A time-domain optimization technique for the simultaneous reconstruction of the characteristic impedance, resistance and conductance of a transmission line

Lundstedt, Jonas; He, Sailing

doi:10.1163/156939396x01143

Cited by 25 publications

(20 citation statements)

References 10 publications

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“…Another possibility is to develop inversion algorithms based on a straightforward calculation of the wave propagation along the transmission line due to an incident voltage step. Here the response of the transmission line can be calculated either in the time domain [Lundstedt and Stroem, 1996;Lundstedt and He, 1996;Feng et al, 1999;Oswald, 2000;Todoroff and Lan Sun Luk, 2001;Lundstedt and Norgren, 2003;Rahman and Marklein, 2005;Greco, 2006] or in the frequency domain [Norgren and He, 1996;Heimovaara et al, 2004;Lambot et al, 2004;Leidenberger et al, 2006;Scheuermann and Huebner, 2009].…”

Section: Introductionmentioning

confidence: 99%

Spatial time domain reflectometry and its application for the measurement of water content distributions along flat ribbon cables in a full‐scale levee model

Scheuermann

Huebner

Schlaeger³

et al. 2009

Water Resources Research

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[1] Spatial time domain reflectometry (spatial TDR) is a new measurement method for determining water content profiles along elongated probes (transmission lines). The method is based on the inverse modeling of TDR reflectograms using an optimization algorithm. By means of using flat ribbon cables it is possible to take two independent TDR measurements from both ends of the probe, which are used to improve the spatial information content of the optimization results and to consider effects caused by electrical conductivity. The method has been used for monitoring water content distributions on a full-scale levee model made of well-graded clean sand. Flood simulation tests, irrigation tests, and long-term observations were carried out on the model. The results show that spatial TDR is able to determine water content distributions with an accuracy of the spatial resolution of about ±3 cm compared to pore pressure measurements and an average deviation of ±2 vol % compared to measurements made using another independent TDR measurement system.

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Section: Introductionmentioning

confidence: 99%

Spatial time domain reflectometry and its application for the measurement of water content distributions along flat ribbon cables in a full‐scale levee model

Scheuermann

Huebner

Schlaeger³

et al. 2009

Water Resources Research

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“…But many applications ask for the spatial moisture distribution in soils or building constructions along a given profile. A high spatial resolution can be achieved by exploiting the full information content in the reflected electromagnetic signals of the sensor line (Lundstedt and He, 1996;Norgren and He, 1996). A new reconstruction algorithm has been developed which uses the full information of the TDR signals measured on one or both sides of the line.…”

Section: Egumentioning

confidence: 99%

A fast TDR-inversion technique for the reconstruction of spatial soil moisture content

Schlaeger¹

2005

Preprint

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Spatial moisture distribution in natural soil or other material is a valuably information for many applications. Standard measurement techniques give only mean or punctual results. Therefore a new inversion algorithm has been developed to derive moisture profiles along single TDR sensor-probes. The algorithm uses the full information content of TDR reflection data measured from one or both sides of an embedded probe. The system consisting of sensor probe and surrounded soil can be interpreted as a nonuniform transmission-line. The algorithm is based on the telegraph equations for nonuniform transmission-lines and an optimization approach to reconstruct the distribution of the capacitance and effective conductance along the transmission-line with high spatial resolution. The capaci-tance distribution can be converted into permittivity and water content by means of a capacitance model and dielectric mixing rules. Numerical investigations have been carried out to verify the accuracy of the inversion algorithm. Single-and double-sided time-domain reflection data were used to determine the capacitance and effective conductance profiles of lossless and lossy materials. The results show that single-sided reflection data are sufficient for lossless (or low-loss) cases. In case of lossy material two independent reflection measurements are required to reconstruct a reliable capaci-tance profile. The inclusion of an additional effective conductivity profile leads to an improved capacitance profile. The algorithm converges very fast and yields a capacitance profile within a sufficiently short time. The additional transformation to the water content requires no significant calculation time.

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“…Different approaches have been developed to use TDR information for the determination of soil moisture profiles (multisection transmission lines: Hook et al, 1992;Feng et al, 1999; full wave inversion techniques: Pereira, 1997;Todoroff et al, 1998;Oswald, 2000;Heimovaara et al, 2004). A high spatial resolution can be achieved by exploiting the full information content in the reflected electromagnetic signals of the sensor line (Lundstedt and He, 1996;Norgren and He, 1996). A new reconstruction algorithm has been developed which uses the full information of the TDR signals measured on one or both sides of the line.…”

Section: Introductionmentioning

confidence: 99%

A fast TDR-inversion technique for the reconstruction of spatial soil moisture content

Schlaeger¹

2005

Hydrol. Earth Syst. Sci.

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Abstract. Spatial moisture distribution in natural soil or other material is a valuably information for many applications. Standard measurement techniques give only mean or punctual results. Therefore a new inversion algorithm has been developed to derive moisture profiles along single TDR sensor-probes. The algorithm uses the full information content of TDR reflection data measured from one or both sides of an embedded probe. The system consisting of sensor probe and surrounded soil can be interpreted as a nonuniform transmission-line. The algorithm is based on the telegraph equations for nonuniform transmission-lines and an optimization approach to reconstruct the distribution of the capacitance and effective conductance along the transmission-line with high spatial resolution. The capacitance distribution can be converted into permittivity and water content by means of a capacitance model and dielectric mixing rules. Numerical investigations have been carried out to verify the accuracy of the inversion algorithm. Single-and double-sided time-domain reflection data were used to determine the capacitance and effective conductance profiles of lossless and lossy materials. The results show that singlesided reflection data are sufficient for lossless (or low-loss) cases. In case of lossy material two independent reflection measurements are required to reconstruct a reliable capacitance profile. The inclusion of an additional effective conductivity profile leads to an improved capacitance profile. The algorithm converges very fast and yields a capacitance profile within a sufficiently short time. The additional transformation to the water content requires no significant calculation time.

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A time-domain optimization technique for the simultaneous reconstruction of the characteristic impedance, resistance and conductance of a transmission line

Cited by 25 publications

References 10 publications

Spatial time domain reflectometry and its application for the measurement of water content distributions along flat ribbon cables in a full‐scale levee model

Spatial time domain reflectometry and its application for the measurement of water content distributions along flat ribbon cables in a full‐scale levee model

A fast TDR-inversion technique for the reconstruction of spatial soil moisture content

A fast TDR-inversion technique for the reconstruction of spatial soil moisture content

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