Radar Ranging Using Distinct Sequences to Reduce Ghost Targets
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Solution Overview
Problem
Digitally-modulated radar systems face issues with ghost targets and sidelobe degradation due to system non-idealities such as phase noise, IQ mismatch, and target movement, which affect the accuracy of range and angle estimation.
Innovation Solution
The method involves transmitting a digitally-modulated signal with a sequence of repeats, where each sequence is different from the others, allowing for preliminary target estimation and final estimation to reduce the impact of ghosting and sidelobe degradations by canceling out imperfections in transmitters and receivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the same sequence is repeatedly transmitted to improve signal strength, then the signal coverage is improved, but ghost targets and sidelobe degradation increase due to system non-idealities
Solution Approach 1:
The patent divides the transmitted signal into multiple different sequences (e.g., first sequence, second sequence, third sequence) instead of repeating the same sequence. Each sequence is processed separately through preliminary target estimation, and the results are combined for final target estimation. This segmentation approach allows the system to maintain signal strength while reducing ghost targets and sidelobe degradation by preventing the repetition of identical signal patterns that cause interference.
2Measurement precision
If multiple different sequences are transmitted to reduce ghosting and sidelobe degradation, then the accuracy of target estimation is improved, but the transmission time and processing complexity increase
Solution Approach 1:
The patent performs preliminary target estimation for each sequence before combining the results for final target estimation. This preliminary action allows the system to process each sequence efficiently and independently, then combine the results to achieve accurate target estimation. By performing preliminary estimation for each sequence separately, the system can reduce overall processing time and complexity while maintaining high measurement precision through the combination of multiple different sequences.
Data Source
AI summary
A method of radar ranging comprises transmitting a digitally-modulated signal comprising successively in time, for each sequence in a plurality N of sequences, a plurality M+1 of repeats of said sequence, wherein each said sequence consists of a plurality Lc of digitally-modulated chips, wherein at least one sequence in the plurality of sequences is different from another sequence in said plurality of sequences; receiving a version of the digitally-modulated signal reflected scattered by one or more physical targets; for each sequence in the plurality of sequences, performing a preliminary target estimation; and using each said preliminary target estimation for all sequences in the plurality of sequences, performing a final target estimation.