Doppler-Based Position Determination Without Time-of-Flight
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Solution Overview
Problem
Existing satellite navigation methods for determining a vehicle's position rely on time-of-flight measurements, which can lead to errors due to ionospheric and multipath effects, limiting accuracy and safety when combined with velocity data from Doppler measurements.
Innovation Solution
A method using only Doppler measurements to determine a vehicle's position independently of time-of-flight measurements, allowing for precise position calculation without error propagation from time-of-flight-based solutions, and optionally incorporating time-of-flight measurements for clock error calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time-of-flight measurements are used to determine position, then position can be calculated, but accuracy deteriorates due to ionospheric and multipath effects
Solution Approach 1:
The invention extracts and removes the harmful time-of-flight measurement component from the position determination process. By using only Doppler measurements from satellite signals to calculate position, the method eliminates the propagation of ionospheric and multipath errors that affect time-of-flight-based solutions, thereby improving position accuracy independent of velocity measurements.
Solution Approach 2:
The invention segments the satellite navigation measurement process into independent components: Doppler measurements for position determination and separate velocity calculations. This segmentation allows position to be determined independently without being coupled to velocity measurements from the same time-of-flight data, reducing error propagation in data fusion applications.
2Reliability
If both position and velocity are determined from the same time-of-flight and Doppler measurements, then complete navigation information is available, but reliability deteriorates due to correlated errors
Solution Approach 1:
The invention extracts the Doppler measurement component specifically for position determination, separating it from the time-of-flight measurements used for velocity. This extraction creates independent position and velocity solutions with uncorrelated errors, improving reliability for data fusion applications while maintaining complete navigation information.
3Device complexity
If four satellites are used for position determination via time-of-flight measurements, then position can be calculated, but device complexity increases when additional satellites are needed for Doppler-based position
Solution Approach 1:
The invention makes Doppler measurements serve multiple functions: they provide both velocity information and independent position determination. By utilizing the frequency shift information from satellite signals, the system can calculate position without relying on time-of-flight measurements, reducing the number of satellites needed while improving accuracy and independence of the position solution.
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 enhances accuracy and safety by reducing ionospheric and multipath effects, providing independent solutions for position and velocity, and requiring fewer satellites when stationary, thus improving data fusion performance.
Implementation Method 1
performing a plurality of Doppler measurements on the satellite signals, in the process producing a first Doppler value on the basis of the first satellite signal, a second Doppler value on the basis of the second satellite signal, a third Doppler value on the basis of the third satellite signal, and a fourth Doppler value on the basis of the fourth satellite signal
Data Source
AI summary
A method for determining a position of a unit by satellite navigation, wherein the position is determined solely by Doppler measurements. Further, an associated control module and an associated data storage medium are disclosed.