Campbell TDR200, Инструкция по эксплуатации

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TDR200-Based Time-Domain Reflectometry System
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4. Calculate a threshold value using:
threshold = a • (maximum derivative) + b • (mean from step 3) +
c • (standard deviation from step 3)
The values for a, b and c are 0, 1 and 2 respectively.
5. With the point of the maximum first derivative as the right hand point,
define a window of 10 waveform values. Incrementally move this window
toward the TDR200 until all values are less than the threshold calculated in
step 4.
6. Calculate the average of this window of values and use for the applied
signal.
7. Calculate the average of the last six waveform values and use for reflected
signal.
8. Apply equation [5] of Section 8.1 , TDR Principles
(p. 16)
, to calculate
electrical conductivity.
9. References
Bilskie, Jim. 1997. “Reducing Measurement Errors of Selected Soil Water
Sensors. Proceedings of the International Workshop on Characterization
and measurement of the hydraulic properties of unsaturated porous media.
387-396.
Giese, K., and R. Tiemann. 1975. “Determination of the complex permittivity
from thin-sample time domain reflectometry, Improved analysis of the
step response waveform,” Adv. Molec. Relax. Processes 7:45-49
Ledieu, J., P. De Ridder, P. De Clerck, and S. Dautrebande. 1986. “A method
of measuring soil moisture by time-domain reflectometry,” J. Hydrol.
88:319-328.
Or, D., S.B. Jones, J.R. Van Shaar, S. Humphries, and L. Koberstein. 2004.
User’s guide WinTDR. Version 6.1. Utah State Univ., Logan.
Topp, G.C., J.L. Davis & A.P. Annan. 1980. “Electromagnetic determination
of soil water content: measurements in coaxial transmission lines,” Water
Resources Research, v. 16, No. 3:574-582.
Wang, Z., Y. Kojima, S. Lu, Y. Chen, R. Horton, and R.C. Schwartz. 2014.
Time domain reflectometry waveform analysis with second order bounded
mean oscillation. Soil Sci. Soc. Am. J. 78:1146–1152.
doi:10.2136/sssaj2013.11.0497