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8026731 |
Method and apparatus for constructing images from measurements of impedance
Apparatus and methods are disclosed for obtaining an image of the impedance properties of an object by inferring a measure of straight-line path impedance along a plurality of paths from a...
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7948248 |
Cable length correction
A transmission line impedance compensation method includes the step of providing a measurement device that is adapted to source a test signal having a frequency to a device under test and to...
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7492168 |
Systems and methods for resistivity measurement
Disclosed is a measurement system for measuring subsurface resistivity. The surfaces of interest are, for example, engineered surfaces such as roads and dams, and non-engineered surfaces such as...
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7483735 |
Apparatus and method for monitoring body composition by measuring body dielectric constant and body impedance based on the method of frequency digital sampling
A method for measuring dielectric constant of body endermic tissues and body impedance based on the method of frequency digital sampling and for evaluating body composition is provided, inputting...
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7436188 |
System and method for improving time domain processed sensor signals
Noise discrimination in signals from a plurality of sensors is conducted by enhancing the phase difference in the signals such that off-axis pick-up is suppressed while on-axis pick-up is enhanced....
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7282929 |
Apparatus for current sensing
Apparatus for sensing a current across a known resistor comprising a switched capacitor network and an amplifier having an input coupled to an output of the switched capacitor network. The switched...
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7148694 |
Contact impedance test circuit and method
A contact impedance test circuit for testing impedance between a first contact element and a second contact element comprising an AC signal source for applying an AC signal voltage to the first...
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7019542 |
Method and apparatus for battery testing
A method for testing electrochemical cells applies to a portion of a cycle of a low-frequency excitation waveform to a cell under test while maintaining an amplitude of the excitation waveform...
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6867603 |
Method for measuring high frequency resistance in diesel engine lubrication oil
Soot content in Diesel engine lubrication oil is determined using electrical resistance measurements of the oil at high frequency. A sensor in the form of a capacitor is immersed in the oil,...
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6760633 |
Method and apparatus for predicting stability of a closed loop apparatus
A method for predicting stability of a closed loop apparatus is disclosed. The closed loop apparatus has an open loop impedance and at least one inherent internal gain. The method comprises the...
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6639414 |
Circuit for measuring changes in capacitor gap using a switched capacitor technique
Disclosed is a single-stage, switched capacitor circuit for measuring changes in a variable by measuring changes in a capacitor gap. The change in the capacitor gap corresponds directly to a change...
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6333634 |
Method for measuring radio-frequency current
A radio-frequency power supply (1) and a matching box (2) are electrically connected with a coaxial cable (4) while the matching box (2) and a main unit (3) are electrically connected with a...
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6328934 |
Device for detection of when a test probe gets into contact with a liquid surface
A device for detection of when at test probe of conducting material contacts a liquid surface includes a test probe of conducting material. The test probe is electrically screened by an insulated...
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6278282 |
Method and system for determining oil quality
A method for determining quality of lubricating oil using electrodes in contact with the oil includes applying a potential having a first amplitude to the electrodes, wherein the first amplitude is...
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6054867 |
Method for stabilizing feedback loop of impedance measuring apparatus
A method for stabilizing feedback loop in impedance measuring equipment involves determining a null loop transfer function of the impedance measuring device by utilizing multiple independent, known...
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6037784 |
Resistivity measuring apparatus having transmitter and receiver with power level signals
Material resistivity measuring apparatus includes a transmitter for transmitting a measurement frequency current through the material to a receiver spaced from the transmitter. The transmitter...
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5746905 |
Coating evaluation system
The organic coating deposited on a metallic substrate is quantitatively euated by measurement of electrical signals through an electrochemical cell having an electrode separated from the deposited...
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5668480 |
Variable-phase resistive transducer, and method of operating same
A transducer (23) for producing a digital output signal proportional to a change in a sensed physical parameter includes first and second pairs of series-connected resistors (24, 25 or 26, 28). The...
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5612621 |
Method for monitoring cracks and critical concentration by using phase angle
A method for monitoring cracks in a sample of materials by applying the theory that the phase angle increases in the sample of materials being tested where cracks have formed. The method is...
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5442297 |
Contactless sheet resistance measurement method and apparatus
A contactless sheet resistance measurement apparatus and a method for measuring the sheet resistance of a desired layer of a first conductivity type, formed upon a substrate of an opposite...
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5329238 |
Arrangement for fault monitoring an electric consumer in a motor vehicle to detect short circuits and interruptions in the region of the consumer
The invention is directed to an arrangement for monitoring an electric consumer in a motor vehicle. The consumer can be actuated by at least one pulse-shaped control signal formed by a control unit...
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5138264 |
Apparatus for measuring electrical conductivity
An electrical conductivity measuring apparatus for measuring the electrical conductivity of liquid has a plurality of electrodes disposed in the liquid contained in a measuring cell, with an a.c....
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5093627 |
Impedance and transfer characteristic measuring apparatus
In an impedance and transfer characteristic measuring apparatus sine-wave and cosine-wave data are produced using data obtained by accumulating a fixed phase value in synchronism with a clock...
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5093626 |
Contact measuring device for determining the dry film thickness of a paint on a conductive primer adhered to a plastic substrate
An electrical device for measuring the dry film thickness of a paint film applied to a conductive coating adhered to a plastic substrate without destroying the film; the device contains the...
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4968947 |
Apparatus for the non-destructive measurement of the ohmic resistance of thin layers
The invention concerns apparatus for the non-destructive measurement of the ohmic resistance of thin layers. The apparatus is based on a capacitative measurement process wherein the plates of a...
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4708146 |
Apparatus and method for impedance pneumography
An apparatus and method for monitoring the expansion and contraction of the thoracic cavity during respiration is disclosed. A constant current carrier is passed through the thorax of a patient...
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4656427 |
Liquid conductivity measuring circuit
A liquid conductivity measuring circuit with power-save features is described for use with a four electrode conductivity cell having two potential electrodes and two current electrodes positioned...
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4546310 |
Electrical continuimeter
Electrical continuimeter device for checking the electrical continuity of a conducting layer covering a structure having conducting and non-conducting parts, said conducting layer being covered by...
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4446424 |
Surface resistivimeter
Resistivimeter device for measuring the surface resistance of a structure coated with an inner resistive layer and an outer insulating superficial layer. This device comprises a pick-up to be...
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4372497 |
Method of manufacturing wound items from coaxial microwire and device therefor
A method of manufacturing wound items from coaxial microwire by the use of a device executing said method, which essentially consists in determining frequency f1 of a generator at which a phase...
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4352465 |
Device for manufacturing resistors from insulated wire
A device for manufacturing resistors from insulated wire comprises a mechanism for taking up a wire unwound from a resistor being manufactured, the resistor being installed in a securing mechanism....
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4264860 |
Resistor measuring apparatus
Apparatus for measuring a resistor in function of the amplitude of a direct current or the frequency and the amplitude of an alternating current. When the direct current equipment of this apparatus...
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4209741 |
Apparatus for the continuous monitoring of ground bed resistance
A system for measuring the resistance of an earth electrode such as a coal mine safety ground bed. Current is circulated between the bed and an auxiliary current probe installed approximately ten...
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4200836 |
Apparatus for measuring insulation resistance in an operating three-phase ungrounded transmission line system
By introducing into an operating 3-phase transmission line system through a transformer having the common point of its "Y" or "star" connected primary grounded and its ungrounded secondary coupled...
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4176312 |
Electrical circuitry for measuring low level signals
Electrical circuitry for measuring low level signals comprising a source of ac signals to be measured, a synchronous detector clocked at the frequency of said ac, and a transformer coupling the...
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4175253 |
Analyzing electrical circuit boards
Apparatus for analyzing electrical circuit boards by measuring the voltage drop due test currents flowing along a conductor to an IC mounted on a circuit board, comprising a probe having at least...
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4160205 |
Detection of bacterial activity
Bacterial activity is detected by inoculating the bacteria into a suitable nutrient medium and monitoring the resistive component of the electrical impedance of this culture in such a manner that...
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4148586 |
Apparatus for galvanic detection of optical absorptions
An apparatus and method for utilizing the opto-galvanic effect to perform spectroscopic or analytic investigations of atomic or molecular species. A sample of the substance to be analyzed is...
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4074186 |
Conductivity measuring instrument having linearization means and a digital read-out
Conductivity measuring instruments are provided in which a test coil is supplied with alternating current and a detector responds to the voltage across the test coil to develop an analog voltage...
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4066950 |
Circuit for measuring the ground resistance of an ungrounded power circuit
A measuring circuit for measuring the ground resistance of an ungrounded power circuit, particularly a d-c system supplied from a converter circuit in which a series circuit including an a-c...
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4015209 |
Carrier wave compensator with interference suppression circuit means
A carrier wave compensator includes a novel sampling filter connected between a null amplifier and a compensation potentiometer to suppress interference voltages without deteriorating the dynamic...
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3990066 |
Water quality monitor
An apparatus for monitoring the performance of a reverse osmosis water purification system. The resistivity of the water, and hence its dissolved ionic material concentration, is measured at both...
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3988669 |
Automatic control and detector for three-terminal resistance measurement
A device is provided for automatic control and detection in a three-terminal resistance measuring instrument. The invention is useful for the rapid measurement of the resistivity of various bulk...
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3895292 |
Bridge circuit for measuring resistances
A bridge circuit for measuring resistance of a pair of four-terminal resistances having their current terminals serially connected to an ac source comprising: a voltage follower connectable to each...
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3840804 |
CRYSTAL FREQUENCY MONITOR
Apparatus for broadband measurement and automatic adjustment of piezoelectric-resonator frequencies, based upon phase comparison by means of a quadrature phase detector in an adjustable-phase...
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3792342 |
APPARATUS FOR MEASURING THE RESISTANCE OF A VARIABLE RESISTANCE ELEMENT LOCATED IN A ROTATING BODY
Characteristic features in the apparatus according to the invention mainly consist of improvement of a rotary transformer, a bridge circuit and a detecting means. With these features the...
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3778707 |
MEANS FOR MEASURING LOSS TANGENT OF MATERIAL FOR DETERMINING MOISTURE CONTENT
A-c voltage is applied through two branches to respective input circuits of a phase detector. One of the branches includes a controlled phase shifter and a capacitive impedance circuit; the...
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3769581 |
APPARATUS FOR MEASURING THE DRY UNIT WEIGHT OF A SOIL
Apparatus for measuring the dry unit weight of a soil, either directly or with reference to a known soil variable (e.g., the Proctor density) by means of a measuring probe containing two electrodes...
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3766471 |
METHOD AND APPARATUS FOR DETERMINING MOISTURE CONTENT OF TOBACCO
A method and apparatus for determining the moisture content of freshly prized remoistened tobacco compressed into hogs-heads. An alternating voltage is applied to a pair of electrodes connected in...
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3746975 |
MEASURING CHARACTERISTICS OF MATERIALS BY USING SUSCEPTIVE AND CONDUCTIVE COMPONENTS OF ADMITTANCE
A system for measuring a condition of a material using an admittance probe or probes which are immersed in or placed in proximity to the material, in which both the susceptive and conductive...
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