Campbell Scientific TDR100 Time Domain Reflectometry Systems - Manual (Page 24)

TDR100
Campbell Scientific TDR Probes
CS605 CS610
General Description 3-rod probe
no balun required
stainless steel rods
3-rod probe
no balun required
stainless steel rods
Dimensions Rods:
30 cm length
0.476 cm diameter
Probe head:
cable-to-rod 10.8 cm
width 7.0 cm
thickness 1.9 cm
Rods:
30 cm length
0.476 cm diameter
Probe head:
cable-to-rod 10.8 cm
width 7.0 cm
thickness 1.9 cm
Cable type RG58 RG8 low loss
Cable length user-specified length user-specified length
Probe offset factor 0.085 m 0.085 m
Probe constant for
electrical
conductivity (Kp)
*see Section 5.8.1
1.74 1.74
5.8.1 Determining Probe Constant, K
p
, using PCTDR
Section 6.2.6 presents the principles for TDR measurements of soil electrical
conductivity. The result of the measurement must be multiplied by the probe
constant (K
p
) to give bulk electrical conductivity in S/m (Siemens/meter). The
K
p
value can be measured using PCTDR. The method requires submersion of
the TDR probe rods in de-ionized water of known temperature. See PCTDR
HELP for simple instructions.
6. Datalogger Instructions for TDR Measurements
6.1 CR800, CR850, CR1000, or CR3000 Datalogger Instruction
“TDR100”
The TDR100 instruction is used to measure one or more time domain
reflectivity (TDR) probes attached to a TDR100 device.
Syntax
TDR100 ( Dest, SDMAddress, Option, Mux/ProbeSelect, WaveAvg, Vp,
Points, CableLength, WindowLength, ProbeLength, ProbeOffset, Mult, Offset
Remarks
This instruction can be used to measure one TDR probe connected to the
TDR100 directly or multiple TDR probes connected to one or more SDMX50
multiplexers.
Dest: The Dest parameter is a variable or variable array in which to store the
results of the measurement. The variable must be dimensioned to accommodate
all of the values returned by the instruction, which is determined by the Option
parameter.
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