Radar and TDR

Continuous level measurement via radar and TDR is based on the theory of the propaga-tion of electromagnetic waves, put forth by the British physcist James C. Maxwell in 1865. Maxwell postulated that the field lines of a changing magnetic field are surrounded by annualar electrical field lines, even in the absence of electrical conductors.Inspired by this theory, German physicist Christian Hülsmeyer immediately applied for a patent for his telemobiloscope, the first radar device of this type in Düsseldorf in 1904. For this innovation, he is rightly known as the the inventor of the "original radar."In 1989, KROHNE introduced the first radar level counter for process tanks.
BM 70 for measuring bitumen for the PCK

FMCW radar: Frequency Modulated Continuous Wave

The FMCW radar measuring principle: For FMCW radar, a high-frequency signal is used, the transmitting frequency of which increases linearly during the measurement (frequency sweep). The signal is sent out, reflected back from the surface of the measured product and received with a time delay. The difference T f is formed from the current transmitting and receiving frequency for further signal processing. It is directly proportional to the distance, i.e. a large frequency difference means a large distance and vice versa.This frequency difference is converted to a frequency spectrum via a „Fast Fourier Transformation“ (FFT), then the product distance is calculated. The level results from the difference between the tank level and distance.