Material level sensing system calibration

摘要

A system for measuring level of material in a vessel that includes a transmission line probe adapted to be positioned for contact with material in the vessel. Electronics are coupled to the transmission line probe for launching microwave radiation along the probe and detecting radiation reflected by the electrical impedance discontinuity presented at the air/material interface in the vessel. Level of the air/material interface within the vessel is determined employing time domain reflectometry techniques, and is displayed as a continuous function over a predetermined range. The system range is calibrated by means of a target selectively manually positionable along the probe rod while the probe is disposed outside of the vessel. First and second signals are selectively stored in the system electronics with the target disposed at positions along the probe rod corresponding to the ends of the material level measurement range. The electronics are thereafter operable to display level of the air/material interface along the probe within the vessel over the predetermined range between the selected positions of the target along the probe rod. The end of the probe rod is at an angle of 90 DEG to the remainder of the probe to eliminate material level ambiguity at the probe end.