Sliding Window Integration for Radar Object Detection
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Solution Overview
Problem
Radar systems face a tradeoff between frame duration and frame refresh rate, with longer frame duration limiting the radar duty cycle due to heat dissipation, making it challenging to detect objects effectively.
Innovation Solution
A sliding window integration scheme is implemented, where multiple sub-frames with gaps are used within a frame, processing reflections using an on-off Radon transform to correct phase bias and integrate chirps, resulting in a longer frame duration without reducing the frame refresh rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the frame duration is increased to improve object detection accuracy, then the detection accuracy is improved, but the frame refresh rate decreases
Solution Approach 1:
The frame is segmented into multiple sub-frames with gap durations between them. Each sub-frame contains a portion of the linear frequency modulated signals, and the gaps allow for heat dissipation. This segmentation enables the system to achieve the benefits of longer integration time while maintaining the ability to refresh frames frequently by processing sub-frames independently and combining their results through the on-off Radon transform.
2Length of stationary object
If the frame duration is extended to improve detection range, then the detection range is improved, but the radar duty cycle is limited due to heat dissipation
Solution Approach 1:
The radar transmission follows a periodic pattern with alternating transmission periods (sub-frames) and gap periods (no transmission). This periodic action allows the radar to transmit signals for extended total duration while periodically stopping to dissipate heat. The on-off Radon transform is specifically designed to handle this periodic transmission pattern and correct the phase bias introduced by the gap durations, enabling coherent integration across multiple sub-frames to extend detection range without excessive heat accumulation.
3Duration of action of moving object
If multiple sub-frames with gaps are used to increase frame duration, then the frame duration is increased, but phase bias is introduced that degrades signal quality
Solution Approach 1:
The on-off Radon transform applies a preliminary correction to counteract the phase bias that would otherwise be introduced by the gap durations between sub-frames. By calculating and applying the appropriate phase correction factor before integrating the signals from multiple sub-frames, the system prevents the degradation of signal quality that would result from the discontinuous transmission pattern. This preliminary anti-action ensures that the extended frame duration does not compromise measurement precision.
Data Source
AI summary
A system and method to detect an object with a radar system involve transmitting two or more sets of linear frequency modulated signals with a gap duration Dg, during which there is no transmission, between each of the two or more sets of the linear frequency modulated signals. Each of the two or more sets of the linear frequency modulated signals defines a sub-frame, and two or more sub-frames defines a frame. The method includes receiving reflections resulting from the linear frequency modulated signals encountering one or more objects in a field of view of the radar system, and processing the reflections to identify the one or more objects. The processing includes performing an on-off Radon transform to correct a phase bias caused by the gap duration during which there is no transmission.