Progressive Phase Rotation for IQ-Imbalance-Robust Radar Detection
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Solution Overview
Problem
Digitally modulated radars suffer from IQ imbalance and front-end non-idealities such as power amplifier non-linearity, leading to artifacts like range sidelobes and ghosts in radar range-Doppler maps, which degrade performance.
Innovation Solution
A method and radar system that generates radar signals with a progressive phase rotation in the digital domain, using code sequences with specific parameters Lc, M, and K to mitigate IQ imbalance and power amplifier non-linearity, allowing for robust signal generation and processing across various modulation schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional radar signal generation is used, then the radar can operate with standard modulation schemes, but IQ imbalance and power amplifier non-linearity generate artifacts like range sidelobes and ghosts that degrade performance
Solution Approach 1:
The patent applies preliminary action by pre-compensating for IQ imbalance in the transmitted signal through digital signal processing before transmission. The system calculates compensation parameters based on estimated IQ imbalance characteristics and applies them to the baseband signal, thereby preventing the generation of range sidelobes and ghosts at the source rather than attempting to correct them after reception
Solution Approach 2:
The patent changes the parameter of phase rotation in the transmitted signal by applying a progressive phase rotation across different time samples or pulses. This phase modulation approach transforms the signal characteristics to be more robust against IQ imbalance, effectively changing the signal's phase parameter to mitigate the harmful effects of transmitter non-idealities
2Reliability
If robust signal processing is applied to cancel non-idealities, then artifacts are reduced, but the processing complexity increases
Solution Approach 1:
The patent reduces processing complexity by performing compensation in advance during signal transmission rather than requiring complex post-processing. The preliminary compensation parameters are calculated once and applied to the transmitted signal, eliminating the need for sophisticated artifact suppression algorithms in the reception and processing stage
Solution Approach 2:
The patent uses a simplified modeling approach where the complex non-idealities are represented by equivalent compensation parameters that can be applied through straightforward digital signal processing operations. Instead of modeling and correcting each individual artifact source, the system creates a simplified compensatory signal that replicates the desired correction effect
Data Source
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Figure 3A~3B
AI summary
A method is provided for facilitating radar detection robust to IQ imbalance. The method comprises the step of generating (104) a radar signal in digital domain comprising a number of M periodic repetitions of a code sequence with a length Lc, multiplied with a progressive phase rotation ej.πK.n, where Lc and M are integers, K is an integer or a non-integer, and n is a discrete integer variable. The method further comprises the step of generating (105) a process input signal in digital domain from a reflection signal corresponding to the radar signal by multiplying the reflection signal with a progressive phase rotation e−j.πK.n. In this context, K is defined such that a ratio LcK is a non-integer, and M is defined such that a ratio Lc.MK is an integer.