Multiband Radar Pulse Processing for Fine Range Resolution
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Solution Overview
Problem
Conventional radar sensors face challenges in achieving fine range resolution due to the need for high-speed ADCs and DACs, which are bulky and consume high power, making them unsuitable for applications like automotive radar.
Innovation Solution
A radar system that transmits a series of pulse sequences with overlapping frequency bands, each with a bandwidth less than or equal to the maximum sampling frequency of DACs and ADCs, allowing for improved range resolution by computing coarse and fine range estimates using matched filters and modified DFTs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a radar sensor transmits radar signals with a bandwidth greater than 1 GHz to achieve fine range resolution, then range resolution is improved, but ADCs and DACs require greater area and higher power consumption
Solution Approach 1:
The patent divides the total bandwidth into multiple sub-bands, with each sub-band processed by separate ADCs and DACs operating at lower sampling rates. The radar signal is segmented into multiple frequency sub-bands, each handled by dedicated conversion circuits, thereby reducing the sampling rate requirement for each individual converter while maintaining the overall wide bandwidth capability through coherent processing of all sub-bands
Solution Approach 2:
The patent transitions from time-domain processing to frequency-domain processing by applying FFT to the received signals from multiple sub-bands. This dimensional transformation allows the system to achieve fine range resolution through frequency spectrum analysis rather than requiring a single high-speed time-domain converter, effectively moving the resolution achievement from the time dimension to the frequency dimension
2Measurement precision
If a radar sensor transmits radar signals with a bandwidth greater than 1 GHz to achieve fine range resolution, then range resolution is improved, but ADCs and DACs require greater area on an integrated circuit
Solution Approach 1:
The patent segments the wide bandwidth into multiple narrower sub-bands, each processed by separate but smaller ADCs and DACs. This segmentation allows the use of multiple low-speed converters instead of a single high-speed converter, significantly reducing the total integrated circuit area since low-speed converters occupy much less area than high-speed counterparts
Solution Approach 2:
The patent employs frequency-domain processing via FFT to achieve range resolution that would otherwise require high-speed time-domain processing. This dimensional shift from time to frequency domain allows the use of lower-speed, smaller-area converters while maintaining fine range resolution through spectral analysis of the segmented sub-bands
3Measurement precision
If multiple ADCs and DACs are used to process different frequency sub-bands, then range resolution is improved, but device complexity increases
Solution Approach 1:
The patent merges the processing of multiple frequency sub-bands in the frequency domain by applying FFT to each sub-band and then coherently combining the results. This merging approach consolidates the information from multiple ADCs and DACs into a unified range profile, reducing the overall processing complexity compared to handling each sub-band separately in the time domain
Solution Approach 2:
The patent transforms the complex time-domain processing of multiple sub-bands into simpler frequency-domain operations using FFT. This dimensional transformation converts complex time-domain signal mixing and filtering into straightforward frequency-domain multiplication and addition, significantly reducing the computational complexity while achieving fine range resolution
Data Source
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AI summary
A radar sensor system transmits a radar signal that comprises first pulses in a first frequency band and second pulses in a second frequency band. The radar sensor system receives a return of the radar signal from a target, wherein the return comprises the first pulses and the second pulses. The radar sensor system computes a coarse range estimate to the target. Based upon the coarse range estimate, the radar sensor system further computes a fine range estimate to the target, where a resolution of the fine range estimate is based upon a third frequency band that has a bandwidth greater than the first frequency band or the second frequency band.