Radar Device Noise Detection via Signal Segmentation

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Solution Overview

Problem

Radar devices face a deterioration in detection accuracy due to electromagnetic noise interference, which affects the correction of beat signals used for target detection, leading to false target detection issues.

Innovation Solution

A radar device that intermittently and repeatedly transmits frequency-modulated signals, allowing for the separation of beat signals generated during transmission and reception periods, enabling the detection of electromagnetic noise and accurate target detection by calculating noise frequencies and Doppler frequencies separately from the observation target frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electromagnetic noise correction is performed using the spectrum of beat signal obtained in reception mode, then false detection of targets is prevented, but detection accuracy deteriorates when electromagnetic noise is input to the AD converter

Engineering Contradiction:

Improvefalse detection preventionVSAvoiddetection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent divides the noise correction process into two separate stages: first obtaining the noise spectrum during transmission mode when no reflection wave is present, then using this noise spectrum to correct the beat signal spectrum obtained during reception mode. This segmentation allows distinct handling of noise characteristics and target signal characteristics, preventing noise from affecting target detection accuracy while still eliminating false detections.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs noise spectrum measurement in advance during transmission mode, before processing the reception mode signals. By capturing the electromagnetic noise characteristics when the AD converter is active but no reflection wave is present, the system prepares a noise reference that can be subtracted from the reception mode beat signal spectrum, thereby correcting noise interference without compromising target detection accuracy.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If the AD converter samples the beat signal at high frequency, then detection resolution is improved, but electromagnetic noise within the sampling band is amplified

Engineering Contradiction:

Improvedetection resolutionVSAvoidelectromagnetic noise

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful electromagnetic noise into a useful reference by measuring its spectrum during transmission mode when no reflection wave is present. This noise spectrum is then used to correct the reception mode beat signal spectrum, transforming the previously harmful noise into a known quantity that can be mathematically removed. This approach allows high-frequency sampling for improved resolution while systematically eliminating noise that would otherwise be amplified.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 effectively suppresses the deterioration of detection accuracy caused by electromagnetic noise, allowing for precise observation target detection even in noisy conditions.

Implementation Method 1

a frequency-modulated signal, whose frequency changes with passage of time

Methodology Applied

Scientific EffectFrequency modulation: Phase Modulation

Implementation Method 2

a mixer generates the beat signal by mixing the reception signal and the local signal, and an analog-to-digital (AD) converter converts the beat signal generated by the mixer into a digital signal

Methodology Applied

Scientific EffectMixing: Heterodyne

Implementation Method 3

calculating each of a frequency of the electromagnetic noise input and a Doppler frequency that corresponds to a relative velocity with respect to a source of the electromagnetic noise

Methodology Applied

Scientific EffectDoppler effect: Doppler Effect

Data Source

PatentUS11921196B2Radar device, observation target detecting method, and in-vehicle device

Publication Date: 2024.03.05 MITSUBISHI ELECTRIC CORP

AI summary

A radar device includes: an electromagnetic noise detecting unit for detecting electromagnetic noise input to an ADC using digital data in a period when no radar signal is transmitted, among digital data output from the ADC; and an observation target detecting unit for detecting an observation target using digital data in a period when the radar signal has been transmitted, among the digital data output from the ADC, and the electromagnetic noise detected by the electromagnetic noise detecting unit.