Satellite Signal Acquisition via Differential Code Correlation
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Solution Overview
Problem
Conventional GPS receiving devices face significant challenges in quickly acquiring satellite signals due to Doppler frequency shifts and clock errors, leading to lengthy frequency search processes.
Innovation Solution
A method that generates a differential code using segments of the satellite signal and correlates it with a replica code to acquire the satellite signal, eliminating the need for frequency search, thereby reducing acquisition time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency search is performed to account for Doppler frequency shifts and clock errors, then the satellite signal can be acquired with frequency accuracy, but the acquisition time becomes excessively long
Solution Approach 1:
The patent extracts and eliminates the frequency search process from the signal acquisition method. By using a fixed correlation frequency and differential code generation, the method removes the time-consuming frequency search step while still achieving accurate signal acquisition through code phase correlation alone.
Solution Approach 2:
The patent performs preliminary differential operation on the spreading code to generate a differential code before correlation. This preliminary processing eliminates the need for frequency search during the actual acquisition process, as the differential code inherently compensates for frequency variations caused by Doppler effects and clock errors.
2Measurement precision
If correlation calculation is performed in both frequency direction and code phase direction, then the satellite signal can be acquired with high precision, but the computational complexity and time consumption increase significantly
Solution Approach 1:
The patent extracts and removes the frequency direction correlation calculation from the acquisition process. By using differential code generation and fixed frequency correlation, it eliminates the complex two-dimensional search while maintaining code phase acquisition precision.
Solution Approach 2:
The patent replaces the mechanical frequency search process with a mathematical differential code generation approach. Instead of physically searching through frequency ranges, the method uses differential operations on the spreading code to compensate for frequency variations, significantly reducing computational complexity.
3Measurement precision
If the GPS receiving device minutely changes frequency to correlate received signal and replica signal, then frequency errors can be corrected, but the acquisition process becomes extremely time-consuming
Solution Approach 1:
The patent extracts and eliminates the iterative frequency adjustment process from the acquisition method. By using differential code generation with fixed frequency correlation, it removes the time-consuming loop of minutely changing frequency while still achieving frequency error correction through the differential code's inherent properties.
Solution Approach 2:
The patent performs preliminary differential operation on the spreading code to pre-compensate for frequency errors. This preliminary action eliminates the need for iterative frequency adjustment during acquisition, as the differential code already accounts for Doppler shifts and clock errors before the correlation process begins.
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 significantly reduces the time required to acquire a satellite signal, improving accuracy and efficiency by focusing only on code phase correlation, thus overcoming the limitations of traditional frequency search methods.
Implementation Method 1
obtaining a correlation value by performing a correlation using the differential code and a replica of the spreading code
Data Source
AI summary
Methods and apparatuses for acquiring a satellite signal includes generating a differential code using first, second and third segments of a satellite signal received from a positioning satellite, obtaining a correlation value by performing a correlation using the differential code and a replica of the spreading code, and acquiring the satellite signal using the correlation value. The differential code is generated by performing a differential operation on a spreading code from the positioning satellite.