Campbell Scientific -
Time Domain Reflectometry (TDR) is widely used to measure soil water content, bulk electrical conductivity, and rock mass deformation. TDR measurements are nondestructive and offer excellent accuracy and precision.
The principal components of a TDR system are the CSI data logger, TDR100 Reflectometer, SDMX50-series coaxial multiplexers, interconnecting cabling, and TDR probes. The TDR100 is controlled using PCTDR Windows software or using a TDR100 instruction with a CR1000 or CR3000 data logger. Typically the system is powered with a user-supplied, deep-cycle battery that is recharged by a 20 watt solar panel. Installations that have access to ac power may be able to use the PS100 sealed rechargeable battery in a CR1000 installation, or the CR3000's rechargeable battery. The system components are:
TDR100 Time Domain Reflectometer
The TDR100 Time-Domain Reflectometer is the core of the Campbell Scientific Time Domain Reflectometry system. The TDR100 (1) generates a very short rise time electro-magnetic pulse that is applied to a coaxial system which includes a TDR probe for soil water measurements and (2) samples and digitizes the resulting reflection waveform for analysis or storage. The elapsed travel time and pulse reflection amplitude contain information used by the on-board processor to quickly and accurately determine soil volumetric water content, soil bulk electrical conductivity, rock mass deformation or user-specific, time-domain measurement.
