Satellite Navigation Accelerometer Doppler Rate Extraction
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Solution Overview
Problem
Current GNSS receivers are unable to accurately determine a user's absolute acceleration/deceleration due to the weak Doppler rate of GNSS signals and inadequate baseband signal processing techniques, which introduce noise and limit the accuracy of Doppler frequency change estimation.
Innovation Solution
The system receives signals from multiple satellites, extracts Doppler rate measurements using baseband signal processing, determines satellite positions and acceleration/deceleration, and calculates the user's absolute acceleration/deceleration using direction cosine vector projections and Doppler rates, enabling more accurate navigation solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current baseband signal processing techniques are used with typical coherent integration time of 20 ms, then the processing is computationally manageable, but the Doppler frequency change of LOS GNSS signals cannot be recognized and extra additive noise power is introduced to estimates
Solution Approach 1:
The patent changes the coherent integration time parameter from the typical 20 ms to a longer duration (e.g., 100 ms or more), enabling the baseband signal processing to recognize and measure the Doppler frequency change of LOS GNSS signals. This parameter change allows the system to overcome the limitation of current processing techniques while maintaining computational feasibility through optimized algorithms.
2Measurement precision
If differencing between-epoch Doppler measurements is used to estimate Doppler frequency change, then an estimate can be obtained, but extra additive noise power is introduced to the estimates
Solution Approach 1:
The patent extracts the Doppler rate measurement directly from the baseband signal processing output without performing differencing operations between epochs. By taking out the desired measurement (Doppler rate) directly from the processed signal, the system avoids introducing extra additive noise power that would result from differencing operations, thereby maintaining higher estimation accuracy.
3Measurement precision
If current GNSS receivers are used, then basic positioning functionality is provided, but absolute acceleration/deceleration cannot be determined due to weak Doppler rate
Solution Approach 1:
The patent performs preliminary baseband signal processing to extract Doppler rate measurements before using them for acceleration calculation. By performing this preliminary extraction and preservation of Doppler rate information, the system overcomes the limitation of current receivers that lose this information, enabling accurate determination of user absolute acceleration/deceleration.
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 the accuracy of Doppler frequency change estimation and user acceleration/deceleration calculations, improving navigation performance by reducing noise and extending coherent integration time for better signal processing.
Implementation Method 1
GNSS systems rely on signals from multiple satellites to determine a GNSS receiver's location. Unfortunately, such signals are subject to the Doppler effect, and this has been known to introduce errors.
Data Source
AI summary
Systems and methods for determining a user's absolute acceleration/deceleration on an Earth based reference frame. Signals from multiple satellites are received and the Doppler rate for each satellite is extracted using baseband signal processing. Then, using each satellite's ephemeris, the acceleration/deceleration and Earth frame position of each satellite is determined. The user's absolute position is then used, along with each satellite's position to calculate direction cosine vector projections for each satellite. The user's absolute acceleration/deceleration is then calculated using the various direction cosine vector projections, the various satellite acceleration/deceleration values, and each satellite's Doppler rates. The resulting absolute acceleration/deceleration can then be used for more accurate navigation solutions.