Temperature compensated resonant transmission line sensor
First Claim
1. A position sensing system, comprising:
- a variable frequency signal source coupled to receive a frequency control signal and operable, in response thereto, to supply a radio frequency sensor drive signal at a frequency;
a transmission line sensor having one or more resonant frequencies, the transmission line sensor including a sensor conductor and a moveable dielectric at least partially surrounding the sensor conductor, the sensor conductor having a driven end coupled to receive the sensor drive signal and a terminal end configured to reflect the sensor drive signal to thereby supply a reflected signal to the driven end, the moveable dielectric configured to receive a drive force and, upon receipt thereof, to move the dielectric to a position and thereby vary the one or more resonant frequencies of the transmission sensor; and
a summing and temperature sense circuit including one or more circuit elements having an electrical characteristic that varies with temperature, the summing and temperature sense circuit coupled to receive the radio frequency sensor drive signal and the reflected signal and operable, in response thereto, to supply a standing wave signal having an amplitude that varies with the one or more resonant frequencies of the transmission line sensor, the summing and temperature sense circuit further coupled to receive a direct current sensor excitation signal and operable, in response thereto, to supply a temperature signal representative of transmission line senor temperature.
1 Assignment
0 Petitions
Accused Products
Abstract
A position sensing system uses a resonant transmission line having a moveable dielectric as a position sensor. The system includes circuitry that supplies an RF drive signal to the resonant transmission line, which reflects the drive signal. Based on a standing wave signal, which is generated from the drive signal and the reflected drive signal, the circuitry determines the frequency of the RF sensor drive signal relative to a resonant frequency of the resonant transmission line, and adjusts the RF sensor drive signal frequency to match a resonant frequency of the transmission line. The system additionally includes integral circuitry that senses the temperature of the resonant transmission line and supplies a temperature signal representative thereof. The circuitry determines the relative position of the moveable dielectric based on the adjusted RF sensor drive signal frequency, and supplies a temperature compensated position signal representative thereof.
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Citations
22 Claims
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1. A position sensing system, comprising:
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a variable frequency signal source coupled to receive a frequency control signal and operable, in response thereto, to supply a radio frequency sensor drive signal at a frequency; a transmission line sensor having one or more resonant frequencies, the transmission line sensor including a sensor conductor and a moveable dielectric at least partially surrounding the sensor conductor, the sensor conductor having a driven end coupled to receive the sensor drive signal and a terminal end configured to reflect the sensor drive signal to thereby supply a reflected signal to the driven end, the moveable dielectric configured to receive a drive force and, upon receipt thereof, to move the dielectric to a position and thereby vary the one or more resonant frequencies of the transmission sensor; and a summing and temperature sense circuit including one or more circuit elements having an electrical characteristic that varies with temperature, the summing and temperature sense circuit coupled to receive the radio frequency sensor drive signal and the reflected signal and operable, in response thereto, to supply a standing wave signal having an amplitude that varies with the one or more resonant frequencies of the transmission line sensor, the summing and temperature sense circuit further coupled to receive a direct current sensor excitation signal and operable, in response thereto, to supply a temperature signal representative of transmission line senor temperature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A position sensing system, comprising:
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a variable frequency signal source coupled to receive a frequency control signal and operable, in response thereto, to supply an radio frequency sensor drive signal at a frequency; a direct current power source operable to supply a direct current sensor excitation signal; a transmission line sensor having one or more resonant frequencies, the transmission line sensor including a sensor conductor and a moveable dielectric at least partially surrounding the sensor conductor, the sensor conductor having a driven end coupled to receive the radio frequency sensor drive signal and a terminal end configured to reflect the radio frequency sensor drive signal to thereby supply a reflected signal to the driven end, the moveable dielectric configured to receive a drive force and, upon receipt thereof, to move the dielectric to a position and thereby vary the one or more resonant frequencies of the transmission sensor; and a summing and temperature sense circuit including one or more circuit elements having an electrical characteristic that varies with temperature, the summing and temperature sense circuit coupled to receive the radio frequency sensor drive signal and the reflected signal and operable, in response thereto, to supply a standing wave signal having an amplitude that varies with the one or more resonant frequencies of the transmission line sensor, the summing and temperature sense circuit further coupled to receive the direct current sensor excitation signal and operable, in response thereto, to supply a temperature signal representative of transmission line sensor temperature. - View Dependent Claims (18, 19, 20, 21)
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22. A position sensing system, comprising:
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a variable frequency signal source coupled to receive a frequency control signal and operable, in response thereto, to supply an radio frequency sensor drive signal at a frequency; a direct current power source operable to supply a direct current sensor excitation signal; a transmission line sensor having one or more resonant frequencies, the transmission line sensor including a sensor conductor and a moveable dielectric at least partially surrounding the sensor conductor, the sensor conductor having a driving end coupled to receive the radio frequency sensor drive signal and a terminal end configured to reflect the radio frequency sensor drive signal to thereby supply a reflected signal to the driven end, the moveable dielectric configured to receive a drive force and, upon receipt thereof, to move the dielectric to a position and thereby vary the one or more resonant frequencies of the transmission sensor; a summing and temperature sense circuit including one or more circuit elements having an electrical characteristic that varies with temperature, the summing and temperature sense circuit coupled to receive the radio frequency sensor drive signal and the reflected signal and operable, in response thereto, to supply a standing wave signal having an amplitude that varies with the one or more resonant frequencies of the transmission line sensor, the summing and temperature sense circuit further coupled to receive the direct current sensor excitation signal and operable, in response thereto, to supply a temperature signal representative of transmission line sensor temperature; a control circuit coupled to receive the standing wave signal and operable, in response thereto, to (i) determine the radio frequency sensor drive signal frequency relative to at least one of the transmission line sensor resonant frequencies and (ii) supply the frequency control signal to the variable frequency source, to thereby adjust the radio frequency sensor drive signal frequency to substantially match at least one of the transmission line sensor resonant frequencies; a position determination circuit coupled to receive the adjusted radio frequency sensor drive signal and operable, in response thereto, to determine the position of the moveable dielectric relative to the sensor conductor and supply a position signal representative thereof; and a temperature compensation circuit coupled to receive the temperature signal and the position signal representative of the moveable dielectric relative to the reference conductor and operable, in response thereto, to supply a temperature compensated position signal representative of the position of the moveable dielectric relative to the sensor conductor.
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Specification