Non-Linear FMCW Chirp Signals for High-Speed Target Detection

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Solution Overview

Problem

Conventional FMCW radar systems face interference issues due to multiple chirp signals, leading to reduced signal-to-noise ratio (SNR) and resolution, especially when detecting high-speed objects, which obscures stationary or slower-moving objects and limits detection range.

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

1Adaptability or versatility

If multiple chirp signals are transmitted per radar frame, then detection coverage is improved, but signal-to-noise ratio and resolution are reduced due to interference

Engineering Contradiction:
Improvedetection coverageVSAvoidsignal-to-noise ratio
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent implements a frame-based periodic transmission structure where chirp signals are sent in organized radar frames with specific timing intervals. This periodic action allows multiple chirp signals to be transmitted while maintaining temporal separation that reduces interference, thus preserving signal-to-noise ratio while expanding detection coverage across multiple targets.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent employs dynamic chirp signal parameters including variable sweep widths and adjustable timing intervals between chirp signals within a frame. By dynamically adapting the frequency sweep characteristics and transmission timing, the system optimizes detection coverage for multiple objects while maintaining adequate signal-to-noise ratio through controlled temporal and spectral separation.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If multiple chirp signals are transmitted per radar frame, then detection coverage is improved, but resolution is reduced due to interference

Engineering Contradiction:
Improvedetection coverageVSAvoidresolution
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The periodic frame structure with controlled chirp signal timing enables multiple signals to be transmitted while maintaining resolution through adequate temporal separation. Each chirp signal within a frame is transmitted at distinct time intervals, preventing signal overlap and preserving the ability to resolve closely spaced targets.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts chirp signal parameters such as sweep width and timing to maintain resolution when detecting multiple objects. By adaptively controlling the temporal and spectral characteristics of each chirp signal within a frame, the system preserves measurement precision while expanding detection coverage.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If conventional linear chirp signals are used, then system complexity is low, but high-speed objects are obscured and detection range is limited

Engineering Contradiction:
Improvesignal generation complexityVSAvoiddetection capability
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent transitions from conventional linear chirp signals to non-linear chirp signals with specifically designed frequency-time characteristics. This parameter change in the signal waveform enables the system to track and detect high-speed objects effectively while maintaining manageable system complexity through established signal generation techniques adapted for non-linear frequency modulation.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4675306A1Non-linear chirp signal to mitigate signal-to-noise ratio reduction in FMCW radar
Publication Date: 2026.01.07 NXP BV
  • EP4675306A1 patent drawingFigure 1
  • EP4675306A1 patent drawingFigure 2
  • EP4675306A1 patent drawingFigure 3

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.