Mobile Radar Target Detection Using Carrier-Fixed Grid Shifting
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Solution Overview
Problem
Detecting small targets with low radar cross-section in radar clutter is challenging for mobile platforms due to difficulties in setting detection thresholds and aligning pre-detections across successive antenna revolutions, leading to high false alarm rates and reduced sensitivity.
Innovation Solution
A method using a fixed storage grid with azimuth and distance increments defined by possible target movements, applying the 'track before detect' principle, where pre-detections are shifted and stored in cells centered on the radar's initial position, and detections are confirmed by linear regression and variance analysis, reducing false alarms and processing power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high detection threshold is set to avoid detecting unwanted spikes, then false alarm rate is reduced, but detection sensitivity decreases and targets are not detected
Solution Approach 1:
The patent applies preliminary action by performing pre-detection processing and stability testing across multiple antenna revolutions before final detection. The system accumulates pre-detections over N revolutions, tests their stability, and only then confirms them as valid detections. This preliminary accumulation and validation process allows the use of higher thresholds while maintaining sensitivity, as true targets are confirmed through temporal consistency rather than relying solely on single-pulse amplitude.
Solution Approach 2:
The patent implements continuity of useful action by continuously accumulating pre-detections over multiple antenna revolutions and maintaining a running stability test. Rather than making discrete detection decisions on individual pulses, the system continuously updates the detection state by integrating information across N revolutions, ensuring that true targets are detected while transient clutter is filtered out through the continuous stability assessment.
2Ease of operation
If pre-detections are integrated in Cartesian coordinates with fixed integration cells, then processing is simplified, but detection performance becomes non-uniform due to variable cell-to-resolution-cell ratios
Solution Approach 1:
The patent applies local quality by making the integration cell dimensions adaptive rather than fixed. The integration cells are defined with azimuth and distance increments that are locally adapted to the radar resolution at each range cell. This means that cells closer to the radar have different dimensions than cells farther away, with the cell size scaling with range to maintain a consistent ratio between integration cells and resolution cells throughout the scanning space, thereby ensuring uniform detection performance across all ranges.
3Measurement precision
If detection threshold is set low to detect all potential targets, then detection sensitivity is improved, but false alarm rate increases as targets are buried among unwanted spikes
Solution Approach 1:
The patent uses preliminary action by accumulating pre-detections over multiple revolutions before making a final detection decision. The system sets a relatively low threshold to capture potential targets, then applies a stability test across N revolutions to filter out false alarms. True targets that consistently appear at the same position across multiple revolutions are confirmed, while transient clutter spikes that do not persist are rejected. This two-stage approach with preliminary accumulation allows sensitive detection while maintaining low false alarm rates.
4Measurement precision
If position measurements are performed using azimuth and distance in polar coordinates, then measurement accuracy is improved, but aligning pre-detections across successive antenna revolutions becomes difficult due to carrier movement
Solution Approach 1:
The patent introduces an intermediary reference frame that is fixed to the radar carrier position. Instead of directly comparing polar coordinates from different revolutions (which are affected by carrier movement), the system transforms all pre-detections into this carrier-fixed reference frame. This intermediary frame acts as a mediator that absorbs the carrier motion effects, allowing stable alignment and integration of pre-detections across multiple revolutions. The reference frame moves with the carrier, automatically compensating for platform motion without requiring complex real-time transformations.
Data Source
AI summary
A method for detecting targets using a mobile radar having a rotary antenna, notably small targets buried in radar clutter, without increasing the number of false detections, includes determining pre-detections during N antenna revolutions, including determining pre-detections revolution by revolution, each pre-detection being stored in a grid of cells centered on the position that the radar occupied at the start of the current revolution, each grid cell corresponding to an azimuth range and a distance range. This step also includes, at the end of each revolution, a step of shifting all the pre-detections stored in the grid during the previous revolutions by the movement undergone by the radar during the last revolution. The method also includes determining detections, a target being detected from the moment that a set of pre-detections stored in the grid has its distances to the radar which constitute a linear progression during the N antenna revolutions.