Definition - TDT
With Time Domain Transmissometry (TDT), a step pulse with a fast rise time is transmitted into a transmission line. The step pulse travels down the transmission line and a voltage threshold is detected at the other end of the transmission line.
2 million of these pulses are generated every second and the sensor will display an average reading. There is no complex waveform analysis as with TDR.
The shape of the transmitted waveform is not relevant, but a measurement of the pulse travel time through the transmission line will allow an estimate of the dielectric constant of the medium.
One of the properties of TDT is that the one-way travel time of the pulse through a transmission line through the medium is directly related to the moisture content of the medium, e.g. the more moisture in the material, the longer the trip time.
The E.S.I. GroPoint and Flo·Point™ products use Time Domain Transmissometry (TDT) as a basis of measurement of water content.
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