LEO Satellite Navigation Using Doppler Pseudorange Rate
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Solution Overview
Problem
Current navigation systems rely on Global Navigation Satellite Systems (GNSS) which can be unreliable or unavailable in deep urban areas or during jamming attacks, necessitating an alternative method to correct inertial navigation system (INS) position data.
Innovation Solution
A framework using Low Earth Orbit (LEO) satellite signals for navigation, employing Doppler frequency measurements and extended Kalman filter-based simultaneous tracking and navigation to determine pseudorange rate measurements, correct INS position data, and control vehicle navigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GNSS signals are used for navigation, then navigation accuracy is improved, but reliability deteriorates in deep urban areas or during jamming attacks
Solution Approach 1:
The patent introduces LEO satellite signals as an intermediary navigation source when GNSS signals are unavailable or unreliable. The system uses LEO satellite downlink transmissions as a mediator to provide positioning information in urban canyons and during jamming attacks, bridging the gap between navigation need and signal availability.
Solution Approach 2:
The patent changes the navigation approach from relying on GNSS signals to using LEO satellite signals with different characteristics. By measuring Doppler frequency shifts from LEO satellites and calculating pseudorange rates, the system adapts to different signal environments and maintains navigation capability when GNSS fails.
2Reliability
If LEO satellite signals are used for navigation, then reliability is improved in GNSS-denied areas, but device complexity increases due to additional processing requirements
Solution Approach 1:
The patent makes the navigation system multi-functional by enabling it to operate with both GNSS and LEO satellite signals. The same navigation framework can process different signal types, and the system automatically selects or switches between signal sources based on availability and reliability, reducing the need for separate processing systems.
Solution Approach 2:
The system uses feedback from LEO satellite signal measurements (Doppler frequency and pseudorange rate) to continuously update and correct the navigation solution. This feedback mechanism allows the system to adapt to changing signal conditions and maintain accurate positioning while managing processing complexity through intelligent signal utilization.
3Measurement precision
If INS position data is corrected using LEO satellite measurements, then measurement precision is improved, but loss of time increases due to additional correction calculations
Solution Approach 1:
The patent performs preliminary actions by pre-calculating and storing LEO satellite orbit information and signal characteristics before navigation corrections are needed. The system prepares correction data in advance based on predicted satellite positions and signal parameters, so that when corrections are actually applied, the computational burden is reduced and time loss is minimized.
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 accurate navigation when GNSS signals are unavailable, reducing position estimation errors and maintaining navigation performance by leveraging abundant LEO satellite signals for aiding corrections.
Implementation Method 1
performing a Doppler frequency measurement on received satellite downlink transmissions to determine a pseudorange rate measurement for a vehicle relative to at least one LEO satellite
Data Source
AI summary
Systems, device configurations, and processes are provided for tracking and navigation using low-earth orbit satellite (LEO) signals. Embodiments are provided to track LEO satellites in the absence or during interrupted service by global position sources (e.g., GNSS). Operations and a framework are provided to use low-earth orbit (LEO) downlink transmissions as a source of positioning data. Operations can include performing a Doppler frequency measurement on received satellite downlink transmissions to determine a pseudorange rate measurement for a vehicle relative to at least one LEO satellite. Pseudorange rate measurements may be used to correct vehicle position data of a vehicles inertial navigation system (INS) and for control/navigation of the vehicle. Embodiments allow for simultaneous tracking of LEO satellites and navigation of a vehicle, such as an unmanned aerial vehicle. Embodiments are also directed to employing a propagation model for LEO position and velocity within a simultaneous tracking and navigation (STAN) framework.