Operating Instructions

Table Of Contents
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.3.2 Time Varying Threshold (TVT) Curves
A Time Varying Threshold (TVT) curve hovers above the echo profile to screen out unwanted
reflections (false echoes).
TVT curve Low Cal. Pt.
Sensor reference point True echo
High Cal. Pt. = 0 Echo marker
Obstruction at 1.2 m False echo
Material level at 2.9 m
In most cases the material echo is the only one which rises above the default TVT curve. In a
vessel with obstructions a large false echo may rise above the default TVT. The Auto False
Echo Suppression feature (see below) can be used to screen it out.
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, amongst other
characteristics.
The true echo is selected based on the setting for the Echo selection algorithm (Algorithm
2.2.4.1.1 (Page 82)).
Appendix A: Technical reference
A.3 Echo Processing
SITRANS LR260 with mA/HART
152 Operating Instructions, 11/2019, A5E32337683-AD