Nonlinear FMCW Chirp Design for High-Speed Target Resolution

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Solution Overview

Problem

Conventional FMCW radar systems using linear long chirp signals face interference issues, reduced signal-to-noise ratio (SNR), and difficulty in detecting high-speed objects due to signal spreading and blurring, leading to reduced resolution and obscured detection of nearby objects.

Innovation Solution

Employing non-linear long chirp signals that change frequency non-linearly over time, combined with non-equidistant sampling of the demodulated signal, to maintain full SNR and improve resolution for both stationary and high-speed objects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If linear long chirp signals are used in FMCW radar systems, then the radar can detect objects over a longer duration, but the signal-to-noise ratio is reduced and resolution deteriorates due to signal spreading and blurring

Engineering Contradiction:

Improvechirp signal durationVSAvoiddetection resolution

Core Design Contradiction:

Duration of action of moving objectVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by transitioning from linear chirp signals to non-linear chirp signals with specifically designed frequency trajectories. The non-linear frequency modulation law is optimized to compensate for signal spreading effects, maintaining both long duration and high resolution by dynamically adjusting the frequency sweep rate throughout the chirp duration.

Inventive Principle:

Principle #35Parameter changes

2Area of stationary object

If linear long chirp signals are used, then detection coverage is extended, but interference issues increase and SNR is reduced

Engineering Contradiction:

Improvedetection coverageVSAvoidinterference and noise

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent changes the fundamental parameter of chirp signal modulation from linear to non-linear, designing specific frequency trajectory parameters that extend detection coverage while simultaneously reducing susceptibility to interference and noise through optimized signal characteristics.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If conventional linear chirp signals are used, then the radar system operates with simple signal processing, but high-speed objects suffer from signal spreading causing blurring and reduced detection accuracy

Engineering Contradiction:

Improvesignal processing complexityVSAvoidhigh-speed object detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces non-linear frequency modulation parameters to the chirp signal, which compensates for the Doppler effect and signal spreading caused by high-speed targets. This parameter change maintains detection accuracy for high-speed objects while keeping the overall system complexity manageable through established signal processing techniques.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20260009881A1Non-linear chirp signal to mitigate signal-to-noise ratio reduction in FMCW radar

Publication Date: 2026.01.08 NXP BV

AI summary

A radar system employs one or more radar sensors to obtain a sensing result (i.e., information about at least one object). The one or more radar sensors generate and transmit one or more chirp signals and in response to receiving the reflected chirp signal determine the sensing result. The radar system includes one or more radar sensors that employ a non-linear long chirp signal with a logarithmic phase.