Electromagnetic position detector employing fast fourier transform analysis

摘要

A high frequency signal is beamed into a bunker and a reflected signal from the top of the contents in the bunker is detected and fed into electronic circuitry. This circuitry obtains a beat signal dependent in frequency on the height of material in the bunker and the signal is subjected to division in a processing circuit and subsequent treatment as a Fast Fourier transform. A store gathers all divided and transformed segments of the signal to provide a spectrum from which the level of the bunker can be obtained as a read out.