Sub-Nyquist HFM Chirp Radar for Range-Doppler Estimation
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Solution Overview
Problem
Existing radar technologies face challenges in achieving precise range and Doppler estimation due to range-Doppler coupling, high sampling rate requirements, and range ambiguity, especially in scenarios involving multiple targets, which can lead to erroneous target tracking and increased costs for high-rate analog-to-digital converters.
Innovation Solution
The use of hyperbolic frequency modulated (HFM) chirp pulses sampled below the Nyquist rate to exploit unique aliasing phenomena, allowing for accurate range and Doppler frequency determination without additional filtering, such as match filtering, by leveraging the distinct aliases created by HFM pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional radar sampling at Nyquist rate is used, then accurate range and Doppler estimation can be achieved, but high sampling rate requirements increase system cost and complexity
Solution Approach 1:
The patent converts the harmful aliasing effect that normally degrades radar measurement accuracy into a beneficial phenomenon. By deliberately sampling HFM chirp pulses below the Nyquist rate, the system generates distinct aliases that can be used to accurately determine both range and Doppler frequency. The unique property of HFM pulses is that their aliases contain sufficient information to resolve the original signal parameters, thus transforming what is typically a source of error into a useful measurement mechanism that reduces sampling rate requirements.
Solution Approach 2:
The patent changes the sampling rate parameter from the conventional Nyquist rate to a sub-Nyquist rate. This parameter change is made possible by the specific properties of HFM chirp pulses, which maintain measurement accuracy even when sampled below the traditional Nyquist threshold. This parameter change directly reduces the complexity and cost of the analog-to-digital converter while preserving the ability to accurately estimate range and Doppler frequency.
2Measurement precision
If match filtering is applied to resolve range-Doppler coupling, then measurement precision improves, but device complexity and processing overhead increase
Solution Approach 1:
Instead of using complex match filtering to resolve range-Doppler coupling, the patent exploits the aliasing phenomenon generated by sub-Nyquist sampling of HFM pulses. The aliases naturally contain decoupled range and Doppler information that can be extracted through simpler processing. This approach converts the harmful aliasing effect into a beneficial source of decoupled measurement data, eliminating the need for computationally intensive match filtering while maintaining or improving measurement accuracy.
Solution Approach 2:
The patent extracts the useful range and Doppler information directly from the aliased signal components without requiring full match filtering processing. By recognizing that the aliases of HFM pulses contain the necessary measurement information, the system extracts the required parameters through simplified processing steps, removing the need for complex filtering operations and reducing overall system complexity.
3Measurement precision
If high-rate analog-to-digital converters are used, then sampling accuracy improves, but system cost increases
Solution Approach 1:
The patent converts the typically harmful aliasing effect into a beneficial mechanism that enables accurate measurement with lower-cost, lower-rate analog-to-digital converters. By deliberately sampling HFM chirp pulses below the Nyquist rate, the system generates aliases that still contain sufficient information for accurate range and Doppler estimation. This approach allows the use of cheaper, lower-performance converters while maintaining measurement accuracy, thus reducing system cost without sacrificing precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables cost-effective and accurate range and Doppler estimation in radar systems, improving target detection and tracking, particularly in complex scenarios with multiple targets, while reducing the need for high-rate sampling and expensive converters.
Implementation Method 1
receiving a second signal, the second signal being a signal resulting from reflection of the first signal by at least one target
Implementation Method 2
exploiting unique aliasing phenomenon incurred by HFM pulses
Data Source
AI summary
Some non-limiting embodiments of the present disclosure relate to transmitting and/or receiving of sensing. A waveform of a hyperbolic frequency modulated (HFM) chirp pulse in a frequency range is obtained. A first signal including a plurality of HFM chirp pulses is transmitted. A second signal is received, wherein the second signal is a signal resulting from reflection of the first signal by at least one target. A subsampled first signal is obtained by sampling the first signal at a sampling frequency fS below a Nyquist rate fnyq. A subsampled second signal is obtained by sampling the second signal at the sampling frequency fS. A range of the at least one target and/or a Doppler frequency is determined by processing of the subsampled first signal and the subsampled second signal.