GPS Semiconductor IC Doppler Candidate Positioning
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Solution Overview
Problem
Current GPS positioning methods, such as code phase and Doppler positioning, face challenges in maintaining accuracy when the elapsed time from previous positioning exceeds one hour, leading to waiting times and potential position jumps, especially at higher speeds.
Innovation Solution
A semiconductor IC and electronic device that utilize Doppler positioning to obtain a candidate position from multiple GPS satellites, calculating code phase differences and an index value to determine the reliability of this position, allowing for either code phase positioning using the candidate position or ZCount decoding to avoid waiting times and position jumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If code phase positioning is performed using the initial position from previous positioning when elapsed time exceeds one hour, then positioning speed is improved, but positioning accuracy deteriorates due to possible position differences greater than 150 km causing big jumps
Solution Approach 1:
The patent introduces Doppler positioning as an intermediary method to obtain a candidate initial position when elapsed time exceeds one hour. This candidate position serves as a mediator between the old initial position and the code phase positioning, avoiding direct use of potentially inaccurate previous positioning data while enabling faster positioning than waiting for ZCount decoding.
Solution Approach 2:
The patent performs Doppler positioning in advance to obtain a candidate initial position before executing code phase positioning. This preliminary action prepares a more reliable starting point for the subsequent code phase positioning process, reducing the risk of big jumps while maintaining speed.
2Measurement precision
If ZCount decoding is performed to obtain accurate initial position for code phase positioning, then positioning accuracy is improved, but positioning speed deteriorates due to approximately six seconds waiting time
Solution Approach 1:
The patent applies partial action by using Doppler positioning (which provides sufficient but not maximum accuracy) instead of full ZCount decoding. This partial approach achieves adequate positioning accuracy while significantly reducing the time required, avoiding the need for complete and time-consuming ZCount decoding in all cases.
Solution Approach 2:
The patent dynamically selects the positioning method based on elapsed time and conditions. When elapsed time is short, it uses previous positioning directly. When elapsed time exceeds one hour, it uses Doppler positioning to obtain a candidate initial position, thereby adapting the approach to current conditions to optimize both speed and accuracy.
3Productivity
If Doppler positioning is used to obtain candidate initial position, then positioning speed is improved by avoiding ZCount decoding wait time, but positioning accuracy deteriorates due to lower accuracy compared to code phase positioning
Solution Approach 1:
The patent merges Doppler positioning and code phase positioning into a two-stage process. Doppler positioning provides a candidate initial position quickly, and then code phase positioning refines this position for high accuracy. This combination leverages the speed advantage of Doppler positioning and the accuracy advantage of code phase positioning, achieving both fast and accurate positioning.
Solution Approach 2:
The patent performs Doppler positioning as a preliminary step to obtain a candidate initial position before executing code phase positioning. This preliminary Doppler positioning prepares a better starting point for the subsequent code phase positioning, enabling faster convergence to the accurate position without requiring full ZCount decoding.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate GPS positioning without waiting times by evaluating the reliability of the candidate position obtained through Doppler positioning, thereby reducing errors and maintaining positioning accuracy even at higher speeds.
Implementation Method 1
a first positioning portion that obtains, by Doppler positioning, a candidate position from a first radio wave received from a first satellite by the communication module, a second radio wave received from a second satellite by the communication module, a third radio wave received from a third satellite by the communication module, and a fourth radio wave received from a fourth satellite by the communication module
Data Source
AI summary
A first positioning portion, a calculator, and a second positioning portion are provided in an electronic device targeted for positioning. The first positioning portion obtains, by Doppler positioning, a candidate position which is a candidate for an initial position of the electronic device in code phase positioning from radio waves received from each of GPS satellites. The calculator calculates an index value indicating the magnitude of variation in code phase from a difference between a code phase obtained from the radio waves received from each of the GPS satellites and a code phase obtained based on a candidate position and a position of each GPS satellite. The second positioning portion performs the code phase positioning using ZCount or a candidate position according to the index value.