GPS Speed Calculation Correction for Indirect Waves
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Solution Overview
Problem
Existing GPS systems inaccurately calculate movement speed due to errors in reception frequency analysis, leading to incorrect movement distance calculations.
Innovation Solution
A method to determine whether the reception signal is an indirect wave and apply a correction coefficient based on the relative speed between the transmission source and receiver, using the transmission and reception frequencies to accurately calculate movement speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If movement speed is calculated using reception frequency changes based on relative speed between GPS satellite and receiver, then movement speed can be obtained, but the calculated movement distance becomes shorter than the actual movement distance
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values for Doppler frequency offset based on receiver speed and satellite elevation angle before actual positioning. The correction table is prepared in advance, allowing the system to quickly retrieve and apply appropriate correction values during movement speed calculation without real-time computation delays
Solution Approach 2:
The patent changes parameters by introducing a correction value that adjusts the Doppler frequency offset based on varying parameters including receiver speed, satellite elevation angle, and signal characteristics. This parameter adjustment compensates for the systematic error causing underestimated movement distance, transforming the inaccurate speed measurement into an accurate one
2Loss of information
If Doppler frequency offset is used to calculate movement speed, then speed information can be obtained, but errors occur due to indirect wave reception and other factors
Solution Approach 1:
The patent implements feedback by using the calculated movement speed to determine the appropriate correction value from the correction table, then applying this correction to refine the movement speed calculation. This iterative feedback process continues until convergence, progressively eliminating errors caused by indirect wave reception and other factors
Solution Approach 2:
The patent introduces an intermediary correction mechanism that acts between the raw Doppler frequency offset measurement and the final movement speed calculation. The correction table serves as an intermediary data structure that translates measured frequency offsets into accurate speed values by compensating for systematic errors introduced by signal reflection and other interference
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
This approach allows for precise calculation of movement speed by correcting for errors associated with indirect wave reception, preventing erroneous speed calculations and improving accuracy.
Implementation Method 1
under the principle that the reception frequency changes depending on the relative speed of the GPS satellite and the GPS receiver, the movement speed of the GPS receiver can be calculated using the transmission frequency of the GPS satellite signal and the reception frequency in the GPS receiver
Data Source
AI summary
In a baseband processing circuit unit, a reception signal type determination unit determines whether or not a reception signal in a GPS reception unit is an indirect wave. A movement speed calculation unit calculates a movement speed of the GPS reception unit using a correction coefficient of a relative speed determined in accordance with the determination of whether or not the reception signal is an indirect wave, a transmission frequency of a GPS satellite signal and a reception frequency in the GPS reception unit.