Operating Manual

Chapter 5 Radar Fine Tuning Accu-Wave
5-2 TN Technologies
4. False Echo Management
There can be several sources of radar echoes other than the material surface. If the
automatic echo selection criteria are adequate for identifying the echo from the
surface in your application, this menu provides tools to help the system select the
proper echo.
From the measurement display, use the → key to scroll to the “Radar fine tuning” menus.
Press ↓ to enter this menu group and to scroll to the four menu groups listed above. Each
of these four menu groups is discussed in more detail in the following sections.
Material Type and Measurement Head Setup
The “Material type and measurement head setup” menus allow you to enter information
regarding the characteristics of your process material, the process seal, the system to
determine the expected signal strength and any distance offset which might be caused by
your specific process seal. Unless material information is entered, the system uses low
initial amplification to prevent saturation. This configuration will serve in most
applications due to the system’s very broad dynamic range.
If the return signal is weak due to a combination of factors such as a low dielectric process
material plus agitation, the situation may be improved by entering information about the
material. If you select “is not” water based material, the system will increase the initial
amplification to a moderate level. Entering the dielectric constant for your particular
material will allow the system to optimize the initial amplification.
If there are features in your tank that produce a stronger echo than the surface of the
process material, you may see saturation warnings during operation. In this case, you will
need to change the dielectric entry to a higher value. (The gain or amplification setting for
the microwave signal is determined based on the value of the dielectric constant, as the
value of the dielectric constant is increased, the amplification level is decreased.) Even
though such offending signals may be stronger than the proper signal, the system can still
be tuned to select the proper echo. It is important, however, that the initial amplification be
set so that the strongest echo does not cause saturation.
The “spectrum count to average” entry allows the system to enhance weak echoes by
averaging several samples. An entry greater than 8 can slow the response to level changes.
The spectrum averaging is performed prior to performing the echo limiting and echo
rejection tests. Typically, this entry should be left at 1.0 (the default value).
The “Material Type and Measurement Head Setup” menu items are summarized in the
following table.