GPS Semiconductor IC Doppler Positioning Time Zone Display
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Solution Overview
Problem
Existing GPS positioning methods, such as code phase positioning, face challenges when the elapsed time from the previous positioning exceeds one hour, leading to potential position inaccuracies and resulting in a waiting time due to the need to decode ZCount broadcasts.
Innovation Solution
A semiconductor IC that calculates a position using Doppler positioning, specifies a time zone based on the calculated position, and displays time accordingly, thereby avoiding excessive quality and potential inaccuracies associated with code phase positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If code phase positioning is used to calculate pseudo distance, then positioning accuracy is improved, but waiting time occurs when elapsed time exceeds one hour due to ZCount decoding requirement
Solution Approach 1:
The system performs Doppler positioning in advance to obtain position information without requiring ZCount decoding. This preliminary position data is then used as the basis for calculating pseudo distance in code phase positioning, eliminating the waiting time while maintaining accuracy
Solution Approach 2:
Doppler positioning acts as an intermediary method that provides position information between the satellite and the code phase positioning system. It bridges the gap by providing position data that enables code phase positioning to proceed without the usual ZCount decoding wait time
2Productivity
If code phase positioning is used with initial position from previous positioning, then positioning speed is improved, but position accuracy deteriorates when elapsed time exceeds one hour due to potential 150 km position difference
Solution Approach 1:
The system performs Doppler positioning in advance to obtain updated position information that reflects current location. This preliminary position data replaces outdated previous positioning data, ensuring both speed and accuracy when calculating pseudo distance
Solution Approach 2:
The system changes the source of position parameter from static previous positioning data to dynamic Doppler positioning data. This parameter update ensures the position information remains current and accurate even when elapsed time exceeds one hour
3Loss of time
If Doppler positioning is used to calculate position, then waiting time is eliminated, but positioning accuracy is lower compared to code phase positioning
Solution Approach 1:
The system merges Doppler positioning and code phase positioning methods. Doppler positioning provides the position basis without waiting time, while code phase positioning refines the pseudo distance calculation. The combination achieves both speed and accuracy that neither method alone can provide
4Measurement precision
If code phase positioning is performed irrespective of whether Doppler positioning is sufficient, then positioning accuracy is maintained, but excessive quality is achieved which is not preferable
Solution Approach 1:
The system changes the decision parameter from always performing code phase positioning to conditionally performing it based on Doppler positioning sufficiency. This parameter change enables the system to avoid unnecessary processing while maintaining accuracy when needed
Solution Approach 2:
The system uses Doppler positioning results to self-evaluate whether code phase positioning is necessary. This self-service mechanism allows the system to automatically determine the appropriate positioning method based on current conditions, reducing unnecessary processing complexity
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
The proposed solution allows for immediate time display without waiting for ZCount decoding, maintains accuracy by verifying position accuracy against time zones, and avoids excessive quality by utilizing Doppler positioning for time zone specification.
Implementation Method 1
In Doppler positioning, the position of the electronic device is directly calculated from a difference between a frequency at the time of transmission of the radio wave transmitted by the GPS satellite and a frequency of the radio wave received by the electronic device targeted for positioning.
Data Source
AI summary
An electronic device equipped with a communication device which is a GPS communication module is provided with a calculator, a specifying portion, and a display controller. The calculator calculates a position by Doppler positioning. The specifying portion specifies a time zone based on the position calculated by the calculator. The display controller causes a display device to display the time according to the time zone specified by the specifying portion.