Transmission line reflectometer using frequency-modulated continuous wave
First Claim
1. Apparatus for the monitoring of physical variables of an interface between materials related to the refractive indices of such materials comprisinga, a transmission line probe placed in the materials;
- b, means for generating a frequency-modulated continuous voltage wave signal electrically connected to said probe and for passing said wave signal to the probe; and
generating reflected wave signals at discontinuities in refractive indices of materials;
c, means in electrical communication with said probe for detecting the resulting frequency differences, and d, means, in electrical communication with said means for detecting frequency differences, for interpreting, recording, and storing said frequency differences, whereby the refractive indices of the interface between materials are measured.
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Abstract
This invention provides apparatus for and a method of locally or remotely monitoring a number of geophysical and other variables related to the refractive index of materials, e.g., soil and pavement moisture content; the moisture content of bulk food products such as grains and beans; liquid levels in storage tanks; interface levels between water and floating layers of oil; the thickness of ice layers; the water/ice interface in partially frozen ground; the location of liquid and gas leaks on roofs, in landfill liners, geosynthetic membranes, and pipelines; and the cables. The detection technique is based on the reflection of frequency-modulated continuous waves during their propagation along transmission line probes embedded in the material being tested.
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Citations
13 Claims
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1. Apparatus for the monitoring of physical variables of an interface between materials related to the refractive indices of such materials comprising
a, a transmission line probe placed in the materials; -
b, means for generating a frequency-modulated continuous voltage wave signal electrically connected to said probe and for passing said wave signal to the probe; and
generating reflected wave signals at discontinuities in refractive indices of materials;
c, means in electrical communication with said probe for detecting the resulting frequency differences, and d, means, in electrical communication with said means for detecting frequency differences, for interpreting, recording, and storing said frequency differences, whereby the refractive indices of the interface between materials are measured. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for monitoring physical variables of an interface between materials related to the refractive indices of such materials comprising
a, placing a transmission line probe within said materials; -
b, generating a frequency-modulated continuous voltage wave signal and passing it to the probe; and
causing a reflected voltage signal to be generated at said interface which marks discontinuities in refractive index of the materials;
c, mixing said reflected signal with the continuous voltage wave signal;
d, detecting frequency difference signals between the continuous voltage wave signal and the reflected signal and e, interpreting, recording, and storing said frequency differences, whereby the refractive indices of the interface between said materials are measured and the desired variables are calculated.
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Specification