DME Slant-Range Verification for GNSS Spoofing Detection

Solution Overview

Problem

Existing GNSS systems are vulnerable to spoofing attacks, which can lead to inaccurate position and velocity estimates due to the reliance on complex multi-constellation integration and inertial measurement units (IMUs) that are susceptible to sensor errors and biases, making it difficult to detect sophisticated spoofing techniques.

Innovation Solution

The method involves using distance measuring equipment (DME) transponders to compare real and expected slant ranges from a GNSS receiver's position to known locations, detecting spoofing by identifying significant discrepancies in these ranges, and indicating spoofing when a counter exceeds a threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multi-constellation receivers are used to detect spoofing, then spoofing detection capability is improved, but device complexity increases

Engineering Contradiction:

Improvespoofing detection capabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces DME transponders as intermediary reference points between the GNSS receiver and spoofing detection. By measuring slant ranges to these known ground-based transponders and comparing them with expected ranges calculated from GNSS positions, the system creates an independent verification mechanism that does not require complex multi-constellation integration or IMUs

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical/sensor-based approach (IMUs with accelerometers and gyroscopes) with a radio-based measurement system. Instead of using physical sensors that can drift or be spoofed, the system uses electromagnetic time-of-flight measurements to DME transponders, which are inherently more difficult to spoof and do not suffer from sensor drift

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If inertial measurement units are used to detect spoofing, then spoofing detection capability is improved, but susceptibility to sensor errors increases

Engineering Contradiction:

Improvespoofing detection capabilityVSAvoidsensor accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent introduces DME transponders as intermediary reference points between the GNSS receiver and spoofing detection. By measuring slant ranges to these known ground-based transponders and comparing them with expected ranges calculated from GNSS positions, the system creates an independent verification mechanism that does not require complex multi-constellation integration or IMUs

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical/sensor-based approach (IMUs with accelerometers and gyroscopes) with a radio-based measurement system. Instead of using physical sensors that can drift or be spoofed, the system uses electromagnetic time-of-flight measurements to DME transponders, which are inherently more difficult to spoof and do not suffer from sensor drift

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If P(Y) code signals are used for spoofing protection, then spoofing resistance is improved, but accessibility deteriorates

Engineering Contradiction:

Improvespoofing resistanceVSAvoidsignal accessibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent creates a universal spoofing detection method that works with civilian C/A code signals by incorporating DME transponder measurements. This allows any GNSS receiver with DME capability to perform spoofing detection without requiring access to restricted P(Y) code signals, making the protection mechanism universally applicable to all civilian users

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 detects spoofing by comparing real and expected slant ranges, providing reliable navigation solutions and enabling communication of spoofing events to other vehicles and ground stations, thereby enhancing GNSS integrity.

Implementation Method 1

determining, for each of the subset of DME transponders, a real slant range to the DME transponder

Methodology Applied

Scientific EffectTime of Flight: Time of Flight

Implementation Method 2

calculating an expected slant range to the DME transponder based on a known location of the DME transponder and a reported position of the GNSS receiver

Methodology Applied

Scientific EffectGeometric calculation:

Data Source

PatentUS12461246B2Detecting spoofing in a global navigation satellite system (GNSS) using slant range distance

Publication Date: 2025.11.04 HONEYWELL INTERNATIONAL INC

AI summary

A method for detecting Global Navigation Satellite System (GNSS) spoofing is provided. The method includes receiving signals at a GNSS receiver; processing the signals to determine a calculated position; searching a list of distance measuring equipment (DME) transponders around the calculated position to select a set of DME transponders; sorting the set of DME transponders based on a respective distance between the calculated position and a respective position of each of the DME transponders; selecting a subset of the DME transponders based on the sorting; for each of the subset of the DME transponders, incrementing a counter when a difference between a real slant range, determined by communicating with the DME transponder, and an expected slant range based on height, position and known location of the DME transponder, exceeds a first threshold; and when the counter is greater than a second threshold, indicating that the position is spoofed.