transmission line signal attenuation. The CS650 handles this problem by making an electrical
conductivity measurement then correcting the oscillator period accordingly. On-board
processing within the sensor head calculates electrical conductivity from the signal attenuation
measurement and combines the result with the oscillation period measurement to calculate the
dielectric permittivity of the media and finally applies the Topp equation (Topp et al. 1980) to
estimate volumetric water content.
Sensor electronics are encapsulated in the rugged epoxy sensor head.
A five-conductor cable including the drain or shield wire provides power and ground as well as
communications with the CS650. The CS650 is intended to communicate with SDI-12 recorders,
including Campbell Scientific data loggers. Alternatively, use the orange wire to transmit and
receive RS-232. The A200 USB-to-Serial Module allows RS-232 communications between a
computer and the CS650 by means of Campbell Scientific’s
Device Configuration Utility
software.
Features:
l
Measurement corrected for effects of soil texture and electrical conductivity
l
Estimates soil-water content for a wide range of mineral soils
l
Versatile sensor—measures dielectric permittivity, bulk electrical conductivity (EC), and soil
temperature
l
Compatible with Campbell Scientific CRBasic data loggers: CR6 series, CR3000, CR1000X
series, CR800 series, CR300 series, and CR1000
6. Specifications
(p. 6) compares the size of the CS650 and CS655 reflectometers.
Table 6-1: Size specifications
CS650
CS655
Rods
300 mm long
3.2 mm diameter
32 mm spacing
120 mm long
3.2 mm diameter
32 mm spacing
Sensor head
L 85 mm
W 63 mm
D 18 mm
L 85 mm
W 63 mm
D 18 mm
CS650 and CS655 Water Content Reflectometers
6
