Siemens Sitrans LR250, Руководство по эксплуатации, Страница: 234 / 306

Appendix A: Technical reference
A.2 Echo processing
SITRANS LR250 (PROFIBUS PA)
232
Operating Instructions, 08/2014, A5E32221386-AC
A.2 Echo processing
A.2.1 Process Intelligence
The signal processing technology embedded in Siemens radar level devices is known as
Process Intelligence.
Process intelligence provides high measurement reliability regardless of the dynamically
changing conditions within the vessel being monitored. The embedded Process Intelligence
dynamically adjusts to the constantly changing material surfaces within these vessels.
Process Intelligence is able to differentiate between the true microwave reflections from the
surface of the material and unwanted reflections being returned from obstructions such as seam
welds or supports within a vessel. The result is repeatable, fast and reliable measurement. This
technology was developed as result of field data gained over some twenty years from more than
1,000,000 installations in many industries around the world.
Higher order mathematical techniques and algorithms are used to provide intelligent processing
of microwave reflection profiles. This "knowledge based" technique produces superior
performance and reliability.
A.2.2 Echo Selection
Time Varying Threshold (TVT)
A Time Varying Threshold (TVT) hovers above the echo profile to screen out unwanted
reflections (false echoes).
In most cases the material echo is the only one which rises above the default TVT.
In a vessel with obstructions, a false echo may occur. See Auto False Echo Suppression
(Page 236) for more details.