Campbell TDR100 Instrukcja Obsługi Pobierz pdf (Strona 24)

TDR100

5.8.1 Determining Probe Constant, K

, 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

) to give bulk electrical conductivity in S/m (Siemens/meter). The

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 CR10X and CR23X Datalogger Instruction 119

parameter data

type

value description

SDM address 1: 2 (00)

(33)

Address of TDR100

see Table 5-1

Output option 2: 4 0 Returns L

1 Returns vector of n + 9 values from TDR100

with n the number of waveform data points

selected. Elements 1-9 contain key Instruction

119 parameter values. Then next n elements are

reflection waveform values.

2 Returns the waveform plus the first derivative of

the waveform

3 Electrical conductivity option. See section on

probe constants for electrical conductivity

measurements.

Multiplexer and probe 3:

selection

4 See Section 5.1.1 for address protocol

Waveform Averaging 4: FP 1 -

128

Number of reflections averaged by the TDR100.

5: FP .1 - 1 relative propagation velocity

Points 6: FP 20-

2048

number of points in waveform

Cable length (meters) 7: FP 0 -

2100

distance for TDR100 corresponding with

beginning of waveform

Window Length

(meters) 8:

FP .1 -

700

length of reflection waveform

Probe length 9: 4 Physical length of the exposed portion of the

metal rods

Probe offset 10: FP 0 -

1.0

Accounts for portion of rods not exposed to soil.

See Section 6.2.10.

Input location 11: 4 Input storage location for measurement result. If

waveforms are chosen for output, this location is

occupied by the first data point.

Multiplier 12: FP Multiplication factor applied to La/L and stored

in input location specified in parameter 11.

Set to 1 when parameter 2 is 1 or 2.

For electrical conductivity, can be used for probe

constant value.

Offset 13: FP Offset value added to La/L and stored in input

location specified in parameter 11. Set to 0 when

parameter 2 is 1 or 2.

1 2 ... 19 20 21 22 23 24 25 26 27 28 29 ... 55 56

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