Phaseless FMCW Multistatic Radar Imaging Without Time Synchronization
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Solution Overview
Problem
Classical multistatic Radar systems require direct Line of Sight (LoS) signals and time synchronization among distributed receivers, increasing system cost and complexity, while passive systems need spatially synchronized receivers for phase retrieval, limiting their applicability.
Innovation Solution
The method employs frequency-modulated continuous-wave (FMCW) multistatic Radar imaging that eliminates the need for direct LoS signals and time synchronization by using chirp signals with unknown random phase offsets, performing auto-correlation to generate phaseless measurement data, and solving a constrained optimization problem to estimate reflectivities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct LoS signal and time synchronization are used in multistatic Radar systems, then imaging accuracy is improved, but system complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the requirement for direct LoS signal and time synchronization from the multistatic Radar system. By using phaseless measurement techniques, the system removes these complex requirements while maintaining imaging capability through magnitude-only signal processing and optimization-based reconstruction methods
Solution Approach 2:
The patent changes the measurement parameter from phase-containing complex signals to phaseless magnitude-only measurements. This parameter transformation allows the system to operate without time synchronization and direct LoS signals, as the optimization algorithm can reconstruct images from magnitude measurements alone, fundamentally altering how the system extracts information from received signals
2Measurement precision
If direct LoS signal and time synchronization are implemented, then Radar imaging performance is improved, but system cost increases
Solution Approach 1:
The patent removes the expensive requirements for direct LoS signal paths and precise time synchronization hardware from the system architecture. By formulating the imaging problem in terms of phaseless measurements, the system achieves comparable imaging performance without these costly components, making multistatic Radar more economically viable
Solution Approach 2:
The patent employs computationally intensive but hardware-simple processing methods. Instead of investing in expensive synchronized hardware infrastructure, the system uses optimization algorithms and iterative reconstruction techniques that run on standard computing platforms, effectively replacing hardware complexity with software processing
3Measurement precision
If phase retrieval techniques are used in passive multistatic Radar, then imaging capability is improved, but time synchronization requirement increases system complexity
Solution Approach 1:
The patent inverts the traditional approach by not trying to retrieve phase information from magnitude measurements (which would require synchronization), but instead formulating the problem to directly solve for target reflectivities using magnitude-only measurements. This inversion of the measurement paradigm eliminates the synchronization requirement while maintaining imaging capability
Solution Approach 2:
The patent fundamentally changes the measurement parameter from complex phase-containing signals to phaseless magnitude measurements. This parameter change allows passive multistatic Radar to operate without time synchronization, as the optimization-based reconstruction can work exclusively with magnitude information, removing the synchronization complexity entirely
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 reduces system complexity and cost by eliminating the need for direct LoS signals and time synchronization, providing effective Radar imaging with asynchronous receivers.
Implementation Method 1
transmitting via a frequency-modulated continuous-wave (FMCW) non-cooperative transmitter a plurality of chirp signals
Implementation Method 2
receiving via a plurality of FMCW multistatic distributed Radio Detection And Ranging (Radar) receivers, a plurality of FMCW Radar imaging signals back scattered from the scene of interest
Implementation Method 3
mixing, the plurality of FMCW Radar imaging signals at each of the plurality of FMCW multistatic distributed Radar receivers with the corresponding generated reference chirp signal
Data Source
AI summary
Existing multistatic configurations of Radar systems requires a direct LoS signal and/or time synchronization among the Radar transmitter and the multistatic distributed Radar receivers. The present disclosure provides a phaseless frequency-modulated continuous-wave multistatic Radar (PFMR) imaging that relaxes requirement of the direct LoS signal and only requires a plurality of parameters of a FMCW signal comprising a chirp signal rate, a carrier frequency and, a period of chirp to be known. Further, it also removes condition of the time synchronization among a plurality of FMCW multistatic distributed Radar receivers. However, because of absence of the time synchronization among a plurality of FMCW multistatic distributed Radar receivers, an unknown random phase offset appears after deramping. The present disclosure eliminates the unknown random phase offset, by performing autocorrelation function on a mixed signal, resulting in a phaseless measurement data corresponding to a plurality of FMCW Radar imaging signals.