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WO2024196962A1 - Radiomètre à micro-ondes avec détection d'interférence et procédés associés - Google Patents

Radiomètre à micro-ondes avec détection d'interférence et procédés associés Download PDF

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Publication number
WO2024196962A1
WO2024196962A1 PCT/US2024/020600 US2024020600W WO2024196962A1 WO 2024196962 A1 WO2024196962 A1 WO 2024196962A1 US 2024020600 W US2024020600 W US 2024020600W WO 2024196962 A1 WO2024196962 A1 WO 2024196962A1
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WIPO (PCT)
Prior art keywords
signal
temperature
phase
microwave
quadrature
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PCT/US2024/020600
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English (en)
Inventor
Zorana Popovic
Gabriel Santamaria BOTELLO
Jooeun LEE
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University of Colorado System
University of Colorado Colorado Springs
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University of Colorado System
University of Colorado Colorado Springs
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Publication of WO2024196962A1 publication Critical patent/WO2024196962A1/fr
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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
    • G01K11/006—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using measurement of the effect of a material on microwaves or longer electromagnetic waves, e.g. measuring temperature via microwaves emitted by the object
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/01—Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue
    • A61B5/015—By temperature mapping of body part
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
    • A61B5/0507—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves using microwaves or terahertz waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K13/00—Thermometers specially adapted for specific purposes
    • G01K13/20—Clinical contact thermometers for use with humans or animals
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2560/00—Constructional details of operational features of apparatus; Accessories for medical measuring apparatus
    • A61B2560/02—Operational features
    • A61B2560/0242—Operational features adapted to measure environmental factors, e.g. temperature, pollution
    • A61B2560/0247—Operational features adapted to measure environmental factors, e.g. temperature, pollution for compensation or correction of the measured physiological value
    • A61B2560/0252—Operational features adapted to measure environmental factors, e.g. temperature, pollution for compensation or correction of the measured physiological value using ambient temperature

Definitions

  • a microwave radiometer uses a high-sensitivity receiver to measure thermal radiation, as detected by a microwave probe connected to the receiver’s input.
  • the thermal radiation typically lies within the microwave region of the electromagnetic spectrum (e.g., 0.3 to 300 GHz). By measuring the radiant flux of this thermal radiation at different frequencies, the microwave radiometer can estimate the spectrum of the thermal radiation. This spectrum may be used to determine the temperature of a blackbody source emitting the thermal radiation.
  • the present embodiments include microwave radiometers, and associated radiometry methods, that are optimized for non-invasive temperature measurements of internal tissue layers in human beings and other animals.
  • Medical conditions that present as an change in core temperature include, but are not limited to, hyperthermia (e.g., heat exhaustion, heat stress, heatstroke, etc.), hypothermia, endocrine disorders (e.g., hypothyroidism, hyperthyroidism), central nervous system disorders, and the disruption of thermoregulation caused by certain medications (e.g., nonsteroidal anti-inflammatory drugs, or NSAIDs).
  • hyperthermia e.g., heat exhaustion, heat stress, heatstroke, etc.
  • hypothermia e.g., endocrine disorders (e.g., hypothyroidism, hyperthyroidism), central nervous system disorders, and the disruption of thermoregulation caused by certain medications (e.g., nonsteroidal anti-inflammatory drugs, or NSAIDs).
  • hyperthermia for cancer treatment is performed by increasing the core temperature of the body to temperatures up to 44°C (approximately 111°F).
  • microwave probe is placed on the subject’s skin.
  • the term “probe” is used herein to refer to a device, typically a circuit element, that converts electromagnetic radiation into an electrical signal. Microwave probes differ from antennas in that they are typically used with sources that are physically located within the near-field region. Note that the term “probe” is not used herein in the medical context, i.e., as a device used for invasive measurements of a subject.
  • microwave thermometry may be non-invasive.
  • Many of the present embodiments advantageous identify radio-frequency interference (RFI) picked up by the microwave probe. This RFI contaminates the input signal processed by the radiometer, skewing the resulting temperature measurement.
  • the radiometer may implement any of several techniques to prevent this RFI from affecting the accuracy of the determined radiometric temperature. For example, the radiometer may select a different frequency band to measure, one that does not contain the RFI. In other embodiments, the radiometer may process the input signal to remove the RFI, thereby ensuring that only noise is used to determine the radiometric temperature. The radiometer may also record which frequency bands have RFI.
  • a method for microwave radiometry includes receiving, by a microwave probe, thermal radiation emitted by a sample. The method also includes amplifying an output of the microwave probe to generate an amplified signal, demodulating the amplified Client Ref. CU5891B-PCT1 Attorney Docket No.
  • a microwave radiometer includes a front-end amplifier, a local oscillator, a demodulator, a correlator, a detector, and a signal processor.
  • the demodulator has a signal-input port connected to an output of the front-end amplifier, a local- oscillator port connected to an output of the local oscillator, an in-phase output port, and a quadrature output port.
  • the correlator is configured to process in-phase and quadrature signals from the in-phase and quadrature output ports to generate a cross-correlation signal.
  • the detector is configured to detect one or both of the in-phase and quadrature signals to generate a temperature signal.
  • the signal processor is configured to process the temperature signal to at least partly determine a radiometric temperature.
  • the signal processor is also configured to output the radiometric temperature if the cross-correlation signal is less than a threshold.
  • FIG. 1 shows a thermometer that uses near-field microwave radiometry to measure one or more temperatures of a tissue stack of a patient, in embodiments.
  • FIG.2A is a schematic diagram of a signal-processing circuit that processes an input waveform ⁇ ( ⁇ ) to determine the cross-correlation of I and Q components of the input waveform ⁇ ( ⁇ ), in embodiments.
  • FIG.2B is a spectrum illustrating how the signal-processing circuit of FIG.2A processes spectral components of the input waveform ⁇ ( ⁇ ).
  • FIG. 3A shows the signal-processing circuit of FIG. 2A processing an input waveform ⁇ ( ⁇ ) that is coherent, in embodiments.
  • FIG.3B is a spectrum of the coherent input waveform ⁇ ( ⁇ ) shown in FIG.3A.
  • FIG. 4A shows the signal-processing circuit of FIG. 2A processing an input waveform ⁇ ( ⁇ ) that contains both thermal noise and a coherent signal (e.g., interference).
  • FIG.4B is a spectrum of the input waveform ⁇ ( ⁇ ) shown in FIG.4A.
  • FIG.5 is a plot of cross-correlation coefficient ⁇ as a function of frequency ⁇ .
  • FIG. 6 is a schematic diagram of a radiometer with interference detection, in embodiments. Client Ref. CU5891B-PCT1 Attorney Docket No.
  • FIG. 7 is a schematic diagram of a radiometer with interference detection, in embodiments.
  • FIG.8 is a schematic diagram of a radiometer that performs noise calibration, in embodiments.
  • FIG. 9 is a schematic diagram of a radiometer that implements frequency- domain reflectometry, in embodiments.
  • FIG. 10 is a schematic diagram of a radiometer that implements white-noise reflectometry, in embodiments. DETAILED DESCRIPTION
  • FIG.1 shows a thermometer 100 that uses near-field microwave radiometry to measure one or more temperatures of a tissue stack 104 of a patient.
  • the tissue stack 104 includes a layer of skin tissue 110, a layer of fat tissue 112, a layer of bone tissue 114, and a layer of organ tissue 116.
  • the thermometer 100 includes a sensor head 120 that is placed in physical contact with the skin tissue 110, outside of the patient’s body.
  • the sensor head 120 includes a microwave probe 124 that receives thermal radiation emitted by the tissue stack 104.
  • Layers of the tissue stack 104 closer to, and including, the skin tissue 110 are partially transmissive to microwaves, thereby allowing thermal radiation emitted from deeper tissue layers (e.g., the organ tissue 116) to reach and pass through the skin tissue 110 to exit the tissue stack 104 and therefore the patient’s body.
  • the microwave probe 124 converts thermal radiation exiting the tissue into an electrical signal that is conducted to a radiometer 102 via a transmission line 106.
  • the internal temperature of a person varies depending on the type of tissue, its depth from the skin tissue 110, and its location within the body (e.g., based on its proximity to organs that generate heat or fluids that thermally conduct heat away).
  • the tissue layers in FIG.1 may have different temperatures. For clarity in FIG.
  • each of these tissue layers has a uniform temperature, i.e., the layer of skin tissue 110 has a uniform skin temperature ⁇ ⁇ , the layer of fat tissue 112 has a uniform fat temperature ⁇ ⁇ , the layer of bone tissue 114 has a uniform bone temperature ⁇ ⁇ , and the layer of organ tissue 116 has a uniform organ temperature ⁇ ⁇ .
  • the output of the microwave probe 124 is received by the radiometer 102, via the transmission line 106, as an input signal 136.
  • the radiometer 102 processes the input signal 136 to determine a radiometric temperature 130. As shown in FIG.1, the radiometer 102 outputs the radiometric temperature 130.
  • the radiometric temperature 130 may be Client Ref.
  • the radiometric temperature 130 may be transmitted (e.g., via Wi-Fi or Bluetooth) to a computer system that stores the radiometric temperature 130 (e.g., in a medical record of the patient).
  • the sensor head 120 includes a temperature sensor 126 that measures the skin temperature ⁇ ⁇ .
  • the temperature sensor 126 may be an electrical temperature sensor, such as a thermistor, thermocouple, or bandgap temperature sensor.
  • the temperature sensor 126 may be an integrated-circuit (IC) temperature transducer.
  • the temperature sensor 126 may be an infrared detector.
  • the temperature sensor 126 is electrically connected to the radiometer 102 via a cable 108.
  • the radiometer 102 may use the skin temperature ⁇ ⁇ , as determined by the temperature sensor 126, to help determine the temperatures of tissue layers deeper in the tissue stack 104.
  • a medical worker e.g., doctor, nurse, etc.
  • the radiometric temperature 130 may be used to not only identify a patient as being ill, but also to determine if the patient is not ill.
  • the medical worker may then provide a therapeutic intervention, if needed.
  • a therapeutic intervention e.g., if the medical worker diagnoses the patient as having a disease, he or she may prescribe, provide, or perform a therapeutic intervention for treating the disease.
  • the medical worker may use additional information to decide on the therapeutic intervention (e.g., age, gender, blood pressure, temperature, etc.).
  • therapeutic interventions include, but are not limited to, surgical procedures, non- surgical medical procedures, and prescriptions for one or more pharmaceutical drugs.
  • the layers of the tissue stack 104 shown in FIG. 1 are examples of types of tissues whose temperatures may be measured with the thermometer 100.
  • the tissue stack 104 may include additional or alternative types of tissues.
  • FIG.1 shows the tissue stack 104 with four layers
  • the tissue stack 104 may contain more or fewer layers.
  • the patient may be a human being or another type of animal (e.g., a pet or farm animal).
  • the radiometer 102 is similar to other radiometers known in the art except that it identifies interference that is received by the microwave probe 124 and therefore contaminates the input signal 136. If the radiometer 102 determines that interference is present, it may implement any of several techniques to prevent the interference from affecting the accuracy of the radiometric temperature 130. For example, the radiometer 102 may select a different frequency band to measure, one that does not contain the interference. In another Client Ref. CU5891B-PCT1 Attorney Docket No.
  • the radiometer 102 may process the input signal 136 to remove the interference, thereby ensuring that only noise is used to determine the radiometric temperature 130.
  • the radiometer 102 may also record which frequency bands have interference. These bands are referred to as “contaminated” while bands in which no interference was found are referred to as “interference-free” or “clean.” By making note of which bands are contaminated and clean, the radiometer 102 may be configured to avoid future measurements in contaminated bands, instead focusing on clean bands.
  • the radiometers of the present embodiments may operate over broad frequency ranges (i.e., several gigahertz, or more). In general, tissue layers emit detectable levels of thermal radiation across a broad span of the electromagnetic spectrum.
  • the radiometric temperature 130 may be used as an input to a tissue-stack model that characterizes the temperature distribution of the tissue stack 104.
  • tissue-stack model that characterizes the temperature distribution of the tissue stack 104.
  • United States Patent No. 10,506,930 which is incorporated herein by reference, describes one such tissue-stack model in which the radiometric temperature 130 is a weighted sum of temperatures of the layers of the tissue stack 104.
  • radiometric temperatures 130 at different frequency bands may be used to fully constrain the tissue-stack model, thereby uniquely determining a temperature for each of the layers in the tissue stack 104.
  • the mathematical inversion of the tissue-stack model may be performed by the present embodiments (e.g., the signal processor 720 of FIG. 7). Alternatively, several radiometric temperatures 130 may be transmitted to an external computing device that performs the inversion.
  • the present embodiments utilize the fact that noise and coherent signals have different statistical properties. Therefore, these statistical properties may be used to determine whether a signal (e.g., the input signal 136 in FIG.1) is primarily noise, a coherent signal (i.e., interference), or a combination thereof.
  • the thermal noise in the time domain, may be mathematically represented as Assuming that th interfering signal has a frequency at a different in-band frequency where
  • P2049WO/00604329 Eqn.11 shows how the interfering signal appears as a non-zero cross-correlation of the I and Q outputs when ⁇ ( ⁇ ) ⁇ ⁇ ⁇ /2 (i.e., ⁇ ⁇ 0).
  • the presence of the interfering signal may be determined, for example, by searching for the maximum value of ⁇ ⁇ ( ⁇ ) for different values of ⁇ . The maximum value may then be compared to a threshold. If the maximum value exceeds the threshold, then an interfering signal within the bandwidth ⁇ ⁇ is present. Otherwise, no interfering signal is present.
  • FIG.2A is a schematic diagram of a signal-processing circuit 200 that processes an input waveform ⁇ ( ⁇ ) to determine the cross-correlation ⁇ ⁇ ( ⁇ ) of I and Q components of the input waveform ⁇ ( ⁇ ).
  • the circuit 200 includes an IQ demodulator 202 with a signal input port “SIG”, a local oscillator input port “LO”, an in-phase output port “I” and a quadrature output port “Q”.
  • the signal input port is driven by a local oscillator (LO) 204 that outputs a sinusoidal signal having an LO frequency ⁇ ⁇ .
  • LO local oscillator
  • the IQ demodulator 202 After down-converting to baseband, the IQ demodulator 202 simultaneously outputs a time-varying in-phase waveform ⁇ ( ⁇ ) from the in-phase output port I and a time-varying quadrature waveform ⁇ ( ⁇ ) from the quadrature output port Q.
  • the circuit 200 includes a low-pass filter 206 filters the in-phase waveform ⁇ ( ⁇ ) into a filtered in- phase waveform ⁇ ⁇ ⁇ ( ⁇ ) and a low-pass filter 208 that filters the quadrature waveform ⁇ ( ⁇ ) into a filtered quadrature waveform ⁇ ⁇ ⁇ ( ⁇ ). It is assumed that the low-pass filters 206 and 208 have the same cut-off frequency ⁇ ⁇ ⁇ and that the cut-off frequency ⁇ ⁇ ⁇ is low enough to effectively filter any spectral component at 2 ⁇ ⁇ .
  • the signal-processing circuit 200 also includes a correlator 210 that processes the filtered waveforms ⁇ ⁇ ⁇ ( ⁇ ) and ⁇ ⁇ ⁇ ( ⁇ ) to determine the cross-correlation ⁇ ( ⁇ ) therebetween for various values of the time lag ⁇ .
  • the correlator 210 may then determine the maximum value of the cross-correlation and output this maximum value as a cross-correlation coefficient ⁇ .
  • Client Ref. CU5891B-PCT1 Attorney Docket No. P2049WO/00604329 [0036]
  • the input waveform ⁇ ( ⁇ ) consists of only white noise.
  • the filtered signals ⁇ ⁇ ⁇ ( ⁇ ) and ⁇ ⁇ ⁇ ( ⁇ ) have no cross-correlation, i.e., the cross-correlation coefficient ⁇ is zero. Due to the finite duration of the input waveform ⁇ ( ⁇ ) and discrete sampling, the cross- correlation coefficient ⁇ will be close to zero, but not exactly zero.
  • FIG. 2B is a spectrum illustrating how the signal-processing circuit 200 only processes spectral components of the input waveform ⁇ ( ⁇ ) that lie within a frequency band 228, or channel, that is centered at the LO frequency ⁇ and has a bandwidth of approximately 2 ⁇ ⁇ .
  • the input waveform ⁇ ( ⁇ ) is assumed to be noise, corresponding to FIG. 2A.
  • FIG.3A shows the signal-processing circuit 200 processing an input waveform ⁇ ( ⁇ ) that is coherent.
  • the input waveform ⁇ ( ⁇ ) is sinusoidal with a frequency ⁇ ⁇ .
  • FIG. 3B it is assumed that the frequency lies within the frequency band 228.
  • FIG.4A shows the signal-processing circuit 200 processing an input waveform ⁇ ( ⁇ ) that contains both thermal noise and a coherent signal (e.g., interference).
  • the filtered signals ⁇ ⁇ ⁇ ( ⁇ ) and ⁇ ⁇ ⁇ ( ⁇ ) are partially correlated, i.e., the cross-correlation coefficient ⁇ has a magnitude greater than 0 and less than 1.
  • some of the thermal noise and coherent signal may lie within the frequency band 228.
  • FIG.5 is a plot of the cross-correlation coefficient ⁇ as a function of frequency ⁇ .
  • FIG.5 shows how the signal-processing circuit 200 may be used to identify clean frequency spans that are greater than 2 ⁇ ⁇ ⁇ . As described in more detail below, large frequency spans that are clean are ideal for quickly acquiring temperature data.
  • the LO frequency is changed such that the circuit 200 processes a different frequency band. All of the frequency bands have the same bandwidth 2 ⁇ ⁇ ⁇ .
  • the cross-correlation coefficient ⁇ was measured for 11 different bands (i.e., 11 different values of the LO frequency). Each band is identified by its center Client Ref.
  • CU5891B-PCT1 Attorney Docket No. P2049WO/00604329 frequency ⁇ ⁇ , where 1 ⁇ ⁇ ⁇ 11.
  • the first six bands are clean given their low values of ⁇ . This indicates that the entire frequency span from ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ to ⁇ ⁇ + ⁇ ⁇ ⁇ is clean and therefore usable for radiometric temperature measurements. The same is true for the bands centered at frequencies ⁇ , ⁇ ⁇ , ⁇ ⁇ , and ⁇ ⁇ . However, the band centered at frequency ⁇ ⁇ has a much larger value of ⁇ , a clear indication that this band is contaminated and should not be used for temperature measurements.
  • FIG.6 is a schematic diagram of a radiometer 600 with interference detection.
  • the radiometer 600 includes a front-end amplifier 602 that amplifies the input signal 136, as received from the microwave probe 124 via the transmission line 106 (see FIG. 1), into an amplified signal 632.
  • a splitter 604 splits the amplified signal 632 into a first split signal 634 and a second split signal 636.
  • a first mixer 606 down-converts the first split signal 634 to baseband using an LO signal 638 generated by an LO 618.
  • the output of the first mixer 606 is a first baseband signal 640.
  • a first low-pass filter 610 with cut-off frequency ⁇ ⁇ ⁇ filters the first baseband signal 640 into a first filtered signal 644.
  • a first analog-to-digital converter (ADC) 614 then digitizes the first filtered signal 644 to generate a first digital waveform 648.
  • ADC analog-to-digital converter
  • a second mixer 608 down-converts the second split signal 636 to baseband using the LO signal 638.
  • the output of the second mixer 608 is a second baseband signal 642.
  • a second low-pass filter 612 with cut-off frequency ⁇ ⁇ ⁇ filters the second baseband signal 642 into a second filtered signal 646.
  • a second ADC 616 then digitizes the second filtered signal 646 to generate a second digital waveform 650.
  • a phase shifter 624 phase-shifts the LO signal 638 by 90° prior to the first mixer 606.
  • the splitter 604, first mixer 606, second mixer 608, and phase shifter 624 cooperatively act as an IQ demodulator that is one example of the IQ demodulator 202 of the signal-processing circuit 200 of FIGS.2A, 3A, and 4A.
  • the low-pass filters 610 and 612 are examples of the low-pass filters 206 and 208, respectively, of the signal-processing Client Ref. CU5891B-PCT1 Attorney Docket No. P2049WO/00604329 circuit 200.
  • the baseband signals 640 and 642 are in-phase and quadrature signals similar to ⁇ ( ⁇ ) and ⁇ ( ⁇ ).
  • the radiometer 600 also includes a signal processor 620 that processes the digital waveforms 648 and 650 to determine their cross-correlation ⁇ ⁇ ( ⁇ ) therebetween for various values of the time lag ⁇ .
  • the signal processor 620 is one example of the correlator 210 shown in FIGS. 2A, 3A, and 3B. Based on the cross-correlation ⁇ ⁇ ( ⁇ ) , the signal processor 620 determines whether the input signal 136 contains interference within the frequency band. If no interference is found (i.e., the frequency band is clean), the signal processor 620 assumes that the input signal 136 contains only thermal noise. The signal processor 620 may then process one or both of the digital waveforms 648 and 650 to determine the radiometric temperature 130.
  • the radiometer 600 includes a controller 622 that outputs an LO control signal 654 that, when applied to the LO 618, tunes the LO frequency of the LO signal 638. Tuning the LO frequency changes the frequency band processed by the radiometer 600 (e.g., the frequency band 228 in FIGS. 2B, 3B, and 4B).
  • the signal processor 620 may send a signal 652 to the controller 622 to switch to a different frequency band. The signal processor 620 may then delete the digital waveforms 648 and 650.
  • FIG. 7 is a schematic diagram of a radiometer 700 that is similar to the radiometer 600 of FIG. 6 except that it includes a radiometric branch 728.
  • a bandpass filter 702 filters the first baseband signal 640 is into a bandpass-filtered signal 730 that is centered at an intermediate frequency ⁇ ⁇ .
  • a detector 704 detects the bandpass- filtered signal 730 to generate a temperature signal 732.
  • a low-pass filter 706 with a time constant ⁇ ⁇ filters the temperature signal 732 into a filtered temperature signal 734.
  • the bandpass-filtered signal 730 may be thought of as a time-sequence of random electrical pulses. Due to the bandpass filter 702, the bandpass-filtered signal 730 has no DC component and is therefore bipolar, i.e., approximately half of the electrical pulses are positive while the remaining half are negative.
  • the low-pass filter 706 time-integrates the positive pulses of the temperature signal 732 (e.g., using a capacitor). The voltage at the output of the low-pass Client Ref.
  • CU5891B-PCT1 Attorney Docket No. P2049WO/00604329 filter 706 (i.e., the filtered temperature signal 734) is therefore proportional to the number of positive pulses integrated by the low-pass filter 706 within the most-recent time interval of ⁇ ⁇ .
  • the bandpass-filtered signal 730 has a bandwidth ⁇ ⁇ ⁇ that may be hundreds of megahertz, or more.
  • the rectification and time-integration performed in the radiometric branch 728 down-converts the wide-band noise of the signal 730 into an equivalent time-integrated, low-bandwidth signal (i.e., the filtered temperature signal 734).
  • ⁇ ⁇ ⁇ may be much smaller than the bandwidth ⁇ ⁇ ⁇ of the waveforms 648 and 650.
  • a typical value of ⁇ ⁇ ⁇ is 1 kHz, as compared to 1 MHz for ⁇ ⁇ ⁇ . Therefore, the ADC 708 may have a sampling rate that is several orders of magnitude less than that of the ADCs 614 and 616. In general, low-speed ADCs consume less power than their higher-speed counterparts.
  • the bandwidth ⁇ ⁇ ⁇ of the bandpass-filtered signal 730 may be greater than ⁇ ⁇ ⁇ .
  • the radiometric branch 728 detects noise over a frequency range that spans several consecutive neighboring frequency bands, each with a width ⁇ ⁇ ⁇ .
  • these wideband radiometric measurements speed up acquisition of radiometric data. Specifically, the uncertainty of a radiometric measurement scales inversely with the square-root of the bandwidth. Thus, a measurement with a 100-MHz bandwidth has ten times lower uncertainty than a measurement with a 1-MHz bandwidth.
  • the procedure described above for FIG.5 may be used to identify large frequency windows that are clean. If a clean frequency window of width ⁇ ⁇ ⁇ cannot be found, then the bandwidth of the radiometric measurement should be reduced. This may be implemented by using, for the bandpass filter 702, a filter having an electronically controllable bandwidth. Alternatively, several bandpass filters of different fixed bandwidths may be used. In this case, one or more switches may be used to electrically connect only one of the bandpass filters into the radiometric branch 728. Changing the bandwidth may then be performed by controlling the one or more switches to change between bandpass filters.
  • the radiometer 700 also includes a correlator 712 that implements the correlator 210 of FIG.2A.
  • the correlator 712 outputs cross-correlation data 718 to a signal processor 720 that also receives the digital temperature waveform 710.
  • the signal processor 720 processes the digital temperature waveform 710 to determine the radiometric temperature 130. Otherwise, the signal processor 720 ignores or deletes the digital temperature waveform 710.
  • the signal processor 720 and correlator 712 may be implemented in the same circuit (e.g., a single integrated circuit or processor).
  • the correlator 712 may alternatively be implemented with analog circuitry, in which case the ADCs 614 and 616 are not needed.
  • the radiometric temperature 130 may be determined by processing one or both of the waveforms 648 and 650 instead of, or in addition to, using the radiometric branch 728.
  • the waveforms 648 and 650 may be individually squared and then added together to obtain a digital ⁇ ⁇ waveform. This processing may be performed by the signal processor 720 (in which case the waveforms 648 and 650 may be directly routed to the signal processor 720).
  • the radiometer 700 therefore differs from the radiometer 600 in that different signals are used for cross-correlation (i.e., interference detection) and radiometry.
  • the radiometer 700 has another radiometric branch, similar to the radiometric branch 728, that processes the first baseband signal 640 into a bandpass-filtered signal similar to the bandpass-filtered signal 730.
  • radiometric measurement data may be acquired at twice the rate, as compared to having only one radiometric branch.
  • FIG. 8 is a schematic diagram of a radiometer 800 that is similar to the radiometer 700 of FIG.7 except that it uses a switchable resistor at its input to calibrate noise temperature. With this switchable resistor, the radiometer 800 is a type of Dicke radiometer.
  • the switchable resistor may be used to implement lock-in detection that cancels systematic effects arising in the front-end amplifier 602, notably variations in the gain (e.g., as caused by temperature fluctuations and drifts in power-supply voltage).
  • the radiometer 800 includes a Dicke switch 810 prior to the input of the front- end amplifier 602. In a first position, the Dicke switch 810 connects the input of the amplifier 602 to the transmission line 106, thereby feeding the amplifier 602 with the input signal 136. In a second position, the Dicke switch 810 connects the input of the amplifier 602 to a reference resistor ⁇ ⁇ , thereby feeding the amplifier 602 with thermal noise.
  • the radiometer 800 also includes a temperature sensor 804 in thermal contact with the reference resistor ⁇ ⁇ .
  • the temperature sensor 804 is electrically connected to the signal processor 720, which uses the temperature sensor 804 to determine the temperature of the reference resistor ⁇ ⁇ and therefore the Johnson noise generated by the reference resistor ⁇ ⁇ .
  • Client Ref. CU5891B-PCT1 Attorney Docket No. P2049WO/00604329 [0058]
  • the radiometer 800 also includes a function generator 812 that outputs a modulation signal 814 that controls the Dicke switch 810 to switch back-and-forth between the first and second positions at a modulation frequency. This back-and-forth switching causes the digital temperature waveform 710 to be modulated at the same modulation frequency.
  • FIG. 9 is a schematic diagram of a radiometer 900 that is similar to the radiometer 800 of FIG.8 except that it implements frequency-domain reflectometry. With this functionality, the radiometer 800 may correct radiometric temperature measurements for the non-perfect transmission of thermal radiation from the tissue stack 104 into the microwave probe 124 (i.e., impedance mismatch). For clarity, the function generator 812 and temperature sensor 804 are not shown in FIG.9.
  • the radiometer 900 is capable of performing the same temperature-calibrating lock-in detection as the radiometer 800. Also for clarity, the radiometric branch 728 and ADCs 614 and 616 are not shown in FIG.9. [0060]
  • the radiometer 900 includes a directional coupler 902 between the Dicke switch 810 and the front-end amplifier 602. Alternatively, the directional coupler 902 may be located between the transmission line 106 and the Dicke switch 810.
  • the radiometer 900 also includes a switch 910. In a first position (as shown in FIG.9), the switch 910 connects a portion of LO signal 638 to the directional coupler 902 as a reflectometry source signal 932.
  • the directional coupler 902 couples the source signal 932 to the transmission line 106 (assuming the Dicke switch 810 is in the first position, as shown in FIG.9).
  • the source signal 932 propagates along the transmission line 106 in the direction opposite to the input signal 136.
  • a portion of the source signal 932 is reflected, creating a reflected signal 934 that propagates back along the transmission line 106, through the directional coupler 902, and into the front-end amplifier 602.
  • the coupler 902 may have a weak coupling coefficient (e.g., -30 dB or less) so that the resistor connected to it does not add significant thermal noise to the radiometric measurements.
  • the radiometer 900 includes a signal processor 916 that determines the amplitude of the reflected signal 934.
  • the signal processor 916 may receive the digital waveforms 648 and 650. Assuming that the amplitude of the reflectometry source signal 932 is known, the signal processor 916 determines the reflection coefficient by dividing the Client Ref. CU5891B-PCT1 Attorney Docket No. P2049WO/00604329 amplitude of the reflected signal 934 by the amplitude of the source signal 932. From this, the signal processor 916 determines the transmission coefficient between the tissue stack 104 and microwave probe 124 (e.g., by subtracting the reflection coefficient from 1).
  • the signal processor 916 then adjusts a radiometric temperature measurement with the transmission coefficient to obtain a more accurate estimate of the radiometric temperature. Note that the signal processor 916 determines both the amplitude and phase of the reflection coefficient, and therefore the transmission coefficient.
  • the switch 910 may be controlled (e.g., via a control signal 904 outputted by the controller 922) to transition to a second position in which the LO signal 638 is not connected to the directional coupler 902.
  • the radiometer 900 may then perform interference detection and radiometry as described above. As shown in FIG. 9, the switch 910 may be controlled by the controller 922 via a control signal 904.
  • the radiometer 900 determines the transmission coefficient at the LO frequency.
  • FIG. 10 is a schematic diagram of a radiometer 1000 that is similar to the radiometer 900 of FIG. 9 except that it implements white-noise reflectometry instead of frequency-domain reflectometry. For clarity, the radiometric branch 728 and ADCs 614 and 616 are not shown in FIG.10.
  • the switch 910 when in the first position (as shown in FIG.10), connects a white noise source 1002 to the directional coupler 902.
  • the radiometer 1000 also includes a reflection switch 1010 that, when in a first position (as shown in FIG.9), connects the white noise 1004 to the transmission line 106. After propagating down the transmission line 106, some of the white noise 1004 reflects off the microwave probe 124 as reflected noise 1006 that propagates back along the transmission line 106 and into the front-end amplifier 602. Thus, the white noise 1004 acts like the reflectometry source signal 932 of FIG.9. [0065] When the reflection switch 1010 is in the second position, the white noise 1004 is grounded, causing it to reflect at the switch 1010.
  • the switch 1010 in the second position, connects the white noise 1004 to an open circuit, which will also cause the white noise 1004 to reflect.
  • the reflection propagates through the directional Client Ref. CU5891B-PCT1 Attorney Docket No. P2049WO/00604329 coupler 902 and into the front-end amplifier 602.
  • the signal processor 916 determines the amplitude of the white noise 1004.
  • the signal processor 916 divides the amplitude of the reflected noise 1006 by the amplitude of the white noise 1004 to determine the magnitude of the reflection coefficient, and therefore the magnitude of the transmission coefficient. Note that white-noise reflectometry cannot determine the phase of the reflection coefficient.
  • the radiometer 1000 implements “reflectometry” lock-in detection by driving the reflection switch 1010 with a modulation signal 1014 that is generated by a function generator 1012. This modulation causes the digital waveforms 648, 650, and 710 to be modulated.
  • the signal processor 916 acts as a lock-in amplifier, using the modulation signal 1014 to demodulate any of these modulated waveforms.
  • the modulation signal 1014 may have a frequency between 1 and 100 kHz.
  • reflectometry lock-in detection may be used to correct for amplitude drift of the white noise 1004.
  • Reflectometry lock-in detection may also correct for changes in transmission (e.g., impedance mismatch) due to movement between the sensor head 120 and the skin tissue 110 (e.g., when the patient moves).
  • Reflectometry lock-in detection may also be implemented with the radiometer 900 of FIG.9 to determine the amplitude of the reflectometry source signal 932.
  • the radiometer 900 performs two lock-in detection schemes at the same time. Since the source signal 932 is coherent, the signal processor 916 determines both the amplitude and phase of the reflection coefficient.
  • the reflection switch 1010 may be located between the transmission line 106 and the Dicke switch 810.
  • the reflection switch 1010 may be located between the Dicke switch 810 and the front-end amplifier 602.
  • the reflection switch 1010 and Dicke switch 810 may be implemented as one single-pole three- throw (SP3T) switch.
  • the switches 1010 and 810 may be implemented using three inputs of a single-pole four-throw (SP4T) switch.
  • the radiometer 1000 of FIG. 10 may additionally implement the temperature- calibration lock-in detection shown in FIG. 9. In this embodiment, the radiometer 1000 performs two lock-in detection schemes at the same time.
  • the Dicke switch 810 may be located between the transmission line 106 and the reflection switch 1010.
  • the Dicke switch 810 may be located between the reflection switch 1010 and the directional coupler 902.
  • the reflection switch 1010 and Dicke switch 810 may be implemented as one single-pole three- throw (SP3T) switch. Alternatively, the switches 1010 and 810 may be implemented using three inputs of a single-pole four-throw (SP4T) switch.
  • SP3T single-pole three- throw
  • SP4T single-pole four-throw
  • Client Ref. CU5891B-PCT1 Attorney Docket No. P2049WO/00604329 Monitoring Interference Over Time [0070]
  • any of the radiometers described herein may additionally implement one or more of several strategies to monitor interference over time and adapt radiometric temperature measurements accordingly. For example, in some embodiments, the radiometer maintains an electronic record of the status of each frequency band it detects.
  • the electronic record may be implemented, for example, as a data table stored in memory (e.g., volatile random-access memory or non-volatile flash memory) that is in electronic communication with the radiometer (e.g., the signal processor 720) or a processor that, in turn, is in electronic communication with the radiometer.
  • Each band may be identified in the table by its center frequency and bandwidth, or by its upper and lower frequencies. Alternatively or additionally, each band may be identified by a key that uniquely identifies the band among all of the bands stored in the data table.
  • the data table may also store for each band a binary flag that indicates whether the band is clean or contaminated. Alternatively or additionally, the data table may store the most-recent value of the cross- correlation coefficient ⁇ measured for the band.
  • the radiometer When the radiometer performs interference detection for a band, it may update the entry for the band in the data table. For example, when a band that was previously found to be contaminated is more-recently found to be clean, the radiometer may change the corresponding binary flag in the data table to reflect this change in status. Similarly, when a band that was previously found to be clean is more-recently found to be contaminated, the radiometer may again change the corresponding binary flag accordingly. [0072] The radiometer may use the data table to identify wideband frequency spans that are clean. Such wideband spans are useful for the radiometric measurements performed with the radiometric branch 728, as described above with respect to FIG. 7. The radiometer may perform interference detection on any band when it is not also performing radiometry.
  • the radiometer functions as a coherent detector.
  • the radiometer may simultaneously perform interference detection for only the one band at the center of the frequency span being radiometrically measured. This ability to perform interference detection simultaneously with radiometry may be thought of as “real-time” interference detection.
  • the data table additionally stores, for each band, a time stamp indicating when interference detection was last performed on the band.
  • the radiometer may use the time stamps to determine which band to perform interference detection on next. For example, the radiometer may search the data Client Ref. CU5891B-PCT1 Attorney Docket No. P2049WO/00604329 table for the oldest time stamp and perform interference detection on the corresponding band.
  • the radiometer preferentially performs interference detection on frequency bands that it recently used for radiometry.
  • the radiometer may additionally use these cross-correlation coefficients to select the next band.
  • the radiometer includes a time-out functionality that automatically identifies a band as contaminated when a certain amount of time has elapsed since interference detection has been performed on the band.
  • the bands may have different time-out durations. For example, bands that are known to be particularly prone to contamination may be assigned a relatively short time-out duration. Similarly, bands that are known to be clean for extended periods of time may be assigned a relatively long time-out duration.
  • the radiometer may have two data tables: a first table of contaminated bands and a second table of clean bands.
  • the radiometer may also have a third table of bands whose interference status is unknown. When the status of a band changes, it is moved from one table to another.
  • a method for microwave radiometry includes receiving, by a microwave probe, thermal radiation emitted by a sample.
  • the method also includes amplifying an output of the microwave probe to generate an amplified signal, demodulating the amplified signal with a local-oscillator signal to obtain in-phase and quadrature signals, processing the in-phase and quadrature signals to generate a cross-correlation signal, detecting at least one of the in-phase and quadrature signals to generate a temperature signal, processing the temperature signal to at least partly determine a radiometric temperature of the sample, and outputting the radiometric temperature in response to the cross-correlation signal being less than a threshold.
  • the method further includes discarding the radiometric temperature in response to the cross-correlation signal being not less than the threshold.
  • Client Ref. CU5891B-PCT1 Attorney Docket No. P2049WO/00604329
  • said processing the temperature signal only occurs in response to the cross-correlation signal being less than the threshold.
  • the method further includes placing the microwave probe adjacent to the sample such that the sample is at least partially located within a near-field region of the microwave probe.
  • the method further includes changing a local-oscillator frequency of the local-oscillator signal.
  • the method further includes adjusting the radiometric temperature based on a transmission coefficient that quantifies transmission of the thermal radiation from the sample into the microwave probe.
  • the method further includes coupling a reflectometry source signal to the microwave probe, processing a reflection of the reflectometry source signal to determine a reflection coefficient, and determining the transmission coefficient based on the reflection coefficient.
  • said coupling includes coupling the local- oscillator signal to the microwave probe.
  • said coupling includes coupling electronic noise to the microwave probe.
  • said processing the in-phase and quadrature signals includes low-pass filtering the in-phase signal into a filtered in-phase signal, digitizing the filtered in-phase signal into a digital in-phase waveform, low-pass filtering the quadrature signal into a filtered quadrature signal, digitizing the filtered quadrature signal into a digital quadrature waveform, and processing the digital in-phase waveform and the digital quadrature waveform to generate the cross-correlation signal.
  • the method further includes low-pass filtering the temperature signal into a filtered temperature signal and digitizing the filtered temperature signal into a digital temperature waveform.
  • a bandwidth of the filtered temperature signal is less than that of the filtered in-phase signal and the filtered quadrature signal.
  • Said processing the temperature signal includes processing the digital temperature waveform to at least partly determine the radiometric temperature.
  • a microwave radiometer includes a front-end amplifier, a local oscillator, a demodulator, a correlator, a detector, and a signal processor.
  • the demodulator has a signal- input port connected to an output of the front-end amplifier, a local-oscillator port connected to Client Ref.
  • CU5891B-PCT1 Attorney Docket No. P2049WO/00604329 an output of the local oscillator, an in-phase output port, and a quadrature output port.
  • the correlator is configured to process in-phase and quadrature signals from the in-phase and quadrature output ports to generate a cross-correlation signal.
  • the detector is configured to detect one or both of the in-phase and quadrature signals to generate a temperature signal.
  • the signal processor is configured to process the temperature signal to at least partly determine a radiometric temperature.
  • the signal processor is also configured to output the radiometric temperature in response to the cross-correlation signal being less than a threshold.
  • the signal processor is further configured to discard the radiometric temperature in response to the cross-correlation signal being not less than the threshold.
  • the signal processor is further configured to process the temperature signal only in response to the cross- correlation signal being less than the threshold.
  • the microwave radiometer further includes a controller configured to control a frequency of a local-oscillator signal generated by the local oscillator.
  • the signal processor is further configured to adjust the radiometric temperature based on a transmission coefficient that quantifies transmission of thermal radiation from a sample into a microwave probe.
  • the microwave radiometer further includes a directional coupler, a switch, and a controller.
  • the directional coupler includes a coupler input port configured to electrically connect to the microwave probe, a coupler output port electrically connected to an input of the front-end amplifier, and a coupled port.
  • the switch is configured to electrically connect the output of the local oscillator to the coupled port of the directional coupler.
  • the controller is configured to control the switch to couple a reflectometry source signal from the output of the local oscillator to the microwave probe.
  • the signal processor is further configured to process a reflection of the reflectometry source signal to determine a reflection coefficient of the microwave probe.
  • the signal processor is further configured to determine the transmission coefficient based on the reflection coefficient.
  • the microwave radiometer further includes a directional coupler, an electronic noise source, a switch, and a controller.
  • the directional coupler includes a coupler input port configured to electrically connect to the Client Ref. CU5891B-PCT1 Attorney Docket No.
  • P2049WO/00604329 microwave probe a coupler output port electrically connected to an input of the front-end amplifier, and a coupled port.
  • the switch is configured to electrically connect an output of the electronic noise source to the coupled port of the directional coupler.
  • the controller is configured to control the switch to couple a reflectometry source signal from the output of the electronic noise source to the microwave probe.
  • the signal processor is further configured to process a reflection of the reflectometry source signal to determine a reflection coefficient of the microwave probe.
  • the signal processor is further configured to determine the transmission coefficient based on the reflection coefficient.
  • the microwave radiometer further includes a first low-pass filter configured to low-pass filter the in-phase signal into a filtered in-phase signal, a first digitizer configured to digitize the filtered in-phase signal into a digital in-phase waveform, a second low-pass filter configured to low-pass filter the quadrature signal into a filtered quadrature signal, and a second digitizer configured to digitize the filtered quadrature signal into a digital quadrature waveform.
  • the correlator is configured to process the digital in-phase waveform and the digital quadrature waveform.
  • the microwave radiometer further includes a third low-pass filter configured to low-pass filter the temperature signal into a filtered temperature signal.
  • the microwave radiometer further includes a third digitizer configured to digitize the filtered temperature signal into a digital temperature waveform.
  • the third low-pass filter has a third cutoff frequency that is less than a first cutoff frequency of the first low-pass filter and a second cutoff frequency of the second low-pass filter.
  • the signal processor is configured to process the digital temperature waveform to at least partly determine the radiometric temperature.
  • the microwave radiometer further includes a microwave probe configured to electrically connect to an input of the front-end amplifier.
  • a method for microwave radiometry includes tuning a local oscillator to generate a local-oscillator signal having a local-oscillator frequency near a center frequency of a frequency band having a bandwidth. The method also includes amplifying an output of a microwave probe to generate an amplified signal and demodulating the amplified signal with the local-oscillator signal to obtain in-phase and quadrature signals. The method also includes processing the in-phase and quadrature signals to generate a cross-correlation signal. The Client Ref.
  • CU5891B-PCT1 Attorney Docket No. P2049WO/00604329 method also includes one or both of (i) saving the center frequency and the bandwidth of the frequency band in a table of contaminated bands in response to the cross-correlation signal being greater than a threshold and (ii) saving the center frequency and the bandwidth of the frequency band in a table of clean bands in response to the cross-correlation signal being not greater than the threshold. [0100] (C2) In the method denoted (C1), the method further includes outputting one or both of the table of contaminated bands and the table of clean bands.
  • the method further includes receiving, with the microwave probe, thermal radiation emitted by a sample and tuning the local oscillator to the center frequency of an interference-free band that is not stored in the table of contaminated bands.
  • the method further includes detecting, after said tuning the local oscillator, one or both of the in-phase and quadrature signals to generate a temperature signal.
  • the method further includes processing the temperature signal to at least partly determine a radiometric temperature of the sample and outputting the radiometric temperature.
  • the method further includes receiving, with the microwave probe, thermal radiation emitted by a sample and tuning the local oscillator to the center frequency of an interference-free band that is stored in the table of clean bands.
  • the method further includes detecting, after said tuning the local oscillator, one or both of the in-phase and quadrature signals to generate a temperature signal.
  • the method further includes processing the temperature signal to at least partly determine a radiometric temperature of the sample and outputting the radiometric temperature.
  • the method further includes low-pass filtering the in-phase signal to obtain a first filtered signal and low-pass filtering the quadrature signal to obtain a second filtered signal.
  • Said processing includes processing the first filtered signal and the second filtered signal to generate the cross-correlation signal.
  • said low-pass filtering the in-phase signal includes low-pass filtering the in-phase signal with a first low-pass filter having a first cutoff frequency that is no greater than one-half of the bandwidth.
  • Said low-pass filtering the quadrature signal comprises low-pass filtering the quadrature signal with a second low-pass filter having a second cutoff frequency that is no greater than one-half of the bandwidth.
  • the method further includes placing the microwave probe adjacent to the sample such that the sample is at least partially located within a near-field region of the microwave probe.
  • a microwave radiometer includes a front-end amplifier and a local oscillator tunable to generate a local-oscillator signal having a local-oscillator frequency near a center frequency of a frequency band having a bandwidth.
  • the microwave radiometer also includes a demodulator having a signal-input port connected to an output of the front-end amplifier, a local-oscillator port connected to an output of the local oscillator, an in-phase output port, and a quadrature output port.
  • the microwave radiometer also includes a correlator configured to process in-phase and quadrature signals from the in-phase and quadrature output ports to generate a cross-correlation signal.
  • the microwave radiometer also includes a processor and a memory in electronic communication with the processor.
  • the memory stores one or both of a table of contaminated bands and a table of clean bands.
  • the memory also stores machine- readable instructions that, when executed by the processor, control the microwave radiometer to one or both of (i) save the center frequency and the bandwidth of the frequency band in the table of contaminated bands in response to the cross-correlation signal being greater than a threshold and (ii) save the center frequency and the bandwidth of the frequency band in the table of clean bands in response to the cross-correlation signal being less than the threshold.
  • the memory stores additional machine-readable instructions that, when executed by the processor, control the microwave radiometer to output one or both of the table of contaminated bands and the table of clean bands.
  • the microwave radiometer further includes controller configured to control the local oscillator to the center frequency of an interference-free band that is not stored in the table of contaminated bands, a detector configured to detect one or both of the in-phase and quadrature signals to generate a temperature signal, and a signal processor configured to process the temperature signal to at least partly determine a radiometric temperature.
  • the microwave radiometer further includes a controller configured to tune the local oscillator to the center frequency of an interference-free band that is stored in the table of clean bands, a detector configured to detect one or both of the in-phase and quadrature signals to generate a temperature signal, and a signal processor configured to process the temperature signal to at least partly determine a radiometric temperature.
  • the microwave radiometer further includes a microwave probe configured to electrically connect to an input of the front-end amplifier.
  • the microwave radiometer further includes a first low-pass filter configured to filter the in-phase signal into a first filtered signal and a second low-pass filter configured to filter the quadrature signal into a second filtered signal.
  • the correlator is configured to process the first filtered signal and the second filtered signal to generate the cross-correlation signal.
  • the first low-pass filter has a first cutoff frequency that is no greater than one-half of the bandwidth.
  • the second low-pass filter has a second cutoff frequency that is no greater than one-half of the bandwidth.

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Abstract

La présente invention porte sur un procédé de radiométrie par micro-ondes qui comprend la réception, par une sonde à micro-ondes, d'un rayonnement thermique émis par un échantillon. Le procédé comprend également l'amplification d'une sortie de la sonde hyperfréquence pour générer un signal amplifié, la démodulation du signal amplifié avec un signal d'oscillateur local pour obtenir des signaux en phase et en quadrature, le traitement des signaux en phase et en quadrature pour générer un signal de corrélation croisée, la détection d'au moins l'un des signaux en phase et en quadrature pour générer un signal de température, le traitement du signal de température pour déterminer au moins partiellement une température radiométrique de l'échantillon et l'émission de la température radiométrique si le signal de corrélation croisée est inférieur à un seuil.
PCT/US2024/020600 2023-03-20 2024-03-19 Radiomètre à micro-ondes avec détection d'interférence et procédés associés Pending WO2024196962A1 (fr)

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Citations (4)

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Publication number Priority date Publication date Assignee Title
US5708442A (en) * 1996-04-24 1998-01-13 Hughes Electronics Correlation radiometer imaging system
US20100061421A1 (en) * 2007-04-12 2010-03-11 Van De Velde Jean-Claude Radiometric thermometer
US20170340208A1 (en) * 2016-05-27 2017-11-30 The Regents Of The University Of Colorado Microwave thermometer for internal body temperature retrieval
WO2021001408A1 (fr) * 2019-07-03 2021-01-07 Airbus Defence And Space Sas Procédé et dispositif de calcul de fonctions de visibilité pour un radiomètre à synthèse d'ouverture interférométrique

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US5708442A (en) * 1996-04-24 1998-01-13 Hughes Electronics Correlation radiometer imaging system
US20100061421A1 (en) * 2007-04-12 2010-03-11 Van De Velde Jean-Claude Radiometric thermometer
US20170340208A1 (en) * 2016-05-27 2017-11-30 The Regents Of The University Of Colorado Microwave thermometer for internal body temperature retrieval
WO2021001408A1 (fr) * 2019-07-03 2021-01-07 Airbus Defence And Space Sas Procédé et dispositif de calcul de fonctions de visibilité pour un radiomètre à synthèse d'ouverture interférométrique

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STÄHLI O., MURK A., KÄMPFER N., MÄTZLER C., ERIKSSON P.: "Microwave radiometer to retrieve temperature profiles from the surface to the stratopause", ATMOSPHERIC MEASUREMENT TECHNIQUES, vol. 6, no. 9, pages 2477 - 2494, XP093226765, ISSN: 1867-8548, DOI: 10.5194/amt-6-2477-2013 *
SUN GUANGMIN, MA PAN, LIU JIE, SHI CHONG, MA JINGYAN, PENG LI: "Design and Implementation of a Novel Interferometric Microwave Radiometer for Human Body Temperature Measurement", SENSORS, MDPI, CH, vol. 21, no. 5, CH , pages 1619, XP093226758, ISSN: 1424-8220, DOI: 10.3390/s21051619 *

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