Specifications – Campbell Scientific CS616 and CS625 Water Content Reflectometers User Manual
Page 8
CS616 and CS625 Water Content Reflectometers
The CS625 output is a square wave output and can be connected to Campbell
Scientific CR200(X) series dataloggers. A CRBasic program using Period
Averaging is used to measure the probe output period and convert to
volumetric water content using calibration equations.
The water content reflectometer consists of two stainless steel rods connected
to a printed circuit board. A shielded four-conductor cable is connected to the
circuit board to supply power, enable the probe, and monitor the pulse output.
The circuit board is encapsulated in epoxy.
High-speed electronic components on the circuit board are configured as a
bistable multivibrator. The output of the multivibrator is connected to the
probe rods which act as a wave guide. The travel time of the signal on the
probe rods depends on the dielectric permittivity of the material surrounding
the rods and the dielectric permittivity depends on the water content.
Therefore, the oscillation frequency of the multivibrator is dependent on the
water content of the media being measured. Digital circuitry scales the
multivibrator output to an appropriate frequency for measurement with a
datalogger. The water content reflectometer output is essentially a square
wave. The probe output period ranges from about 14 microseconds with rods
in air to about 42 microseconds with the rods completely immersed in typical
tap water. A calibration equation converts period to volumetric water content.
The CS616/CS625's cable can terminate in:
•
Pigtails that connect directly to a Campbell Scientific datalogger
(option –PT).
•
Connector that attaches to a prewired enclosure (option –PW). Refer
to
for more information.
5. Specifications
Features:
•
High accuracy and high precision
•
Fast response time
•
Designed for long-term unattended water content monitoring
•
Probe rods can be inserted from the surface or buried at any
orientation to the surface
CS616 Compatibility
Dataloggers:
CR800 series
CR1000
CR3000
CR5000
CR510
CR10X
CR23X
2