Low-impedance time-domain reflectometry for measuring the impedance characteristics of low-impedance transmission lines

2003 ◽  
Vol 74 (12) ◽  
pp. 5204-5211 ◽  
Author(s):  
N. G. Paulter ◽  
R. H. Palm ◽  
A. R. Hefner ◽  
D. W. Berning
Keyword(s):  
Transmission Lines ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Impedance Characteristics

Use of Time-Domain Reflectometry (TDR) to measure the water-content of sandy soils

Soil Research ◽  
1995 ◽  
Vol 33 (2) ◽  
pp. 265 ◽  
Author(s):  
PJ Gregory ◽  
R Poss ◽  
J Eastham ◽  
S Micin
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Transmission Lines ◽  
Time Domain ◽  
Water Storage ◽  
Sandy Soils ◽  
Time Domain Reflectometry ◽  
Soil Water Storage ◽  
Use Of Time ◽  
Daily Evaporation

We investigated the potential sources of error when using time domain reflectometry (TDR) to measure the water content of sandy soils and evaluated the technique as a means of measuring evaporation from columns of soil and changes in soil water storage beneath crops. Inaccurate depth location of the transmission lines or the development of a hole at the tip of the transmission lines introduced an error about 10 times larger than the errors associated with hardware and software. Calibration in two sandy soils gave a curve of similar shape to that found by others except for values of dielectric constant < 6 when measured values of water content were less than those expected. Daily evaporation from soil columns measured by weighing and with TDR showed large differences between the two techniques (up to 32%) but compensating errors over time allowed cumulative evaporation to be estimated with TDR to within 6.6% of that determined by weighing over a 162 h period. Under field conditions, the agreement between TDR and neutron probe measures of changes in soil water storage in the upper 0.3 m was good and generally within 10% over both 14 day and longer periods.

scholarly journals Locating the frozen–unfrozen interface in soils using time-domain reflectometry

1982 ◽  
Vol 19 (4) ◽  
pp. 511-517 ◽  
Author(s):  
T. H. W. Baker ◽  
J. L. Davis ◽  
H. N. Hayhoe ◽  
G. C. Topp
Keyword(s):  
Transmission Lines ◽  
Time Domain ◽  
Freezing Temperature ◽  
Time Domain Reflectometry ◽  
Temperature Measurements ◽  
Soil Freezing ◽  
Electromagnetic Pulses ◽  
The Time Domain ◽  
Time Domain Reflectometer ◽  
Liquid And Solid Phases

The time-domain reflectometry technique was compared with the temperature measurement method for locating the frozen–unfrozen interface in water and sandy soils. This technique depends on the high-frequency (1–1000 MHz) electrical properties of water that change significantly and abruptly between the liquid and solid phases. Parallel wire transmission lines were inserted into the soil to guide electromagnetic pulses produced by a time-domain reflectometer (TDR). The frozen–unfrozen interface produced reflections measured by the TDR which were in turn used to locate the interface as it moved along the transmission line. In the laboratory it was possible to locate the interface using the TDR to within ±0.5 cm and in the field to within ±2.4 cm. These errors were equal to those associated with the temperature measurements. Keywords: soil freezing, temperature measurements, dielectric constant, time-domain reflectometry.

scholarly journals Determination of ice-shelf bottom melting by time-domain reflectometry

1993 ◽  
Vol 39 (132) ◽  
pp. 353-356
Author(s):  
K. Grosfeld ◽  
N. Blindow
Keyword(s):  
Transmission Lines ◽  
Time Domain ◽  
High Reliability ◽  
Melting Rate ◽  
Time Domain Reflectometry ◽  
Ice Shelf ◽  
Wave Forms ◽  
A New Technique ◽  
Tape System

AbstractFor our work in the Filchner-Ronne Ice Shelf Programme (FRISP), we have developed a new technique for measuring the bottom-melting rate with high reliability. The method is based on time-domain reflectometry (TDR) measurements of transmission lines inserted into melt holes. The TDR-data are digitally recorded on magnetic tape. System resolution has been estimated at 0.2 m. Hence, re-measuring after 1 year gives an accuracy of 10% for melting rates of 2m a-1. Two transmission lines for TDR measurements were installed during the German FRIS Expedition 1989–90. This paper describes the design of the system. Examples of recorded wave forms are given.

scholarly journals Determination of ice-shelf bottom melting by time-domain reflectometry

1993 ◽  
Vol 39 (132) ◽  
pp. 353-356 ◽  
Author(s):  
K. Grosfeld ◽  
N. Blindow
Keyword(s):  
Transmission Lines ◽  
Time Domain ◽  
High Reliability ◽  
Melting Rate ◽  
Time Domain Reflectometry ◽  
Ice Shelf ◽  
Wave Forms ◽  
A New Technique ◽  
Tape System

AbstractFor our work in the Filchner-Ronne Ice Shelf Programme (FRISP), we have developed a new technique for measuring the bottom-melting rate with high reliability. The method is based on time-domain reflectometry (TDR) measurements of transmission lines inserted into melt holes. The TDR-data are digitally recorded on magnetic tape. System resolution has been estimated at 0.2 m. Hence, re-measuring after 1 year gives an accuracy of 10% for melting rates of 2m a-1. Two transmission lines for TDR measurements were installed during the German FRIS Expedition 1989–90. This paper describes the design of the system. Examples of recorded wave forms are given.

Spread Spectrum Time Domain Reflectometry With Lumped Elements on Asymmetric Transmission Lines

2021 ◽  
Vol 21 (2) ◽  
pp. 921-929 ◽  
Author(s):  
Ayobami S. Edun ◽  
Naveen Kumar Tumkur Jayakumar ◽  
Samuel R. Kingston ◽  
Cynthia M. Furse ◽  
Michael A. Scarpulla ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Time Domain ◽  
Spread Spectrum ◽  
Time Domain Reflectometry ◽  
Asymmetric Transmission ◽  
Lumped Elements
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