GNSS Receiver Batch Processing for Autonomous Satellite Initialization
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Solution Overview
Problem
In user satellites, especially those in low Earth orbits or on ascent routes, the simultaneous availability of measurements from at least four navigation satellites is often not possible due to short reception times and long intervals between connections, making it difficult to perform initial position, velocity, and time (PVT) calculations using traditional methods, particularly when the Kalman filter is sensitive to sparse measurements.
Innovation Solution
A receiver with a processing unit that performs batch processing of pseudorange and range rate measurements over a predetermined time period, allowing for initial and continuous PVT calculations without requiring simultaneous availability of four navigation satellites, and uses a Kalman filter for verification, enabling autonomous initialization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional kinematic point solution is used for initial PVT calculation, then the calculation can be performed with available measurements, but it requires simultaneous availability of measurements from at least four navigation satellites which is not possible in LEO or on ascent routes
Solution Approach 1:
The patent segments the measurement data collection process into discrete batches that are accumulated over time. Instead of requiring all four satellite measurements to be available simultaneously, the system divides the requirement into sequential batches, where each batch contributes partial information that is integrated over the predetermined time period to achieve the complete PVT solution.
Solution Approach 2:
The patent implements preliminary action by accumulating and storing measurement batches from available satellites before the complete PVT calculation is performed. The system prepares the data in advance by collecting pseudorange and range rate measurements over time, so that when sufficient data is accumulated, the initial PVT can be calculated without requiring simultaneous four-satellite visibility.
2Ease of operation
If measurements are collected sequentially over time in LEO, then reception is possible despite short time intervals, but the sparse availability of measurements makes the Kalman filter sensitive and less reliable
Solution Approach 1:
The patent merges multiple measurement batches from different time instances into a single integrated batch processing operation. By combining pseudorange and range rate measurements accumulated over the predetermined time period, the system creates a sufficient data set that enables reliable PVT calculation without depending on the continuous performance of the Kalman filter with sparse measurements.
Solution Approach 2:
The patent introduces batch processing as an intermediary mechanism between sparse sequential measurements and the PVT calculation. This intermediary approach accumulates and organizes measurements into complete batches, providing a stable foundation for calculation that reduces the sensitivity to sparse measurement availability and improves overall system reliability.
3Adaptability or versatility
If batch processing is implemented to allow sequential signal reception, then initial PVT calculation becomes possible without simultaneous four-satellite availability, but the processing complexity and computational requirements increase
Solution Approach 1:
The patent implements periodic action by establishing a predetermined time period for accumulating measurement batches. This periodic structure organizes the data collection and processing into regular intervals, making the batch processing operation systematic and manageable. The processing unit activates calculation at defined intervals when complete batches are available, reducing continuous computational burden while maintaining adaptability to LEO conditions.
4Measurement precision
If the predetermined time period for batch processing is extended to accumulate sufficient measurements, then measurement completeness improves, but the time delay in obtaining PVT results increases
Solution Approach 1:
The patent applies parameter changes by optimizing the predetermined time period duration to achieve the best balance between measurement completeness and response time. The system adjusts this critical parameter to ensure sufficient measurements are accumulated for accurate PVT calculation while minimizing the time delay, adapting to the specific orbital conditions and satellite visibility patterns encountered in LEO operations.
Data Source
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AI summary
The invention relates to a receiver for use in a user satellite, located among other things partly or wholly on orbits remote from Earth, for example. The receiver comprises a receiving unit and a processing unit. The receiving unit is configured to receive signals transmitted by navigation satellites of one or more global navigation satellite systems (GNSS). The processing unit is configured to determine measurements based on the data contained in the signals received. The processing unit is further configured to carry out a calculation of position, velocity and time (PVT) based on batch processing of the measurements. The invention further relates to a method and a user satellite.