Appendix A: Technical reference
A.2 Echo processing
SITRANS LR250 (PROFIBUS PA)
Operating Instructions, 08/2014, A5E32221386-AC
233
①
default TVT
②
echo profile
③
material level
④
echo marker
The device characterizes all echoes that rise above the TVT as potential good echoes. Each
peak is assigned a rating based on its strength, area, height above the TVT, and reliability,
amongst other characteristics.
Algorithm (2.5.7.1.)
The true echo is selected based on the setting for the Echo selection algorithm. Options are true
First Echo, Largest Echo, or best of First and Largest.
Position Detect (2.5.7.2.)
The echo position detection algorithm determines which point on the echo will be used to
calculate the precise time of flight, and calculates the range using the calibrated propagation
velocity (see Propagation Factor (2.5.3.) for values). There are three options:
●
Center
●
Hybrid
●
CLEF (Constrained Leading Edge Fit)