The CS650 consists of two 30-cm-long stainless steel rods connected
to a printed circuit board. The circuit board is encapsulated in epoxy
and a shielded cable is attached to the circuit board for datalogger
The CS650 measures propagation time, signal attenuation, and
temperature. Dielectric permittivity, volumetric water content, and
bulk electrical conductivity are then derived from these raw values.
Measured signal attenuation is used to correct for the loss effect on
reflection detection and thus propagation time measurement. This
loss-effect correction allows accurate water content measurements in
soils with bulk EC ≤0.8 dS m without performing a soil specific calibration.
Soil bulk electrical conductivity is also calculated from the
attenuation measurement. A thermistor in thermal contact with a probe
rod near the epoxy surface measures temperature. Horizontal
installation of the sensor provides accurate soil temperature
measurement at the same depth as the water content. Temperature
measurement in other orientations will be that of the region near the
rod entrance into the epoxy body.