Lightning Audio 7532 manual Function and system design, Measuring principle, Input

7532 Appendix

11.4Function and system design

11.4.1Measuring principle

The 7500 RTG is a "downward-looking" measuring system, operating based on the time-of-flight method. It measures the distance from the reference point (process connection) to the product surface. Radar impulses are emitted by an antenna, reflected off the product surface and received again by the radar system.

00-00-en-001

L00-FMR53xxx-15-

Input

The reflected radar impulses are received by the antenna and transmitted into the electronics. A microprocessor evaluates the signal and identifies the level echo caused by the reflection of the radar impulse at the product surface. The unambiguous signal identification is accomplished by the PulseMaster® software based on many years of experience with time-of-flight technology. The mm-accuracy of the 7500 RTG is achieved with the patented algorithms of the PhaseMaster® software.

The distance D to the product surface is proportional to the travel time t of the impulse:

D = c · t/2,

with c being the speed of light.

Based on the known empty distance E, the level L is calculated:

L = E – D

Reference point for "E" is the lower surface of the process connection.

The 7500 RTG is equipped with functions to suppress interference echoes. The user can activate these functions. They ensure that interference echoes (e.g. from edges and weld seams) are not interpreted as level echo.

97