Pseudolite RTK Positioning for Indoor Signal Obstruction
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Solution Overview
Problem
Existing RTK positioning methods face challenges in accurately determining user location in areas where satellite signals are obstructed or unavailable, such as indoors or in mountainous regions, due to signal interference and geometry changes, leading to errors in carrier phase positioning.
Innovation Solution
The implementation of a pseudolite-based RTK positioning system, which uses multiple pseudolites and reference stations to determine the user's location, allowing for continuous signal reception and accurate positioning with errors of several mm to cm, even in areas where GPS signals are unavailable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If GPS satellite signals are used for positioning, then positioning can be performed outdoors with high accuracy, but positioning cannot be performed in hidden locations such as indoors, mountains, forests, or among skyscrapers where satellite signals are obstructed
Solution Approach 1:
The patent introduces pseudolites as intermediary signal sources that transmit positioning signals locally within indoor or hidden environments. These pseudolites act as mediators between the user and the positioning system, enabling carrier phase measurements without requiring external satellite signals. The pseudolites are positioned at known locations and transmit signals that can be received by both reference stations and user terminals, solving the signal obstruction problem while maintaining positioning accuracy.
2Measurement precision
If carrier phase positioning method is used, then positioning accuracy of several mm to cm can be achieved, but geometry change is required for each measurement cycle which complicates the positioning process
Solution Approach 1:
The patent performs preliminary actions by pre-determining the positions of pseudolites and reference stations before actual positioning operations. The baseline between reference stations and the geometric relationships are established in advance, allowing the positioning system to proceed directly to carrier phase measurement without requiring real-time geometry changes. This preliminary setup simplifies the measurement cycle while maintaining the high accuracy benefits of carrier phase positioning.
3Measurement precision
If reference stations are fixed, then positioning can be performed, but the change in geometry does not occur which prevents accurate carrier phase positioning
Solution Approach 1:
The patent introduces dynamic elements by allowing at least one reference station to move between measurement points while maintaining its function as a reference. This movement creates the necessary geometry changes for carrier phase ambiguity resolution while the station continues to provide stable reference measurements. The dynamic reference station configuration enables the system to adapt to different positioning scenarios without sacrificing the stability required for accurate carrier phase measurements.
Data Source
AI summary
The locations of pseudolites and the location of a stationary reference station are previously known by a user processing unit, and codes and carrier phase of signals transmitted from the pseudolites are measured by the stationary reference station, a moving reference station and a rover receiver. Data of the codes and the carrier phase measured by the stationary reference station, the moving reference station and the rover receiver are transmitted to the user processing unit using a data link. The user processing unit determines a baseline between the stationary reference station and the moving reference station, and a baseline between the moving reference station and the rover receiver. The two baselines and the previously known location of the stationary reference station are employed to determine the position of the rover receiver.