Subsurface Temperature Measurement via Multi-Frequency Radiometry
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Solution Overview
Problem
Radiometers operating at a single frequency face ambiguity in temperature measurements due to variations in electro-magnetic propagation caused by substrate resistivity, reluctance, and extraneous objects, limiting their effectiveness in subsurface temperature measurement applications.
Innovation Solution
A subsurface temperature measurement system that combines signals from a radiometer at differing frequencies, using a coupled antenna and signal processor to determine brightness temperature by compensating for these variations, and is configured in various devices such as boots, shoes, and robots for diverse applications including fire detection, planetary exploration, and structural analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a radiometer operates at a single frequency, then the device complexity is reduced, but measurement precision deteriorates due to ambiguity caused by variations in electro-magnetic propagation
Solution Approach 1:
The radiometer is divided into multiple independent frequency channels (e.g., 700 MHz and 1400 MHz), each operating at a specific frequency. This segmentation allows the system to measure temperature at different frequencies simultaneously, resolving the ambiguity problem while maintaining manageable device complexity through modular frequency channel design.
Solution Approach 2:
The system transitions from single-frequency measurement to multi-frequency measurement by adding the frequency dimension. By measuring temperature at multiple frequencies (700 MHz and 1400 MHz), the system gains additional information about electro-magnetic propagation characteristics, enabling accurate temperature determination despite variations in substrate properties.
2Measurement precision
If multiple frequencies are combined to compensate for propagation variations, then measurement precision improves, but device complexity increases
Solution Approach 1:
The system merges signals from multiple frequency channels (700 MHz and 1400 MHz) through a common signal processing architecture. The radiometer combines these signals and feeds them to a single processor that performs temperature calculation, reducing overall system complexity compared to having separate processing paths for each frequency.
Solution Approach 2:
The signal processing system automatically compensates for electro-magnetic propagation variations by using the multi-frequency signals themselves as the basis for correction. The processor uses the ratio or difference between frequencies to calculate temperature, eliminating the need for external calibration or complex manual adjustment procedures.
3Reliability
If the antenna is placed in contact with the substrate surface, then measurement capability improves for subsurface detection, but the ease of operation decreases due to requirement for direct contact
Solution Approach 1:
The antenna system is designed to function effectively both when in direct contact with the substrate and when positioned close to the surface. This multi-functionality allows the same antenna configuration to serve different operational modes (contact-based for high accuracy, proximity-based for ease of operation), resolving the contradiction between detection reliability and operational simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system reduces ambiguity in temperature measurements, enhancing the utility of subsurface temperature detection by providing accurate readings of subsurface features, such as underground fires, ice presence, and thermal activity, across different terrains and environments.
Implementation Method 1
Radiometers are used to measure electro-magnetic radiation emitted from remote objects. Radiometers that measure electro-magnetic radiation in the microwave and millimeter frequency range are commonly referred to as microwave and millimeter wave (MMW) radiometers, respectively.
Implementation Method 2
combine signals from the radiometer at differing frequencies to compensate for variations in electro-magnetic propagation due to various factors, potentially including resistivity of the substrate, reluctance of the substrate, and/or extraneous objects embedded in the substrate
Data Source
AI summary
According to certain embodiments, a temperature measurement system includes a radiometer coupled to an antenna and a signal processor. The radiometer is operable to generate two or more signals representing electro-magnetic radiation received at a corresponding two or more differing frequencies. The signal processor receives the two or more signals from the radiometer while the antenna is placed adjacent to a surface of a substrate, and compares the two or more signals with one another to determine a brightness temperature of the substrate at a depth of the substrate from the antenna.