3D Radar Imaging with Simultaneous Phase-Coded MIMO Transmission
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Solution Overview
Problem
The existing radar devices using a time division multiplex-multiple input multiple output (TDM-MIMO) system face issues with blurring in three-dimensional imaging due to the inability to coherently add reception signals from different transmission antennas when the subject is moving, resulting in low resolution images.
Innovation Solution
A radar device that employs a transmission and reception system with linearly arranged antennas, where transmission signals are simultaneously sent from multiple antennas with varying initial phase changes, and reception signals are processed to generate three-dimensional radar images through coherent addition of signals from different antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a time division multiplex-MIMO system is used to widen virtual aperture with multiple transmission antennas, then the imaging coverage and detection capability are improved, but when the subject moves during transmission antenna switching, the reception signals cannot be coherently added resulting in blurred images and reduced resolution
Solution Approach 1:
The system transitions from static time-division multiplexing to dynamic simultaneous transmission with differential phase coding. Multiple transmission antennas transmit signals at the same time rather than sequentially, and the phase of each antenna is dynamically adjusted according to its position to maintain coherence despite subject movement, thereby preserving both large virtual aperture and high image resolution
Solution Approach 2:
The invention changes the transmission parameter configuration from uniform time-division switching to differential phase assignment. Each transmission antenna is assigned a specific initial phase value that varies according to its spatial position, allowing the system to maintain coherent signal addition across multiple antennas while simultaneously transmitting, thus resolving the resolution degradation issue
2Device complexity
If transmission antennas are switched in time division manner, then device complexity is reduced compared to simultaneous multi-antenna transmission, but productivity and imaging efficiency decrease due to longer acquisition time
Solution Approach 1:
The system implements continuous simultaneous transmission from all antennas rather than intermittent time-division switching. This continuous parallel operation maintains useful action throughout the measurement period, significantly improving imaging efficiency and productivity while the differential phase coding keeps signal processing manageable through structured phase relationships
3Measurement precision
If the pulse repetition interval is reduced to minimize subject movement influence, then measurement precision is improved, but the time available for signal processing and coherent addition is reduced
Solution Approach 1:
The system applies preliminary phase coding to each transmission antenna signal before transmission, embedding position-dependent phase information in advance. This preliminary action allows the receiver to perform coherent addition more efficiently with shorter integration times, as the phase relationships are pre-established rather than requiring longer processing to resolve
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 enhances the resolution of three-dimensional radar images by reducing the influence of subject movement during signal transmission intervals, allowing for coherent addition of reception signals and improving image clarity.
Implementation Method 1
receiving reflected waves of the radio wave reflected by the subject
Implementation Method 2
generates two dimensional frequency signals by performing one dimensional Fourier transform on a plurality of reception signals
Implementation Method 3
multiplexes the transmission signals on a Doppler frequency axis
Data Source
AI summary
A radar device includes: a control unit to cause a series of processing to be repeatedly executed, the series of processing including transmitting transmission signals to space using transmission antennas arranged linearly, receiving reflected signals that are the transmission signals reflected in the space using reception antennas linearly arranged in the same direction as the transmission antennas, transmitting the transmission signals simultaneously from the transmission antennas, receiving the reflected signals by the reception antennas, and acquiring digital data; and a signal processing unit to generate a three-dimensional radar image of a target moved in a direction crossing an antenna arrangement direction of the transmission antennas and the reception antennas by using the digital data sequentially acquired in the series of processing repeatedly executed as two-dimensional array data.