GNSS Relative Positioning via Time Domain Recursive Filtering
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Solution Overview
Problem
Single-frequency GNSS receivers face accuracy issues due to ambiguity in carrier phase measurements, which are not compensated for, unlike dual-frequency receivers, affecting relative positioning accuracy, especially in urban environments with multipath signal interference.
Innovation Solution
The implementation of time domain recursive filtering techniques using data from multiple GNSS receivers to improve position accuracy by averaging double difference float ambiguities over time, allowing for more robust position estimation and reducing the impact of multipath biases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single-frequency GNSS receivers use carrier phase measurements for positioning, then positioning capability is provided, but accuracy deteriorates due to uncompensated ambiguity
Solution Approach 1:
The patent introduces an intermediary filtering process that processes carrier phase measurements from multiple single-frequency receivers to eliminate ambiguities. The filter acts as a mediator between the raw measurements and the final position estimate, resolving the contradiction by allowing carrier phase usage while removing its harmful ambiguity effect through multi-receiver temporal filtering.
Solution Approach 2:
The patent combines measurements from multiple single-frequency receivers to achieve dual-frequency-like accuracy. By merging data from multiple receivers and applying temporal filtering, the system achieves ambiguity resolution that would normally require dual-frequency hardware, thus improving accuracy without changing the receiver frequency capability.
2Measurement precision
If dual-frequency receivers are used to compensate for carrier phase ambiguity, then positioning accuracy is improved, but device cost and complexity increase
Solution Approach 1:
The patent creates a virtual dual-frequency effect by copying and processing measurements from multiple single-frequency receivers. Instead of using actual dual-frequency hardware, the system replicates the measurement process across multiple receivers and uses temporal filtering to synthesize the ambiguity-resolution capability of dual-frequency receivers, thereby achieving the same accuracy with simpler, cheaper hardware.
Solution Approach 2:
The patent makes single-frequency receivers universal by enabling them to achieve dual-frequency level accuracy through the filtering method. The same single-frequency receiver can be used for both standard positioning and high-accuracy relative positioning applications, eliminating the need for specialized dual-frequency hardware in specific use cases.
3Measurement precision
If carrier phase measurements are used in urban environments, then positioning is provided, but accuracy deteriorates due to multipath signal interference
Solution Approach 1:
The patent converts the harmful multipath effect into a beneficial filtering opportunity. By collecting measurements over time from multiple receivers, the system allows multipath-induced variations to manifest and then uses temporal filtering to distinguish them from true position changes, effectively converting the harmful interference into data that can be filtered out to reveal the true signal.
Data Source
AI summary
In general, the disclosure describes techniques for estimating a relative position of a receiver in a global navigation satellite system (GNSS) using time domain recursive filtering applied to GNSS data for an additional plurality of receivers. For example, multiple receivers each obtains GNSS data that indicates the raw position information for the receiver. A system applying techniques described herein may use the GNSS data, obtained for each receiver of the additional plurality of receivers, to improve position accuracy for a particular receiver using time domain recursive filtering.