Abstract: A method and an apparatus is described to measure at least one physical parameter of a substance such as moisture and salt content. This is done by transmitting a microwave beam through the material to be measured and detect only a reflection of a predetermined polarity of the transmitted waves. To accomplish this a polarizing plate is used so that only cross-polarized microwaves, which pass through the substance are detected and the co-polar reflections from surrounding structures are excluded. The object can either be moving as on a conveyer belt or in a rest position.

Abstract: In a method of detecting and eliminating foreign bodies in tobacco, a flow of tobacco advances first through a preparation zone where it is gathered into a continuous ribbon of tobacco filler, then through a forming station at which the filler is used to fashion a continuous cigarette rod, and finally through a cutter device that divides the rod into cigarette sticks; the advancing flow is directed at a given point through a detection device and exposed to electromagnetic radiation of microwave frequency emitted and received in such a way as to generate output signals reflecting any variations in moisture content along the flow of tobacco, caused by the inclusion of foreign bodies and associated with given portions of the flow each coinciding with a singly identifiable cigarette stick.

Abstract: The embodiments of the invention are directed to a new apparatus and method of measuring the water content using time domain reflectometry (TDR), or electrical conductivity in deep soil levels. to. The method uses flat, flexible, waveguides attached to a flexible sleeve filled with a filling material which press the flexible waveguides against an irregularly shaped interior borehole wall.

Abstract: Sensor and process for measuring mass of water on a sheet forming fabric. The sensor includes a microwave element positionable to couple an electromagnetic field into a stock layer to be measured, and a microwave signal generator coupled to the microwave element to generate, in the microwave element, a microwave signal having a frequency lower than a relaxation frequency of water. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

Abstract: Systems and methods for the on-site determination of water content in crude oil. The water content of crude oil is determined by mixing a sample of the crude oil with a fixed amount of molecular sieves. The electromagnetic characteristics of the molecular sieves upon mixing with the sample are then measured and used to determine the water content of the sample. This provides a simple approach to measuring the moisture content in crude oil that is extremely fast, accurate, and reproducible without the use of hazardous chemicals.

Abstract: In a method and apparatus for determining the moisture content of a material with a measuring line extending through the material and having a proximal end connected to a signal generator for supplying a pulse signal to the measuring line, which pulse signal is reflected and returned back to the proximal end of the measuring line to which a comparator is connected for measuring the travel time of the signal supplied, and the reflected signal returned, to the proximal end of the measuring line and its amplitude is with compared with an amplitude corresponding to a threshold, an adjustable threshold value generator and controller are provided generating a threshold value signal which depends on the amplitude of the reflected signal.

Abstract: A method and apparatus for measuring dry density and gravimetric water content of soil includes the steps of providing a plurality of spikes adapted to be driven into the soil and driving the spikes into the soil in spaced relationship. An electrical signal is applied to the spikes and a reflected signal is analyzed using time domain reflectometry to determine an apparent dielectric constant and the bulk electrical conductivity of the soil. With these parameters, the dry density and gravimetric water content of the soil can be calculated using a predetermined relationship between apparent dielectric constant, bulk electrical conductivity, dry density and gravimetric water content. The predetermined relationship includes experimentally determined soil specific calibration constants. The calculated value of the bulk electrical conductivity as determined by time domain reflectometry is adjusted to correspond to a value for which values of the constants are known.

Abstract: In order to measure at least one parameter of a mixture of carrier substance, water and gas, the permittivity value of the mixture is measured at different frequencies by means of a network analyzer (1) and a sensor. The measurements are entered into a mixing formula for forming a system of equations. From the system of equations, at least one parameter of the mixture can be determined. The method is also suited for the measurement of the location dependence of a parameter, e.g. for the measurement of the humidity distribution in concrete.

Abstract: A method and apparatus for detecting soot and/or water concentrations in diesel engine oil having a dielectric constant may include a device for measuring a change in the dielectric constant at a first frequency, a device for measuring a change in the dielectric constant at a second frequency and a processor configured to calculate at least one of a percentage of soot content and a percentage of water content as a function of the measured changes in the dielectric constant at the first and second frequencies. The first frequency may be within approximately the ultrasonic and sub-AM frequency bands and the second frequency may be within approximately the microwave frequency band.

Abstract: The embodiments of the invention are directed to a new apparatus and method of measuring the water content using time domain reflectometry (TDR), or electrical conductivity in deep soil levels to. The method uses flat, flexible, waveguides attached to a flexible sleeve filled with a filling material which press the flexible waveguides against an irregularly shaped interior borehole wall.

Abstract: The invention relates to a method and apparatus for determining the moisture content of bulk material, in particular potting soil, wherein the volume of a quantity of bulk material is determined, the weight of the quantity of bulk material is determined, the specific density is then determined from the volume and the weight, and finally the moisture content is determined by comparison with a table. The invention further relates to a method and apparatus for preparing bulk material, in particular potting soil, with a predetermined moisture content, wherein the volume of a quantity of bulk material is determined, the weight of the quantity of bulk material is determined, and water is then added to the quantity of bulk material until the weight associated with the desired moisture content is obtained.

Abstract: Using surface microwaves for measuring and determining density and/or moisture content of a material. Positioning material within a proximate free space region spanning immediately above surface of a surface microwave waveguide, the surface microwave waveguide includes an electrically conducting rectangular block and a dielectric rectangular insert element compactly fitting into the block. Transmitting microwaves into the first end of the surface microwave waveguide, a first portion of the transmitted microwaves propagate within the surface microwave waveguide and a second portion propagates within the proximate free space region including the material. Parameters (amplitude, phase, attenuation, and phase shift) of the propagating microwaves are perturbed by the material and are a function of density and/or moisture content of the material.

Abstract: A device for testing the quality of rope-like materials in the form of yarns, rollings, fiber bands and the like employs a microwave resonator and devices for determining the displacement of the resonant frequency and the widening of the resonance curve due to the rope-like material present in the microwave resonator. Mechanical devices are provided for transporting the rope-like materials through the measuring volume of the microwave resonator. The microwave field is homogeneous in the measuring volume and the measuring device is a microwave generator constructed for measuring the mass per length and the moisture of the rope-like materials. Sensitivity of the device is improved by using metallic elements to concentrate the electromagnetic field in the measuring volume.

Abstract: A method and apparatus for detecting the concentration of soot particles in engine oil. A microwave signal having a varying frequency is applied to a transmission line having a probe tip exposed to the engine oil. A voltage is read at a stationary detection point along the length of the transmission line for each applied frequency. The applied frequency when the probe voltage is equal to a null voltage of a standing wave within the transmission line is compared to a reference frequency determined when the probe voltage is equal to a null voltage for a known concentration of soot particles. The concentration is calculated based upon the result of the comparison. Preferably, a reference probe receives the same input signal. A known relationship between the reference probe and the transmission line is then used to eliminate temperature effects on the applied frequency.

Abstract: An electrical lead-through bushing with an internal conductor surrounded by an external conductor, extending together through a flange element, is particularly suitable for a TDR (time domain reflectometry) measuring system in which the fill level in a reactor pressure vessel of a nuclear installation is monitored. The bushing is particularly suitable for use on a vessel wherein comparatively high pressures and/or high temperatures may prevail. For this purpose, a first space region, formed on a first side of the flange element between the internal conductor and the external conductor surrounding it, is sealed off with respect to a second space region, formed on a second side of the flange element by the internal conductor and the external conductor surrounding it, by way of a number of sealing rings.

Abstract: A method and apparatus for measuring dry density and gravimetric water content of soil includes the steps of providing a plurality of spikes adapted to be driven into the soil and driving the spikes into the soil in spaced relationship. An electrical signal is applied to the spikes and a reflected signal is analyzed using time domain reflectometry to determine an apparent dielectric constant and the bulk electrical conductivity of the soil. With these parameters, the dry density and gravimetric water content of the soil can be calculated using a predetermined relationship between apparent dielectric constant, bulk electrical conductivity, dry density and gravimetric water content. The predetermined relationship includes experimentally determined soil specific calibration constants. The calculated value of the bulk electrical conductivity as determined by time domain reflectometry is adjusted to correspond to a value for which values of the constants are known.

Abstract: An apparatus for determining the properties of a material, that is to be examined, by applying a swept-frequency high frequency signal and measuring a reflection factor of the resonance signal. The apparatus has a microwave supply conductor for feeding the high frequency signal, a sensor waveguide that is coupled to the microwave supply conductor, a helical conductor that is arranged inside the sensor waveguide, and an intermediate layer between a first end of the sensor waveguide and the helical conductor. Typically, the sensor waveguide is cylindrical and the helical conductor is supported centrally therein along the longitudinal axis of the sensor waveguide by a support that is part of the intermediate layer. A coupling layer is provided between the helical conductor and the material to be examined in the region of a second end face of the sensor waveguide.

Abstract: A method and apparatus for detecting soot and/or water concentrations in diesel engine oil having a dielectric constant may include a device for measuring a change in the dielectric constant at a first frequency, a device for measuring a change in the dielectric constant at a second frequency and a processor configured to calculate at least one of a percentage of soot content and a percentage of water content as a function of the measured changes in the dielectric constant at the first and second frequencies. The first frequency may be within approximately the ultrasonic and sub-AM frequency bands and the second frequency may be within approximately the microwave frequency band.

Abstract: An apparatus and method for monitoring drying of an agricultural porous media such as grain and seed, includes deriving moisture content of the porous media using time domain reflectometry and utilizing moisture content to monitor and/or control the drying process. The porous media is positioned around a time domain reflectometry probe. An array of probes can be used to measure moisture in different areas of one batch of porous media or in a plurality of batches of porous media. The derivation of moisture content of the porous media around each probe would allow information to be provided to a dryer controller to alter the drying process if needed.

Abstract: A level measurement device for measuring the level of material inside of a vessel which includes a conductive element, a signal generating unit, and a receiving unit. The conductive element does not come into direct contact with the material being measured. The signal generating unit generates measurement signals which are transmitted along the conductive element. Each of the measurement signals produces an electromagnetic field which travels along the conductive element and is reflected when it reaches the surface of material in the vessel. The reflected electromagnetic field produces an echo signal which travels along said conductive element to the receiving unit. The receiving unit receives the echo signal and determines the level of material in the vessel. The conductive element can be located outside of the vessel.

Abstract: In order to measure at least one parameter of a mixture of carrier substance, water and gas, the permittivity value of the mixture is measured at different frequencies by means of a network analyzer (1) and a sensor. The measurements are entered into a mixing formula for forming a system of equations. From the system of equations, at least one parameter of the mixture can be determined. The method is also suited for the measurement of the location dependence of a parameter, e.g. for the measurement of the humidity distribution in concrete.

Abstract: A grain moisture sensor is disclosed having a sensor cell that includes a driven plate, a sense plate proximate to and substantially parallel with the driven plate for capacitive measurement across a spacing between the driven plate and the sense plate, and a fill plate adjacent the sense plate and substantially parallel with the driven plate for sensing whether the spacing is filled with grain. Optionally, the sensor cell includes a guard proximate to the parallel to the sense plate such that the sense plate is between the driven plate and the guard. The grain moisture sensor provides for measuring real and imaginary components of an excitation voltage applied to the driven plate, measuring real and imaginary components of a sense current sensed at the sense plate, calculating a complex admittance of the cell, calculating a complex admittance of a reference admittance, and calculating a grain complex permittivity.

Abstract: A continuous flow moisture analyzer (20) determines moisture content in a liquid sample material (46). The moisture analyzer (20) includes an injection system (44) for delivering the liquid sample material (46) at a controlled rate. The injection system includes an injector tube (48). An evaporator (52) has a first end (50) for receiving the injector tube (48) and a second end (56). The injector tube (148) provides the liquid sample material (46) to the evaporator (52) at the first end (50). A carrier gas inlet (54) is in fluid communication with the second end (56) of the evaporator (52) for providing a carrier gas (58) to the evaporator (52) at the second end (56). The carrier gas (58) absorbs moisture from the liquid sample material (46) in the evaporator (52). A relative humidity sensor (78) in fluid communication with the evaporator (52) detects the moisture in the carrier gas (58).

Abstract: Corrosion, mold and moisture can be detected under outer layer of structures, such as surfaces associated with vessels and/or buildings, using nondestructive evaluation (NDE). Characterizing the dielectric properties of materials associated with a target can be executed by directing primary microwave energy from a source towards a target, receiving secondary microwave energy signals returned from the target, analyzing the secondary microwave energy signals, and characterizing dielectric properties of materials associated with the target based on analysis of the secondary signals.

Abstract: A probe adapted for use with a time domain reflectrometry device in primarily measuring the moisture content in soils and other mediums. This probe can however be used in may differing measurement applications involving materials of specific dielectric constants as well as apparent dielectric constants that are derived from a matrix of several differing dielectrics. In the probe according to the present invention, the inner core of the probe is composed of an inner conductive element, a conductor that is used to transmit a broadband pulse. A dielectric liquid, solid or gel surrounds this inner conductive core, and assists in retaining broadband signal strength. The dielectric material is then encased in a metallic outer shell that serves as a protective housing for the probe. This outer shell is electronically transparent to the electromagnetic pulse transmitted by the active inner conductive core and surrounding dielectric.

Abstract: Systems, methods, and probe devices for electronic monitoring and characterization using absorbent media confined by a metallic mesh. The mesh allows a stream of liquid or gas to pass through the structure, so that the media will adsorb the material to which it is specific. This changes the permittivity of the media in which the electromagnetic field is propagating. This change in permittivity can be seen through the use of classical microwave methods such as phase shift, amplitude changes, frequency changes in a cavity or the frequency of an unbuffered oscillator. Some embodiments use a two cylinder structure, where an outer cylinder contains a material which selectively removes a chemical which may be in conflict with or would contaminate the sensing of the desired chemical. This outer cylinder does not play a part in the measurement because it is outside the metal shield which contains the measurement adsorbent, and is thus outside the electromagnetic field.

Abstract: Determinations are made related to the presence of a predetermined material in concrete under test using previously obtained model information. In one embodiment, the predetermined material includes a chloride material and the model information is obtained using a number of cured cement specimens. The model information is stored in memory, such as in the form of a look-up table. When the concrete is being inspected, one or more magnitudes of reflections coefficients are measured and such is utilized with the model information to make determinations related to the presence of the predetermined material. In developing the model information, each of the plurality of cured cement specimens is located in a bath containing the predetermined material. The bath may be pressurized. The cured cement specimens are maintained in the bath for different, known time intervals. After the known time interval for a particular specimen, it is dried and one or more magnitudes of reflection coefficients are measured.

Abstract: A resonant microwave sensor (1) for determining properties of a material (3), that is to be examined, by means of the high-frequency measurement of a reflection factor (r) of a high-frequency resonance signal as measured variable for determining properties of a material to be examined, having

Abstract: The present disclosure is related to an insulation displacement contact (“IDC”) device that transfers electrical contact between two telecommunication cables to complete a media connection. The IDC includes a printed circuit board (“PCB”) which utilizes the positional relationship of a plurality of conductors in communication with the two telecommunication cables to form a capacitance, such that the Near-end Crosstalk (NEXT) and Far End Crosstalk (FEXT) are reduced without compromising impedance.

Abstract: A grain moisture sensor is disclosed having a sensor cell that includes a driven plate, a sense plate proximate to and substantially parallel with the driven plate for capacitive measurement across a spacing between the driven plate and the sense plate, and a fill plate adjacent the sense plate and substantially parallel with the driven plate for sensing whether the spacing is filled with grain. Optionally, the sensor cell includes a guard proximate to the parallel to the sense plate such that the sense plate is between the driven plate and the guard. The grain moisture sensor provides for measuring real and imaginary components of an excitation voltage applied to the driven plate, measuring real and imaginary components of a sense current sensed at the sense plate, calculating a complex admittance of the cell, calculating a complex admittance of a reference admittance, and calculating a grain complex permittivity.

Abstract: The embodiments of the invention are directed to a new apparatus and method of measuring the water content using time domain reflectometry (TDR), or electrical conductivity in deep soil levels. to. The method uses flat, flexible, waveguides attached to a flexible sleeve filled with a filling material which press the flexible waveguides against an irregularly shaped interior borehole wall.

Abstract: A method, software, and system determines temperature of a physical medium using remote measurements. One example of a physical medium is a cloud. A receiver receives at least one first received signal from an interaction of at least one first transmitted electromagnetic signal with the physical medium. A processing system then determines the at least one first received signal information based on the at least one first received signal. The processing system then determines the temperature of the physical medium based on the at least one first received signal information.

Abstract: A propagation-delay-based moisture sensor is disclosed that is capable of providing absolute readings of volumetric water content in a moisture-bearing medium without the need to calibrate the sensor or readings for the conductivity or temperature of the medium. It does so by launching a step transition on a transmission line that is everywhere in contact with the measured medium and that returns the waveform to a high-speed latching comparator wherein the amplitude of the returning waveform is analyzed at precise, programmable time increments. Firmware means in a controlling microprocessor facilitate the successive reconstruction of the significant characteristics of the returning waveform. Analysis of these characteristics by the microprocessor leads to an accurate determination of propagation delay even for severely distorted waveforms. From the propagation delay the moisture content of the medium is derived.

Abstract: A soil moisture measurement system is incorporated in an agricultural implement, for measuring soil moisture during operation of the implement. The soil moisture measurement system includes a sensor or input unit mounted to a subsoil portion of the implement, e.g. to the shank portion of a tillage implement. The soil moisture measurement system may be in the form of a time domain reflectivity (TDR) system. The operator can adjust the depth of the soil-working portion of the implement to attain a desired degree of soil penetration according to soil moisture conditions for seeds to be planted within the soil. Depth adjustment can be accomplished manually by the operator, or automatically by virtue of a depth control unit interconnected with the implement.

Abstract: An apparatus for recognizing road conditions, for use especially in a motor vehicle, includes an infrared transmitter-receiver system. Devices are provided which make it possible to separate signal fractions into different infrared wavelength ranges. This allows for the reliable evaluation of the conditions of the road section being monitored, using a simple and economical device. The infrared devices may be combined with a microwave device.

Abstract: A method and apparatus for time domain reflectometry sensing of moisture in a test material. The sensor (200) having a generally helical shaped electrode (206) and at least one secondary electrode (208) spaced apart from the generally helical shaped electrode (206) to enable the test material to be present in the space (210) between the helical shaped electrode (206) and the secondary electrode (208). A wave pulse generator (202) is coupled to the generally helical shaped electrode (206) and the secondary electrode (208) that results in a reflection of the generated wave from the wave pulse generator (202). Additionally, a reflected pulse detector (204) is coupled to the generally helical shaped electrode (206) and the secondary electrode (208), in which the reflected wave pulse detector (204) receives a reflected wave pulse from the wave pulse generator (202).

Abstract: For transient-current testing of an electronic circuit, a differentiating current measuring device is arranged for measuring an undershoot voltage for each of a series of current pulses controlled in the circuit. In particular, the device is executed in integrated circuit technology and simulates a differentiating current probe. Furthermore, it may have calibration for imparting an offset voltage to each undershoot voltage of the series. This calibrates an actual potential of the simulation and produces for a correct Device Under Test in each cycle a substantially uniform undershoot voltage.

Abstract: This invention provides a method and apparatus for the sensing of moisture using microwave technology. The apparatus provides a wave guide having a linear array of slots in its broadwall. A detector detects reflected energy of microwave signals over a frequency range once the material is positioned over the slots. A value indicative of the power spectral density of the reflected signals is computed and a value for the moisture content of the material determined from the value of power spectral density. The slots are at an angle with respect to the longitudinal axis of the wave guide and the angle can be varied according to the material being tested.

Abstract: A sensor system for use with time domain reflectometry systems to allow measurement of relative proportions of intermixed constituents having differing electrical permittivities contained in a fluid mixture. The sensor has at least one primary electrode and one secondary electrode which are spaced apart across a flow channel. One electrode is connected to a first conductor carrying the active time domain reflectometry signal pulse. The other electrode is connected to the passive or ground conductor which carries any reactive signal resulting from the active signal. A fluid mixture of variable proportions will demonstrate a variable dielectric constant which affects the reflected signals sensed by the time domain reflectometer.

Abstract: In a method and apparatus for determining the volumetric proportion of water in snow and the density of snow, a probe consisting of at least three parallel, but differently spaced, electrical conductors is installed in an area so that the probe is surrounded by the snow, an electromagnetic signal is applied repeatedly to pairs of the conductors for determining different dielectricity coefficients, wherefrom the actual dielectricity coefficient is calculated based on probe-specific calibration data and the measuring steps are repeated with a different frequency for which the dielectricity coefficients of the water and ice are known and the volumetric parts of the snow, that is of the water, ice and air in the snow cover is calculated using the law of mass conservation.

Abstract: An instrument and process for measuring moisture content of an article. A microstrip resonator receives a signal from a microwave sweep oscillator. A holder holds the article wherein the article under test is placed over a substrate of the resonator and covers the resonator and provides orientation to the article under test in a desired direction to the sample. A detector receives transmitted as well as reflected signals from a resonator sensor for measurement of Q factor and frequency shift of the resonator. The moisture content of the article is determined by the change in effective permittivity of a cross-section of the miscorstrip.

Abstract: A method and apparatus for monitoring one or more parameters of a variable physical structure, such as liquid level, is disclosed. The method and apparatus includes an electrodynamic element placed in proximity to a monitored structure and exciting within said element an alternating electromagnetic field. The electromagnetic field should be at a frequency at which the electromagnetic field penetrates into the monitored structure and then variations of the electromagnetic field parameters are measured for the element caused by a variation in the structure. The exciting of the electrodynamic element is by an electromagnetic field in the form of at least one slowed electromagnetic wave having suitable energy distribution of the electric and magnetic fields for the measuring of the electromagnetic field parameters.

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.

Abstract: A sensor system is provided that measures water content or other detectable properties in a medium along the entire length of the sensor at any point in time. The sensor system includes an electromagnetic signal generator and a transmission line disposed in a medium to be monitored. Alternatively, the transmission line can be configured for movement across a medium to be monitored, or the transmission line can be fixed relative to a moving medium being monitored. A signal is transmitted along the transmission line at predetermined frequencies, and the signal is returned back along the transmission line and/or into an optional receive line in proximity to the transmission line. The returned signal is processed to generate a one-dimensional data output profile that is a function of a detectable property of the medium. The data output profile can be mapped onto a physical system to generate a two-dimensional or three-dimensional profile if desired.

Abstract: A method and apparatus for measuring in-place soil density and moisture content. A cylindrical cell is disclosed which may be used to measure the density and the dielectric constant of a soil sample placed within the cylindrical cell. Also disclosed is a multiple rod probe which is designed to contact spikes driven into the ground to measure the in-place dielectric constant of soil. The multiple rod probe includes adjustable studs which ensure complete contact with the spikes. Both measurements are performed using time domain reflectometry. The present invention develops equations for determining the density of the soil in-place from the measured dielectric constant of the soil in-place and the measured density and dielectric constant of the soil in the cylindrical cell.

Abstract: A process for measuring moisture of grains, fruits, nuts and the like (a sample) by connecting the input of a multilayer microstrip hybrid circuit (MMHC) to a pulse generating source, precalibrating the pulse generating source and a time domain reflectometer and connecting the output of the MMHC to a detector. The time domain reflectometer is then calibrated to obtain a characteristic reference reflection and time of propagation through the MMHC is recorded. The sample is placed on the MMHC and a time delay is measured in response to the characteristic reference reflection. The effective permittivity is then calculated based on the parameters of the time domain reflectometer, time delay, reflection coefficient and characteristic impedance of the MMHC. The calculated effective permittivity is then calibrated against moisture.

Abstract: A sensor system for use with time domain reflectometry systems to allow measurement of relative proportions of intermixed constituents having differing electrical permittivities contained in a fluid mixture. The sensor comprises at least one primary electrode and one secondary electrode which are spaced apart across a flow channel. One electrode is connected to a first conductor carrying the active time domain reflectometry signal pulse. The other electrode is connected to the passive or ground conductor which carries any reactive signal resulting from the active signal. A fluid mixture of variable proportions will demonstrate a variable dielectric constant which affects the reflected signals sensed by the time domain reflectometer.

Abstract: A system for measuring the level of the interface between gasoline and water in an underground gasoline storage vessel includes an electronics enclosure from which a transmission line probe extends for contact with the gasoline and water within the vessel. The transmission line probe carries a reflection target disposed at a fixed known position with respect to the electronics enclosure, and at a position normally to be covered by the gasoline. Electronics within the enclosure employ time-domain reflectometry techniques to determine the position or level of the air/liquid surface of the gasoline, and to obtain an apparent position reflection measurement from the target disposed within the gasoline.

Abstract: Time Domain Reflectometry ("TDR") methods and apparatus for measuring propagation velocities of RF pulses to determine material liquid contents, moisture profiles, material levels and dielectric constants including: i) TDR probes and/or probe adaptors, including series averaging probes and multi-segment probes, all employing remotely operable, normally open, variable impedance devices such as diodes; ii) bias insertion and switching networks for rendering selected normally open variable impedance devices conductive one at a time to establish precise unambiguous timing markers T.sub.1 . . . T.sub.

Abstract: An apparatus and method for the moisture content measurement of compressible materials using pressure to firmly hold surface probes against the material to be measured. The apparatus uses moisture measurement circuitry employed in frequency domain impedance or time domain reflectometry devices to obtain moisture content readings from materials. These moisture content readings are based on the apparent dielectric constant of the measured material. Subsurface air voids or gaps found in loose, layered materials undesirably influence moisture measurement readings by reducing the apparent dielectric constant of the measured material. Pressure is supplied through the apparatus to the material in the proximity of the surface probes, thereby reducing air voids to enhance measurement accuracy. The apparatus and method are especially useful for compressible organic materials such as forest duff, hay and soil.