Tokyo Keiki KRG-10, User Manual

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7-2
7.3 Avoiding noise echo
(1) Masking near antenna
Depending on the shape of the tank, there is sometimes a strong noise echo due to intense
multiple reflection between the tank and the surface near the antenna. If affected by this, the
surface level might not be able to be measured properly. In this case, you can set the setting
parameter "H" to avoid that effect.
(2) Masking due to the noise table
If the reflection echo cannot be recognized normally due to the strong noise level, you can use the
noise table or rejecter to set the threshold value for recognizing the signal to a value greater than
the noise level. Doing so will allow stable measurement to be performed. The threshold value
according to the noise table or rejector can be set using the configuration software. The noise
table consists of a line graph connecting a maximum of 513 points. The rejecter is the straight line
that indicates the minimum value of the signal amplitude of the noise table. A threshold value can
be set for each point by using the noise table. Use the setting software to read the signal
amplitude in the tank before setting the noise table. For information on how to set the threshold
value, refer to
6.8 Echo Viewer .
A setting example of the threshold value is shown in the following figure. Signals smaller than the
threshold level of the noise table shown in the figure are ignored.
Surface Echo
Distance
Noise Table
Noise
Noise
3dB
≧ （ Recommended Value ）
Fig. 7.3.1 Setting example of threshold value