US3878723A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermal noise power thermometry
Assignee: United States Atomic Energy Commission
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Filing: 1974-04-15
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Granted: 1975-04-22
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Expires: 1994-04-15
Abstract
Abstract A system for measuring temperature has been provided wherein the absolute temperature Ts is determined by measuring the thermal noise power, i.e., the product of the thermal noise voltage and the thermal noise current generated by a sensing resistor at temperature Ts. The measured thermal noise power from the sensing resistor is a linear function of absolute temperature. The system senses the thermal noise voltage by means of a voltage-sensitive preamplifier and the thermal noise current by means of a currentsensitive preamplifier. The signals from the two preamplifiers are separately detected and stored in separate sample-and-hold circuits after which they are multiplied in a multiplier to obtain an output proportional to the thermal noise power. This means of temperature measurement is independent of the sensingresistor composition, the mass and nature of the charge carriers, and, in principle, the ohmic value of the sensing resistor.
Inventors
- 👤 Theron V Blalock
- 👤 Casimer J Borkowski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:49
CPC Classifications
G; G01; G01K; G01K7/00; G01K7/30
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
224 words
A system for measuring temperature, comprising: a sensing resistor disposed in a medium whose temperature is to be measured; a voltage-sensitive preamplifier for sensing the AC thermal noise voltage generated in said sensing resistor; a current-sensitive preamplifier for sensing the AC thermal noise current generated in said resistor and generating a signal at an output thereof having an amplitude proportional to the thermal noise current; a first switching means for alternately connecting said sensing resistor to the inputs of said voltage-sensitive preamplifier and said current-sensitive preamplifier; an amplifier including a plurality of cascaded passive filters for controlling the system frequency bandpass; a second switching means for alternately connecting the outputs of said voltage-sensitive preamplifier and said current-sensitive preamplifier to said amplifier in sequence with said first switching means; a true root means squared detector means for generating DC output signals proportional to the root mean squared noise signals applied to the input thereof; first and second storage means for storing said DC signals detected from said voltage-sensitive preamplifier and said current-sensitive preamplifier, respectively; and a signal multiplier means responsive to stored DC signals in said first and second storage means for providing an output signal having an amplitude proportional to the product of the detected thermal noise voltage signal and thermal noise current signal, which is indicative of the absolute temperature of said medium.
Claim 2
Independent Claim
224 words
A system for measuring temperature, comprising: a sensing resistor disposed in a medium whose temperature is to be measured; a voltage-sensitive preamplifier for sensing the AC thermal noise voltage generated in said sensing resistor; a current-sensitive preamplifier for sensing the AC thermal noise current generated in said resistor and generating a signal at an output thereof having an amplitude proportional to the thermal noise current; a first switching means for alternately connecting said sensing resistor to the inputs of said voltage-sensitive preamplifier and said current-sensitive preamplifier; an amplifier including a plurality of cascaded passive filters for controlling the system frequency bandpass; a second switching means for alternately connecting the outputs of said voltage-sensitive preamplifier and said current-sensitive preamplifier to said amplifier in sequence with said first switching means; a true root means squared detector means for generating DC output signals proportional to the root mean squared noise signals applied to the input thereof; first and second storage means for storing said DC signals detected from said voltage-sensitive preamplifier and said current-sensitive preamplifier, respectively; and a signal multiplier means responsive to stored DC signals in said first and second storage means for providing an output signal having an amplitude proportional to the product of the detected thermal noise voltage signal and thermal noise current signal, which is indicative of the absolute temperature of said medium.
Claim 3
Independent Claim
224 words
A system for measuring temperature, comprising: a sensing resistor disposed in a medium whose temperature is to be measured; a voltage-sensitive preamplifier for sensing the AC thermal noise voltage generated in said sensing resistor; a current-sensitive preamplifier for sensing the AC thermal noise current generated in said resistor and generating a signal at an output thereof having an amplitude proportional to the thermal noise current; a first switching means for alternately connecting said sensing resistor to the inputs of said voltage-sensitive preamplifier and said current-sensitive preamplifier; an amplifier including a plurality of cascaded passive filters for controlling the system frequency bandpass; a second switching means for alternately connecting the outputs of said voltage-sensitive preamplifier and said currentsensitive preamplifier to said amplifier in sequence with said first switching means; a true root means squared detector means for generating DC output signals proportional to the root mean squared noise signals applied to the input thereof; first and second storage means for storing said DC signals detected from said voltage-sensitive preamplifier and said current-sensitive preamplifier, respectively; and a signal multiplier means responsive to stored DC signals in said first and second storage means for providing an output signal having an amplitude proportional to the product of the detected thermal noise voltage signal and thermal noise current signal, which is indicative of the absolute temperature of said medium.
Claim 4
Independent Claim
224 words
A system for measuring temperature, comprising: a sensing resistor disposed in a medium whose temperature is to be measured; a voltage-sensitive preamplifier for sensing the AC thermal noise voltage generated in said sensing resistor; a current-sensitive preamplifier for sensing the AC thermal noise current generated in said resistor and generating a signal at an output thereof having an amplitude proportional to the thermal noise current; a first switching means for alternately connecting said sensing resistor to the inputs of said voltage-sensitive preamplifier and said current-sensitive preamplifier; an amplifier including a plurality of cascaded passive filters for controlling the system frequency bandpass; a second switching means for alternately connecting the outputs of said voltage-sensitive preamplifier and said currentsensitive preamplifier to said amplifier in sequence with said first switching means; a true root means squared detector means for generating DC output signals proportional to the root mean squared noise signals applied to the input thereof; first and second storage means for storing said DC signals detected from said voltage-sensitive preamplifier and said current-sensitive preamplifier, respectively; and a signal multiplier means responsive to stored DC signals in said first and second storage means for providing an output signal having an amplitude proportional to the product of the detected thermal noise voltage signal and thermal noise current signal, which is indicative of the absolute temperature of said medium.
Claim 5
Dependent Claim
40 words
The temperature measuring system as set forth in claim 1 further including a signal integrator circuit connected in series with the output of said detector means for integrating the DC signals applied thereto to obtain the average DC signal value.
Claim 6
Dependent Claim
26 words
The temperature measuring system as set forth in claim 2 wherein the frequency bandpass of said amplifier is about 40 KHz centered at about 45 KHz.
Claim 7
Dependent Claim
51 words
The temperature measuring system as set forth in claim 2 wherein said first and second storage means include first and second sample-and-hold circuits and a third switching means for alternately connecting the output of said integrator circuit to said first and second sample-and-hold circuits in sequence with said first switching means.
Claim 8
Dependent Claim
124 words
The temperature measuring system as set forth in claim 4 further including a control means having a fixed frequency clock signal source for automatically setting said first, second, and third switching means in a first position to sense said thermal noise voltage and subsequently activating said first sample-and-hold circuit to store the DC signal proportional to said thermal noise voltage signal, alternately setting said first, second, and third switching means in a second position to sense said thermal noise current and subsequently activating said second sample-and-hold circuit to store the DC signal proportional to said thermal noise current and providing a readout signal to said first and second sample-and-hold circuits simultaneously so that said stored DC signals are simultaneously applied to said multiplier means.
Claim 9
Dependent Claim
63 words
The temperature measuring system as set forth in claim 5 wherein said integrator circuit includes a start input and a stop input for receiving control signals from separate outputs of said control means for controlling the time said DC signals are integrated during each of the alternate periods in which said thermal noise voltage signals and said thermal noise current signals are sensed.
Claim 10
Dependent Claim
36 words
The temperature measuring system as set forth in claim 6 further including a voltmeter connected to the output of said multiplier means, said voltmeter being calibrated to read the temperatures of said medium in degrees absolute.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-21 | 1978-10-21 | 1979-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-21 | 1982-10-21 | 1983-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-21 | 1986-10-21 | 1987-04-22 | $7700.00 | Window Closed / Lapsed |