Passive Object Tracking via Bistatic Dual-Polarization Receivers

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Solution Overview

Problem

Radar systems face challenges in detecting and tracking moving objects equipped with radar jammers, such as DRFM jammers, which generate fake targets that overwhelm the radar system, making it difficult to distinguish actual targets from false ones.

Innovation Solution

The method involves using bistatic dual-polarization receivers to separate polarization-based components from received signals, leveraging the modulation of polarization caused by the object's motion to determine its location, orientation, and speed, even when the object is equipped with a jammer. This is achieved by receiving signals from dual-polarized antennas spaced apart and computing the time difference to maximize correlation, allowing for accurate tracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a DRFM jammer is deployed on a moving object, then the radar system is inundated with fake targets making detection difficult, but the polarization of the transmitted signal remains modulated by the object's motion which can be used for tracking

Engineering Contradiction:

Improvetracking reliabilityVSAvoidtarget detection difficulty

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent converts the harmful jamming signal into a beneficial tracking resource by exploiting the polarization modulation inherent in the transmitted signal. Instead of treating the DRFM jammer's fake targets as pure interference, the system uses the polarization characteristics of the transmitted signal to passively track the moving object carrying the jammer, turning the adversary's weapon into a tracking beacon.

Inventive Principle:

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

Solution Approach 2:

The patent changes the parameter space for detection by moving from intensity-based detection (which is overwhelmed by jamming) to polarization-based detection. By analyzing the polarization state of the received signal rather than its amplitude, the system can extract tracking information that is insensitive to the jamming intensity and fake target generation.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional radar receivers are used to detect transmitted signals, then the system is simple and cost-effective, but it cannot distinguish actual targets from fake targets generated by jammers

Engineering Contradiction:

Improvesystem implementation easeVSAvoidtarget identification precision

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent introduces polarization analysis as an intermediary mechanism between the received signal and target identification. By adding polarization detection capability to conventional receivers, the system gains the ability to distinguish true targets from fake ones without completely replacing the existing receiver architecture, thus maintaining ease of implementation while improving identification precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If the receiver attempts to filter out jamming signals to improve target detection, then false target recognition may improve, but the polarization modulation information carried by the transmitted signal may be lost

Engineering Contradiction:

Improvetarget discrimination precisionVSAvoidpolarization modulation information loss

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent inverts the conventional approach by not filtering out the jamming signal but rather using it directly for tracking. Instead of removing the problematic signal components, the system exploits the polarization modulation present in the transmitted signal to extract tracking information, thereby avoiding information loss while achieving target discrimination.

Inventive Principle:

Principle #13The other way round (Inversion)

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 passive tracking of moving objects, including those with radar jammers, by utilizing conventional radar receivers and additional hardware/software to compute polarization-based components, effectively countering jamming threats and providing accurate location, orientation, and speed data.

Implementation Method 1

separating a polarization-based component of the received signal from a non-polarization-based component thereof

Methodology Applied

Scientific EffectPolarization: Polarisation

Implementation Method 2

The frequency of the reflected signal may be different from that of the transmitted signal due to the Doppler effect, where the change in the frequency is related to the speed of the moving object

Methodology Applied

Scientific EffectDoppler effect: Doppler Effect

Data Source

PatentUS10451709B1Passive tracking of objects using bistatic dual-polarization receivers

Publication Date: 2019.10.22 QUALCOMM INC

AI summary

A system for detecting and/or tracking a moving object uses signals received from the object at two or more receivers, each of which is dual polarized. At each receiver, the component of the received signal associated with the polarization thereof is separated from the non-polarization-based component, and the modulation of the polarization-based component is used for locating and/or tracking the moving object.