Operating Manual

Chapter 5 Radar Fine Tuning Accu-Wave
5-14 TN Technologies
Example: Locking on to False Target Closer (higher) than Material Surface
When the process material has a low dielectric constant, the return signal from the material
surface can be weaker than the echoes from false targets. If there is a pipe or other artifact
(false target) in the tank above the surface level of the process material, the gauge may
lock on to the echo from the false target with the strongest signal rather than locking on to
the proper echo from the material surface.
Note: If the dielectric constant of the process material is below two, call TN
Technologies and speak with a Microwave Applications Specialist.
To make the system favor the more distant (proper) target, enter a larger value for the
successive weight factor. Use a weighting factor large enough so that the signal strength of
the proper target multiplied by the weighting factor is at least twice as large as the signal
strength of any of the closer, false echoes.
In some instances, using a large weighting factor (to deal with close echoes) can cause the
system to lock on to bottom of tank. Use the ‘bottom echo signal strength factor” and
“Distance REF LINE to tank bottom” menu items to mask the tank bottom.
Example: Locking on to False Target Farther (lower) than Material Surface
With high dielectric materials, such as water, multiple reflections can occur depending on
the shape of the tank. Use a smaller successive weighting factor to exclude these relatively
strong, more distant echoes. Select a weighting factor small enough so that the signal
strength of any false echo multiplied by the weighting factor is less than half as large as the
signal strength from the closer, proper target.
The use of a very small weighting factor to favor close echoes can cause the system can
lock on to relatively weak, close artifacts instead of the proper target. This complication
can often be handled by limiting the number of echoes processed. Be careful to ensure that
the number of echoes processed is large enough to always include the echo from the actual
material surface.