once.
To reliably suppress echoes under varying ambient conditions (for example fluctuations of air
temperature or air humidity), we recommend selecting a suppression area which is larger than
the echo or echo block to be suppressed. Specifically, this means that the amplitude value of
the suppression area should be set at least 10 % higher than the largest echo amplitude to be
suppressed. However, the amplitude value should not be set so high that the echo to detect
(e.g., a fill level) is no longer recognized. For indoor applications, the lateral boundaries of the
suppression area should be set to +/- 5 % and for outdoor applications to +/- 10% of the rele-
vant echo distances, which should be suppressed with the area.
