Mobile GNSS Antenna Phase Center Compensation for RTK/PPP Accuracy
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Solution Overview
Problem
Traditional GNSS positioning techniques, including RTK and PPP, fail to adequately account for phase center offset (PCO) and phase center variation (PCV) characteristics of mobile device antennas, leading to inaccuracies in positioning measurements, particularly in mobile devices like smartphones.
Innovation Solution
Compensate for PCO and PCV by determining a phase center profile of the antenna in a fixed-frame condition and incorporating attitude information into the profile during non-fixed frame conditions using sensor data from the device, aligning the device frame to an earth-centered, earth-fixed frame with a rotation matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional GNSS positioning techniques are used, then the positioning system is simple and easy to implement, but the positioning accuracy is insufficient due to unaccounted PCO and PCV errors
Solution Approach 1:
The patent performs preliminary characterization of the antenna's phase center properties by determining the phase center profile in a fixed-frame condition before actual positioning operations. This pre-characterization allows the system to account for PCO and PCV effects during dynamic positioning without requiring complex real-time measurements, thus improving accuracy while managing system complexity.
Solution Approach 2:
The patent introduces an intermediary transformation model that relates the antenna phase center in the device frame to the earth-centered frame using rotation matrices and the determined phase center profile. This intermediary model enables accurate positioning by bridging the coordinate systems while accounting for antenna characteristics, resolving the contradiction between simplicity and precision.
2Measurement precision
If antenna phase center compensation is implemented, then positioning accuracy is improved, but the computational complexity increases due to attitude information processing
Solution Approach 1:
The patent pre-determines the phase center profile in a fixed-frame condition, which simplifies subsequent computational requirements. During dynamic positioning, the system only needs to transform this pre-determined profile using attitude information, reducing computational complexity compared to performing complex measurements and calculations in real-time.
Solution Approach 2:
The patent dynamically adapts the phase center profile by transforming it according to the device's attitude orientation. This dynamic transformation approach allows the system to maintain high positioning accuracy across various orientations while using computationally efficient rotation matrix operations rather than complex real-time characterization.
3Reliability
If the antenna phase center profile is determined in a fixed-frame condition, then the characterization is accurate and stable, but the system cannot directly handle mobile device operations in non-fixed conditions
Solution Approach 1:
The patent transforms the static phase center profile determined in fixed conditions into a dynamic representation suitable for mobile operations. By applying rotation matrices that account for device attitude orientation, the system adapts the stable characterized profile to dynamic non-fixed conditions, maintaining both reliability and adaptability.
Solution Approach 2:
The patent uses attitude information as an intermediary that bridges the fixed-frame characterization and non-fixed-frame operation. This intermediary parameter allows the system to translate the stable phase center profile into accurate positioning for mobile devices in various orientations, resolving the contradiction between stability and adaptability.
Data Source
AI summary
Techniques for global navigation satellite system (GNSS)-based positioning of a mobile device based on antenna phase center compensation are disclosed. The techniques can include determining a phase center profile of a receiver antenna of the mobile device that is placed in a fixed-frame condition and executing an antenna phase center compensation procedure upon detecting placement of the mobile device in a non-fixed frame condition. The antenna phase center compensation procedure can include obtaining attitude information of the mobile device based at least in part on sensor data obtained from one or more sensors of the mobile device, and incorporating the attitude information of the mobile device into the phase center profile of the receiver antenna of the mobile device. A global navigation satellite system-based positioning operation may be executed that includes antenna phase center compensation based at least in part on incorporating the attitude information into the phase center profile.