Magnetic field response measurement acquisition system
First Claim
1. A magnetic field response measurement acquisition system, comprising:
- one or more inductively powered magnetic field response sensors, wherein one or more attributes of the one or more sensor responses correspond to one or more measured unrelated physical states and further wherein said one or more attributes are selected from the group consisting of amplitude, frequency and bandwidth;
antenna means for transmitting magnetic fields to power said one or more sensors and for receiving magnetic field responses from said one or more sensors;
an interrogation means for regulating said magnetic field transmission from and reception to said antenna means, and for analyzing said one or more sensor response attributes received from said one or more sensors, wherein said interrogation means can interrogate multiple sensors concurrently using a single acquisition channel, does not require that said signals from said one or more sensors be transmitted as modulated signals on a radio frequency carrier, and can concurrently acquire measurements of more than one unrelated physical state from each said sensor.
2 Assignments
0 Petitions
Accused Products
Abstract
Magnetic field response sensors designed as passive inductor-capacitor circuits produce magnetic field responses whose harmonic frequencies correspond to states of physical properties for which the sensors measure. Power to the sensing element is acquired using Faraday induction. A radio frequency antenna produces the time varying magnetic field used for powering the sensor, as well as receiving the magnetic field response of the sensor. An interrogation architecture for discerning changes in sensor'"'"'s response frequency, resistance and amplitude is integral to the method thus enabling a variety of measurements. Multiple sensors can be interrogated using this method, thus eliminating the need to have a data acquisition channel dedicated to each sensor. The method does not require the sensors to be in proximity to any form of acquisition hardware. A vast array of sensors can be used as interchangeable parts in an overall sensing system.
94 Citations
52 Claims
-
1. A magnetic field response measurement acquisition system, comprising:
-
one or more inductively powered magnetic field response sensors, wherein one or more attributes of the one or more sensor responses correspond to one or more measured unrelated physical states and further wherein said one or more attributes are selected from the group consisting of amplitude, frequency and bandwidth; antenna means for transmitting magnetic fields to power said one or more sensors and for receiving magnetic field responses from said one or more sensors; an interrogation means for regulating said magnetic field transmission from and reception to said antenna means, and for analyzing said one or more sensor response attributes received from said one or more sensors, wherein said interrogation means can interrogate multiple sensors concurrently using a single acquisition channel, does not require that said signals from said one or more sensors be transmitted as modulated signals on a radio frequency carrier, and can concurrently acquire measurements of more than one unrelated physical state from each said sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
-
-
28. A magnetic field response measurement acquisition system, comprising:
-
one or more inductively powered magnetic field response sensors, wherein one or more attributes of the one or more sensor responses correspond to one or more measured unrelated physical states and further wherein said one or more attributes are selected from the group consisting of amplitude, frequency and bandwidth; antenna means for transmitting magnetic fields to power said one or more sensors and for receiving magnetic field responses from said one or more sensors; an interrogation means for regulating said magnetic field transmission from and reception to said antenna means, and for analyzing said one or more sensor response attributes received from said one or more sensors, wherein said interrogation means can interrogate multiple sensors concurrently using a single acquisition channel, does not require that said signals from said one or more sensors be transmitted as modulated signals on a radio frequency carrier, and can concurrently acquire measurements of more than one unrelated physical state from each said sensor; wherein said antenna means is a single switching antenna, and further wherein said interrogation means comprises the following steps; (a) at the lower limit of a predetermined range, transmitting a radio frequency harmonic for a predetermined length of time from said antenna; (b) switching said transmission mode of said antenna off; (c) turning the receiving mode of said antenna on; (d) rectifying the received response from said sensor to determine its amplitude; (e) storing the amplitude, Ai(t), of said rectified response and the frequency, ω
i(t), of said transmitted radio frequency harmonic;(f) switching the receiving mode off and the transmission mode on; (g) shifting the transmitted radio frequency harmonic by a predetermined amount; (h) transmitting the harmonic for a predetermined length of time; (i) switching the transmission mode off; (j) switching the receiving mode on; (k) rectifying the received response from said sensor to determine its amplitude; (1) storing said current amplitude, Ai, and said frequency, ω
i;(m) comparing said amplitude, Ai, to the two previously recorded amplitudes, Ai−
1 and Ai−
2;(n) if said previous amplitude, Ai−
1, is greater than said amplitude, Ai, and the previous amplitude, Ai−
1, is greater than the amplitude prior to it, Ai−
2, storing said amplitude, Ai−
1, as the amplitude inflection and the corresponding frequency, ω
i−
1, for the current frequency sweep;(o) comparing said amplitudes obtained in step (n) with the amplitudes of the next subsequent sweep; (p) repeating steps (f) through (l) if an amplitude inflection has not been reached; and (q) once amplitude inflection has been reached, continuing the sweep to said next sensor. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37)
-
-
38. A magnetic field response measurement acquisition system, comprising:
-
one or more inductively powered magnetic field response sensors, wherein one or more attributes of the one or more sensor responses correspond to one or more measured unrelated physical states and further wherein said one or more attributes are selected from the group consisting of amplitude, frequency and bandwidth; antenna means for transmitting magnetic fields to power said one or more sensors and for receiving magnetic field responses from said one or more sensors; an interrogation means for regulating said magnetic field transmission from and reception to said antenna means, and for analyzing said one or more sensor response attributes received from said one or more sensors, wherein said interrogation means can interrogate multiple sensors concurrently using a single acquisition channel, does not require that said signals from said one or more sensors be transmitted as modulated signals on a radio frequency carrier, and can concurrently acquire measurements of more than one unrelated physical state from each said sensor; wherein said antenna means is separate transmission and receiving antennae; and
further wberein said interrogation means comprises the following steps;(a) at the lower limit of a predetermined range, transmitting a radio frequency harmonic for a predetermined length of time from said antenna; (b) turning said transmission antenna; (c) turning said receiving antenna on; (d) rectifying the received response from said sensor to determine its amplitude; (e) storing the amplitude, Ai(t), of said rectified response and the frequency, ω
i(t), of said transmitted radio frequency harmonic;(f) turning said receiving antenna off and transmission antenna on; (g) shifting the transmitted radio frequency harmonic by a predetermined amount; (h) transmitting the harmonic for a predetermined length of time; (i) turning said transmission antenna off; (j) turning said receiving antenna on; (k) rectifying the received response from said sensor to determine its amplitude; (l) storing said current amplitude, Ai, and said frequency ω
i;(m) comparing said amplitude, Ai, to the two previously recorded amplitudes, Ai−
1 and Ai−
2;(n) if said previous amplitude, Ai−
1, is greater than said amplitude, Ai, and the previous amplitude, Ai−
1, is greater than the amplitude prior to it, Ai−
2, storing said amplitude, Ai−
1, as the amplitude inflection and the corresponding frequency, ω
i−
1, for the current frequency sweep;(o) comparing said amplitudes obtained in step (n) with the amplitudes of the next subsequent sweep; (p) repeating steps (f) through (l) if an amplitude inflection has not been reached; and (q) once amplitude inflection has been reached, continuing the sweep to said next sensor. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46, 49)
-
-
47. A magnetic field response measurement acquisition system, comprising:
-
one or more inductively powered magnetic field response sensors, wherein one or more attributes of the one or more sensor responses correspond to one or more measured unrelated physical states and further wherein said one or more attributes are selected from the group consisting of amplitude, frequency and bandwidth; antenna means for transmitting magnetic fields to power said one or more sensors and for receiving magnetic field responses from said one or more sensors; an interrogation means for regulating said magnetic field transmission from and reception to said antenna means, and for analyzing said one or more sensor response attributes received from said one or more sensors, wherein said interrogation means can interrogate multiple sensors concurrently using a single acquisition channel, does not require that said signals from said one or more sensors be transmitted as modulated signals on a radio frequency carrier, and can concurrently acquire measurements of more than one unrelated physical state from each said sensor, wherein said interrogation means comprises; an antenna for transmitting and receiving a varying magnetic field; a microcontroller that places said antenna into transmission mode and submits a binary code to a frequency synthesizer, said frequency synthesizer concerting said code into a square wave with the frequency of the wave dependent on said binary code; a high-speed amplifier that amplifies said square wave; a low pass filter that attenuates all frequencies that are higher than a prescribed frequency for application to said antenna for a prescribed number of cycles; applying said low pass filter signal to said antenna for a prescribed number of cycles; a radio frequency receiving/transmission switch for switching said antenna to receiving mode; a high speed amplifier that amplifies the signal from said sensor after it is received from said antenna; a diode peak detector that rectifies said amplified signal and creates a DC value proportional to signal amplitude; an op amp that amplifies said DC voltage from said peak detector; an analog to digital converter that converts said signal from said op amp to a digital signal; and said microcontroller storing the amplitude of digital signal and the transmission frequency. - View Dependent Claims (48)
-
-
50. A magnetic field response measurement acquisition system, comprising:
-
one or more inductively powered magnetic field response sensors, wherein one or more attributes of the one or more sensor responses correspond to one or more measured unrelated physical states and further wherein said one or more attributes are selected from the group consisting of amplitude, frequency and bandwidth; antenna means for transmitting magnetic fields to power said one or more sensors and for receiving magnetic field responses from said one or more sensors; an interrogation means for regulating said magnetic field transmission from and reception to said antenna means, and for analyzing said one or more sensor response attributes received from said one or more sensors, wherein said interrogation means can interrogate multiple sensors concurrently using a single acquisition channel, does not require that said signals from said one or more sensors be transmitted as modulated signals on a radio frequency carrier, and can concurrently acquire measurements of more than one unrelated physical state from each said sensor; wherein at least one said sensor is mounted to a conductive surface, further wherein said sensor has an inductor that has a fixed separation from said conductive surface.
-
-
51. A magnetic field response measurement acquisition system, comprising:
-
one or more inductively powered magnetic field response sensors, wherein one or more attributes of the one or more sensor responses correspond to one or more measured unrelated physical states and further wherein said one or more attributes are selected from the group consisting of amplitude, frequency and bandwidth; antenna means for transmitting magnetic fields to power said one or more sensors and for receiving magnetic field responses from said one or more sensors; an interrogation means for regulating said magnetic field transmission from and reception to said antenna means, and for analyzing said one or more sensor response attributes received from said one or more sensors, wherein said interrogation means can interrogate multiple sensors concurrently using a single acquisition channel, does not require that said signals from said one or more sensors be transmitted as modulated signals on a radio frequency carrier, and can concurrently acquire measurements of more than one unrelated physical state from each said sensor; wherein at least one said sensor measures a physical state within a conductive cavity, further wherein the inductor of said sensor is mounted external to said cavity at a fixed distance and fixed orientation from said cavity wall, the capacitor of said sensor is mounted internal to said cavity, and said antenna is mounted external to said cavity.
-
-
52. A magnetic field response measurement acquisition system, comprising:
-
one or more inductively powered magnetic field response sensors, wherein one or more attributes of the one or more sensor responses correspond to one or more measured unrelated physical states and further wherein said one or more attributes are selected from the group consistng of amplitude, frequency and bandwidth; antenna means for transmitting magnetic fields to power said one or more sensors and for receiving magnetic field responses from said one or more sensors; an interrogation means for regulating said magnetic field transmission from and reception to said antenna means, and for analyzing said one or more sensor response attributes received from said one or more sensors, wherein said interrogation means can interrogate multiple sensors concurrently using a single acquisition channel, does not require that said signals from said one or more sensors be transmitted as modulated signals on a radio frequency carrier, and can concurrently acquire measurements of more than one unrelated physical state from each said sensor; wherein multiple sensors measure multiple physical states within a conductive cavity, further wherein said inductors of said sensors are mounted external to said cavity at distances and fixed orientations from said cavity wall, said capacitors of said sensors are mounted internal to said cavity, and said antenna is mounted internal to said cavity.
-
Specification