Stepped Pulse Digitally Modulated Radar for Automotive Range Resolution
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Solution Overview
Problem
Conventional radar sensors with large bandwidth signals for high range resolution require high-speed analog-to-digital converters (ADCs) and digital-to-analog converters (DACs), leading to increased size and power consumption, making them bulky and inefficient for applications like automotive radar.
Innovation Solution
A radar sensor that transmits a digitally modulated signal using a stepped series of pulse sequences with overlapping frequency bands, allowing for a collective bandwidth greater than individual pulse bandwidths, thus reducing the sampling rate requirements for ADCs and DACs and achieving improved range resolution without the need for high-speed converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a radar signal with large bandwidth (greater than 1 GHz) is transmitted to achieve fine range resolution, then range resolution is improved, but ADCs and DACs require greater sampling rates which increase area and power consumption
Solution Approach 1:
The patent divides the large bandwidth signal into multiple smaller bandwidth pulse sequences, each with bandwidth less than or equal to the sampling rate of the ADCs and DACs. By segmenting the total bandwidth B into N sequences with individual bandwidths B1, B2, ..., BN (where each Bi ≤ Fs/2), the system achieves the cumulative bandwidth effect without requiring converters with sampling rates greater than Fs, thereby reducing power consumption while maintaining fine range resolution.
2Measurement precision
If a radar signal with large bandwidth (greater than 1 GHz) is transmitted to achieve fine range resolution, then range resolution is improved, but ADCs and DACs require greater sampling rates which increase area on integrated circuit
Solution Approach 1:
The patent segments the large bandwidth requirement into multiple smaller bandwidth pulse sequences that can be handled by lower-speed ADCs and DACs. Each sequence has bandwidth Bi ≤ Fs/2, allowing the use of smaller, lower-power converters with sampling rate Fs, thereby reducing the total area on the integrated circuit while still achieving the desired fine range resolution through the cumulative bandwidth of all sequences.
3Measurement precision
If conventional radar sensors use high-speed ADCs and DACs to handle large bandwidth signals, then range resolution is improved, but the radar sensor becomes bulky
Solution Approach 1:
The patent divides the large bandwidth signal into multiple smaller bandwidth pulse sequences, each compatible with lower-speed ADCs and DACs having sampling rate Fs. By using N sequences with individual bandwidths less than or equal to Fs/2, the system employs smaller, lower-speed converters that reduce the overall volume of the radar sensor, making it more compact while maintaining fine range resolution through the aggregate bandwidth of all sequences.
Data Source
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 concatenates the first pulses and the second pulses, and computes an estimated range to a target based upon a Fourier transform of the concatenated first and second pulses. A range resolution of the estimated range is based upon a bandwidth of a third frequency band that includes the first frequency band and the second frequency band.