Radar Signal Processing for Doppler Sidelobe Reduction
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Solution Overview
Problem
Conventional radar systems face issues with increased sidelobes due to cross correlation between reception signals from different bands when Doppler frequency is present, leading to incorrect range measurement and degraded detection performance.
Innovation Solution
A radar system with multiple transmission radars emitting signals with different frequencies, using a frequency domain transforming unit to align Doppler frequencies into the same velocity bin, a correlation unit for pulse compression, and an integrating unit for band-synthesis, along with a target candidate detecting unit to improve detection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reception signals from different bands are integrated coherently to improve range resolution, then range resolution is improved, but sidelobes increase due to cross correlation when Doppler frequency is present
Solution Approach 1:
The patent segments the reception signal processing by separating signals from different transmission frequency bands before integration. By processing each band's reception signal independently through pulse compression and then integrating the results, the system maintains coherent integration benefits while reducing cross-correlation sidelobes that would occur with direct integration of mixed-band signals.
Solution Approach 2:
The patent introduces an intermediary processing stage between signal reception and final integration. The reception signals undergo separate pulse compression processing for each transmission frequency band, acting as an intermediary step that prepares the signals for coherent integration while minimizing harmful cross-correlation effects.
2Device complexity
If reception signals are integrated at fixed range locations assuming no Doppler frequency, then integration is simplified, but range measurement becomes incorrect when Doppler frequency is present
Solution Approach 1:
The patent applies dynamic adjustment to the integration process by compensating for Doppler frequency effects. Instead of using fixed range locations for integration, the system dynamically adjusts the integration locations based on the detected Doppler frequency, ensuring accurate range measurement while maintaining integration simplicity through systematic compensation.
3Adaptability or versatility
If transmission frequencies differ for each transmission radar to enable frequency diversity, then detection coverage is improved, but coherent integration becomes impossible due to phase differences
Solution Approach 1:
The patent changes the approach by processing signals in the frequency domain separately for each transmission frequency band. By performing pulse compression and integration operations on each frequency band's signals independently before combining results, the system maintains the frequency diversity benefits of different transmission frequencies while achieving reliable detection through systematic frequency-domain processing.
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 enhances target detection performance by coherently integrating signals across different transmission frequencies, reducing sidelobe interference and improving range measurement accuracy even under Doppler frequency influence.
Implementation Method 1
a receiving unit configured to convert received signals of the transmission signals that return from a target on reflection, into a reception video signal
Implementation Method 2
a frequency domain transforming unit configured to transform the reception video signal into signals based on a velocity and a range in such a way that Doppler frequencies of the target belongs to a same velocity bin number regardless of a change in the frequencies of the transmission signals
Data Source
AI summary
A frequency domain transforming unit (231-1) performs a transform into a frequency domain in such a way that a Doppler velocity bin is the same for each of different transmission frequencies. A correlation unit (232-1) generates signals based on a velocity and a range after correlation, the signals being separate for each of the transmission frequencies. An integrating unit (233-1) generates band-synthesized signals based on a velocity and a range after correlation. A target candidate detecting unit (241) performs detection of a target candidate on output signals of the integrating unit (233-1) on the basis of signal strength. A target's relative-velocity/relative-range/arrival-angle calculating unit (242) calculates a relative velocity, a relative range, and an arrival angle of the target candidate.