Smartphone GNSS Positioning via Rate-of-Change Observation Preprocessing
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Solution Overview
Problem
Current smartphone GNSS positioning technologies suffer from low precision due to inconsistencies between pseudorange and carrier observation values, limiting their application in everyday life and navigation tasks.
Innovation Solution
A high-precision point positioning method is developed using original GNSS observation values from smartphones, involving data preprocessing, satellite observation value weighting based on elevation angles, and improved static Kalman filtering to generate accurate positioning results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional GNSS positioning methods are used in smartphones, then the positioning function is available, but the positioning precision is low due to inconsistencies between pseudorange and carrier observation values
Solution Approach 1:
The patent applies parameter changes by transforming the observation value processing approach from direct use to preprocessing through differencing operations. Specifically, it uses pseudorange-rate and carrier-rate observation values to eliminate clock bias parameters, changing the mathematical parameters from absolute measurements to rate-of-change measurements, thereby resolving the inconsistency issue and achieving sub-meter positioning precision
Solution Approach 2:
The patent extracts and removes the harmful clock bias parameters from the observation equations by using rate-of-change measurements. By taking the time derivative of the pseudorange and carrier phase equations, the clock bias terms are eliminated, leaving only the geometric range and ambiguity terms that can be reliably solved for positioning
2Measurement precision
If original GNSS observation values are used directly, then data processing is simple, but positioning precision is insufficient for high-precision applications
Solution Approach 1:
The patent applies preliminary action by pre-processing the GNSS observation values through differencing operations before positioning calculation. The pseudorange-rate and carrier-rate values are computed in advance from the raw observations, and clock bias elimination is performed beforehand, so that the main positioning algorithm receives pre-conditioned data that converges faster and achieves higher precision
3Measurement precision
If conventional positioning algorithms are used, then implementation is straightforward, but convergence speed is slow and precision is limited
Solution Approach 1:
The patent changes the parameters from absolute pseudorange and carrier phase measurements to their time derivatives (rates). This parameter transformation eliminates the need to solve for clock bias parameters and reduces the correlation between parameters, leading to faster convergence of the Kalman filter and higher positioning precision within the same time frame
Data Source
AI summary
The present invention discloses a high-precision point positioning method and device based on a smartphone. The method of the present invention, which belongs to the technical field of satellite positioning, improves the conventional PPP uncombined positioning model, and only uses original GNSS observation values received by a smartphone to carry out high-precision positioning without GNSS reference stations. The positioning method of the present invention comprises following steps: acquiring original observation values of the smartphone, such as GNSS pseudoranges and carrier phases; after preprocessing the data to decrease part of error influences, generating an uncombined model from the original observation values according to an improved precise point positioning method based on an estimation of double clock biases; determining each satellite observation value weight according to a satellite elevation angle; and carrying out filtering positioning by an improved Kalman filtering method to give a high-precision point positioning result.