P3-Coded Radar Sidelobe Filtering via Threshold Classification
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Solution Overview
Problem
Existing pulse radar systems using polyphase P3-coded waveforms suffer from false targets due to sidelobes in pulse compression, leading to increased false alarm probabilities and reduced detection capability.
Innovation Solution
A method is proposed to filter out false targets by calculating a target classification threshold based on the fixed distance between the main lobe and sidelobes of the P3 code, comparing signal power at each range cell to this threshold, and classifying locations as sidelobes or main lobes, thereby reducing false alarms without affecting the main lobe's width or signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional window functions are used in pulse compression, then the radar can maintain basic operation, but false targets caused by sidelobes increase and detection capability decreases
Solution Approach 1:
The patent applies local quality by differentiating between main lobe and sidelobe regions through threshold-based classification. By calculating a target classification threshold and comparing signal power at each range cell against this threshold, the system locally identifies and filters sidelobe false targets while preserving main lobe detections, thus improving reliability without sacrificing detection capability
Solution Approach 2:
The patent segments the pulse compression output into distinct regions: main lobe and sidelobe regions. This segmentation is achieved by dividing the range cells into those with power above the classification threshold (main lobe candidates) and those below (sidelobe false targets), allowing independent processing of each region to eliminate false alarms while maintaining valid detections
2Measurement precision
If the pulse width is increased to improve detection, then the main lobe width increases, but the resolution decreases
Solution Approach 1:
The patent applies preliminary action by pre-calculating the target classification threshold based on the known pulse width and the fixed distance characteristic of P3-coded waveforms. This preliminary threshold determination allows the system to proactively identify and filter sidelobe false targets before they can be misinterpreted as real targets, enabling the use of wider pulses for improved detection while maintaining resolution through intelligent filtering
Data Source
AI summary
A method for filtering and removing false targets caused by sidelobes in pulse compression calculates the target filtering threshold to differentiate and eliminate false targets caused by sidelobes in pulse compression. It is applicable in radar signal processing systems using the polyphase P3-coded waveform (the P3 code) for both transmitted and received signals. This method leverages the characteristics of the P3 code's pulse compression output. Specifically, the sidelobes appear symmetrically on both sides of the main lobe, and the distance between the main lobe and the sidelobes is approximately equivalent to the pulse width of the transmitted signal, extending to both sides of the main lobe. For each pulse width of the signal, this distance is fixed and can be predetermined. Experimental results on radar systems have demonstrated that the proposed method effectively filters out all false targets caused by sidelobes in pulse compression.