NGM uses TDR (Time Domain Reflectometry) technology, which is also known as Guide Microwave or Guided Wave Radar. This means that low-energy and high-frequency electromagnetic impulses, generated by the sensor’s circuitry, are propagated along the probe which is immersed in the liquid or solid to be measured.

When these impulses hit the surface of the media, part of the impulse energy is reflected back up the probe to the circuitry which then calculates the level from the time difference between the impulses sent and the impulses reflected. The sensor can output the analysed level as 4 ... 20 mA analogue output, or it can convert the values into freely programmable switching output signal.