Radar Direction Estimation via Complex Transfer Function Fluctuation Removal
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Solution Overview
Problem
Existing methods for estimating the direction or position of a living body using radio signals face challenges in accurately distinguishing between clock frequency errors and Doppler shifts, leading to difficulties in precise location determination.
Innovation Solution
The method involves calculating first complex transfer functions from reception signals, then performing arithmetic operations to reduce components related to clock fluctuations and timing variations, allowing for the extraction of moving body information and accurate direction or position estimation using a system with multiple antenna elements and signal processing techniques like MUSIC or Capon methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex transfer functions are calculated from reception signals to estimate direction or position, then measurement capability is improved, but clock fluctuation and timing fluctuation components interfere with accurate measurement
Solution Approach 1:
The patent extracts and removes the harmful clock fluctuation and timing fluctuation components from the complex transfer functions through arithmetic operations. By separating these fluctuation components from the Doppler shift components, the method isolates the useful moving body information while eliminating interference, thereby improving both measurement precision and reliability
Solution Approach 2:
The patent changes the parameter representation by performing arithmetic operations on complex transfer functions to transform them into a form where clock and timing fluctuations are separated from Doppler shifts. This parameter transformation enables selective extraction of moving body information at specific frequencies while suppressing fluctuation components
2Device complexity
If clock fluctuation components are present in complex transfer functions, then signal processing complexity is reduced, but direction estimation accuracy deteriorates
Solution Approach 1:
The patent performs preliminary arithmetic operations on the complex transfer functions before direction estimation to remove clock and timing fluctuation components. By preprocessing the transfer functions to eliminate harmful fluctuations, the method simplifies subsequent signal processing while improving estimation accuracy, as the fluctuation removal is done in advance
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
This approach enables the accurate estimation of a moving body's direction or position by removing phase rotations caused by frequency errors, effectively distinguishing between transmitter-receiver fluctuations and living body-derived Doppler shifts, even when clock synchronization is not maintained.
Implementation Method 1
transmitting a transmission signal to a measurement target area using the transmission antenna element; measuring reception signals which are received by each of the N reception antenna elements and include a reflected signal
Implementation Method 2
a reflected signal which is the transmission signal transmitted from the transmission antenna element that has been reflected by the moving body; extracting moving body information corresponding to a component related to the moving body
Data Source
AI summary
An estimating method includes: measuring and receiving reception signals including a reflected signal reflected by a moving body, for a first period equivalent to a cycle of movement of the moving body; calculating first complex transfer functions indicating propagation characteristics, from the reception signals measured in the first period; calculating second complex transfer functions having reduced components corresponding to fluctuations, from the first complex transfer functions; extracting moving body information corresponding to a component related to the moving body by extracting moving body information corresponding to a predetermined frequency range of the second complex transfer functions calculated; and estimating a direction in which the moving body is present using the moving body information.