Drone RF Frequency Hopping Estimation With RANSAC Outlier Filtering

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Solution Overview

Problem

Current drone detection systems face challenges in accurately identifying frequency hopping parameters from noisy time-frequency samples, especially in multi-target scenarios, due to high implementation complexity and sensitivity to errors, making real-time responses difficult.

Innovation Solution

The implementation of a frequency hopping parameter estimation method based on the Random Sample Consensus (RANSAC) algorithm, which estimates parameters by fitting models to observation data, classifying samples as inliers or outliers, and selecting the best model instance for accurate drone detection, even with limited samples and under error conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional frequency hopping parameter estimation methods are used, then measurement precision may be adequate, but device complexity becomes too high for real-time operation

Engineering Contradiction:
Improvefrequency hopping parameter estimation accuracyVSAvoidimplementation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the frequency hopping parameter estimation process into distinct phases: coarse parameter search followed by fine parameter estimation. The RANSAC algorithm divides the parameter space into manageable segments, estimating parameters iteratively on subsets of data rather than processing all samples simultaneously, thereby reducing computational complexity while maintaining precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by performing coarse parameter estimation before fine parameter estimation. The RANSAC algorithm first identifies candidate parameter sets from a limited number of samples, then refines these estimates using additional samples. This preliminary classification of samples into inliers and outliers enables subsequent precise estimation with reduced computational burden.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If robust error tolerance is implemented, then reliability improves, but device complexity increases

Engineering Contradiction:
Improveerror toleranceVSAvoidalgorithm complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent converts the harmful effect of gross errors and timing errors into a beneficial filtering process. The RANSAC algorithm deliberately introduces random sampling and iterative model fitting, which transforms the presence of outliers into an opportunity to identify and eliminate erroneous data points. By treating errors as identifiable outliers rather than noise to be suppressed, the system achieves high reliability without requiring complex error correction mechanisms.

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

Solution Approach 2:

The patent introduces an intermediary classification step that separates inlier samples from outlier samples before final parameter estimation. This intermediary process acts as a mediator between the noisy observed data and the parameter estimation algorithm, allowing the system to tolerate gross errors and timing errors by processing only the reliable inlier samples in the refinement stage.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If more samples are processed, then measurement precision improves, but loss of time increases

Engineering Contradiction:
Improveparameter estimation accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies partial action by processing a subset of samples rather than all available samples in each iteration. The RANSAC algorithm randomly selects a minimal subset of samples (typically 2-3 samples) to estimate parameters, then evaluates these estimates against the remaining samples. This partial processing approach achieves adequate precision by focusing computational resources on the most informative samples while maintaining real-time processing capability.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent implements periodic action through iterative refinement cycles. The RANSAC algorithm performs multiple iterations of parameter estimation and evaluation, with each iteration processing a small subset of samples. This periodic processing allows the system to accumulate precision improvements over multiple quick iterations rather than requiring a single lengthy processing operation, thereby reducing overall processing time while maintaining high accuracy.

Inventive Principle:
Principle #19Periodic action

Data Source

PatentUS11190233B2Systems and methods for detecting, monitoring, and mitigating the presence of a drone using frequency hopping
Publication Date: 2021.11.30 SKYSAFE INC
  • US11190233B2 patent drawing
  • US11190233B2 patent drawing
  • US11190233B2 patent drawing

AI summary

Systems and methods for detecting, monitoring, and mitigating the presence of a drone are provided herein. In one aspect, a system for detecting presence of a one or more drones includes a radio-frequency (RF) receiver configured to receive an RF signal transmitted between a drone and a controller. The system can further include a processor and a computer-readable memory in communication with the processor and having stored thereon computer-executable instructions to cause the at least one processor to receive a set of samples from the RF receiver for a time interval, the set of samples comprising samples of the first RF signal, obtain a parameter model of the first frequency hopping parameters, and fit the parameter model to the set of samples.