Time domain reflectometry liquid level sensors

The technique of time domain reflectometry (TDR) has been used by electrical engineers for testing the characteristics of transmission lines and diagnosing faults. Although TDR instruments for testing cable are commonly used today, few instrumentation engineers are aware that the technique can measure liquid levels and fluid interfaces. In this article, I review the theory and principles of time domain reflectometry and present the application of this technology as a liquid level sensor