Living Body Position Sensor Using Multi-Station Signal Integration
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Solution Overview
Problem
Existing techniques for estimating the position of a living body using radio signals have limitations, particularly when the body is stationary, as the detection area is narrow due to the insignificance of the Doppler effect, making it difficult to detect weak signals amidst internal noise and interference.
Innovation Solution
A sensor system comprising multiple transmitting and receiving stations that extract living-body components from radio signals, calculate position spectral functions using algorithms like MUSIC, and integrate these functions to estimate the position of a living body over a wider area without requiring the body to carry a special transmitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Doppler shift analysis is used to detect living bodies, then moving bodies can be detected, but stationary bodies cannot be detected because the Doppler effect is insignificant
Solution Approach 1:
The system divides the detection task into multiple receiving stations, each analyzing signals from different spatial perspectives. By segmenting the reception function across multiple stations and integrating their respective position spectral functions, the system achieves wide-area detection capability that overcomes the limitation of single-station narrow detection areas.
Solution Approach 2:
The system merges the detection results from multiple receiving stations by integrating their position spectral functions. This combination allows the system to detect stationary bodies across a wide area by consolidating the observational data from multiple spatial viewpoints, effectively overcoming the narrow detection area limitation.
2Adaptability or versatility
If multiple receiving stations are deployed to widen detection area, then detection coverage increases, but system complexity increases
Solution Approach 1:
Each receiving station is designed with multi-functionality, performing signal reception, living-body component extraction, and position spectral function calculation simultaneously. This universal design allows the system to expand detection coverage by simply adding identical multi-functional stations rather than designing complex specialized components for each station.
Solution Approach 2:
The system transitions from single-station detection to multi-station detection by adding a spatial dimension to the reception network. By distributing receiving stations across different locations and integrating their position spectral functions in the spatial domain, the system achieves wide-area detection while maintaining standardized station designs.
3Measurement precision
If signal processing is performed to extract living-body components, then detection accuracy improves, but processing complexity increases
Solution Approach 1:
The system extracts only the relevant living-body components from the received signals by identifying and isolating signal characteristics specific to living bodies (such as respiratory and cardiac movements). This extraction process removes unnecessary signal elements and focuses processing on discriminative features, improving detection accuracy while managing processing complexity through selective analysis.
Solution Approach 2:
The system replaces complex mechanical or hardware-based detection mechanisms with signal processing algorithms that analyze electromagnetic wave characteristics. By using digital signal processing to extract living-body components and calculate position spectral functions, the system achieves high measurement precision through software-based analysis rather than complex hardware configurations.
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 effectively estimates the position of a living body over a broader area with higher accuracy, even in cases where signals are weak, by integrating position spectral functions from multiple receiving stations, thus overcoming the limitations of previous methods.
Implementation Method 1
signal components transmitted from the transmission antenna and reflected by at least one living body
Implementation Method 2
PTL 1 discloses a technique with which the position and state of a person, which is a detection target, can be known by using a Fourier transform and analyzing a component that includes a Doppler shift
Data Source
AI summary
A sensor includes at least one transmitting station including a transmission antenna; a plurality of receiving stations each including a reception array antenna; a first circuit that extracts, from signals observed by the reception array antenna of each of the plurality of receiving stations, living-body components, which are signal components transmitted from the transmission antenna and reflected by at least one living body; a second circuit that calculates, from the extracted living-body components, a plurality of position spectral functions, which are evaluation functions for evaluating a position of the at least one living body when viewed from the plurality of respective receiving stations; and a third circuit that integrates the plurality of calculated position spectral functions into one position spectral function, and calculates at least one maximum value of the position spectral function obtained as a result of integration to estimate the position of the at least one living body.