HF Positioning via Ionospheric Altitude Characterization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for accurate positioning, such as GNSS, are unreliable during Anti-Access Area Denial (A2AD) conditions and over featureless terrain, and traditional HF positioning techniques like Loran are inaccurate due to ionospheric variations and lack of global coverage.
Innovation Solution
A system using a multi-channel HF receiver and inertial navigation system to determine position by analyzing HF timing signals, accounting for ionospheric refraction and variations, with a memory-based approach to update ionospheric altitudes and calculate precise positioning solutions without GNSS signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional HF positioning methods are used, then positioning can be performed without GNSS, but positioning accuracy deteriorates due to ionospheric variations and refraction
Solution Approach 1:
The system dynamically adjusts ionospheric altitude parameters based on time, date, and position data. By changing the ionospheric model parameters to reflect actual conditions rather than using fixed values, the system compensates for ionospheric variations and improves positioning accuracy while maintaining reliability in GNSS-denied environments
Solution Approach 2:
The system uses feedback from multiple HF signal measurements and ionospheric observations to continuously refine positioning calculations. By incorporating feedback loops that adjust for measured ionospheric delays and refraction effects, the system maintains accurate positioning despite ionospheric variability
2Area of stationary object
If HF signals are used for positioning, then global coverage is achieved, but signal reliability worsens due to ionospheric refraction and fluctuations
Solution Approach 1:
The system employs dynamic ionospheric modeling that adapts to changing conditions in real-time. By making the ionospheric parameters dynamic rather than static, the system can track and compensate for ionospheric fluctuations, maintaining signal reliability across global coverage areas despite varying ionospheric states
Solution Approach 2:
The system performs preliminary characterization of ionospheric conditions using historical data and predictive models before actual positioning measurements. By anticipating ionospheric behavior patterns based on time, date, and location, the system prepares compensation parameters in advance, improving signal reception reliability before measurements are taken
3Device complexity
If single frequency HF signals are used, then system complexity is reduced, but positioning reliability deteriorates due to ionospheric variations at different frequencies
Solution Approach 1:
The system segments the HF signal reception into multiple frequency channels, processing each frequency separately to measure different ionospheric effects. By dividing the measurement process into frequency-specific segments, the system can isolate and compensate for frequency-dependent ionospheric variations, improving positioning reliability without excessive complexity
Solution Approach 2:
The system uses multiple HF frequencies with a single integrated processing framework that handles all frequencies universally. By designing the receiver and processing system to universally handle multiple frequencies through a common architecture, the system achieves frequency diversity benefits for reliability while maintaining manageable system complexity through shared components
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
Enables accurate and passive HF positioning worldwide, reducing navigation errors and providing reliable positioning in areas without GNSS coverage by characterizing ionospheric undulations and using a novel approach to determine refraction altitudes and timing errors.
Implementation Method 1
the path the HF signals may follow as refracted from the random fluctuating level of the ionosphere
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A system and method for HF positioning characterizes the undulations of the ionosphere in real-time to determine the refraction altitude of a specific HF frequency at a specific time of day at a specific position. The system accounts for the seasonal (summer, winter) and daily (daylight, night, grey-line transition) variations of the ionosphere determining a highly accurate timing error relative to a timing reference (118). The system employs a novel approach that is capable of passively and accurately determining a position anywhere in the world without use of a GNSS signal receiving known-time transmissions of narrow band HF timing signals refracted via ionospheric skywave.