Code Phase Search Peak Selection for GPS Acquisition
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Solution Overview
Problem
The GPS system faces a long initial signal acquisition phase, requiring a significant amount of time to search for and align with satellite signals, which limits the response time in emergency communication scenarios.
Innovation Solution
A method for code phase processing in wireless communication devices that involves correlating received pseudo noise spread signals with multiple code phases and frequency hypotheses, identifying a maximum peak and a second peak, and using cross-correlation to discard potential cross-correlation results, allowing for faster position fix acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a traditional sequential search method is used to acquire GPS satellite signals, then the search process is simple to implement, but the acquisition time is excessively long (5 to 10 minutes)
Solution Approach 1:
The patent applies preliminary action by performing cross-correlation processing between maximum peaks of different pseudo-random codes before final signal acquisition. This preliminary check identifies and eliminates potential cross-correlation false peaks in advance, allowing the receiver to skip unnecessary sequential searching steps and directly acquire valid satellite signals, thereby reducing acquisition time from 5-10 minutes to much faster rates
Solution Approach 2:
The patent uses copying by generating multiple pseudo-random code sequences (different PRN codes) and their corresponding maximum peaks in parallel. Instead of sequentially testing each code phase hypothesis, the system creates copies of the correlation processing for multiple codes simultaneously, enabling parallel evaluation and dramatically reducing the time required to identify valid satellite signals among potential false peaks
2Measurement precision
If multiple pseudo-random codes are searched to identify valid satellite signals, then position accuracy is improved, but processing complexity and time consumption increase significantly
Solution Approach 1:
The patent applies the taking out principle by extracting and isolating the maximum peak information from each pseudo-random code correlation result. Instead of processing entire correlation functions or searching through all code phases sequentially, the system extracts only the maximum peak parameters (amplitude, phase, frequency) from each code, simplifies the comparison process to operate on these extracted features rather than full correlation data, thereby reducing processing complexity while maintaining position determination accuracy
Solution Approach 2:
The patent changes parameters by transforming the correlation results from full correlation functions into simplified peak parameters (amplitude, phase offset, frequency). This parameter transformation reduces the data volume and complexity of subsequent cross-correlation comparisons between different PRN codes, enabling faster processing while preserving the essential information needed for accurate position determination
3Measurement precision
If cross-correlation processing is performed to eliminate false peaks, then position determination accuracy is improved, but processing time and computational load increase
Solution Approach 1:
The patent applies partial action by performing cross-correlation processing only on the extracted maximum peak parameters rather than on complete correlation functions or all possible code phases. This partial processing approach focuses computational resources only on the most critical peak identification step, achieving sufficient accuracy for position determination without the excessive time and computational load of exhaustive cross-correlation searches across entire signal waveforms
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 reduces the time required for GPS satellite signal acquisition and enables quicker position determination by conserving processing and power within the device, facilitating faster initial position fixes even with limited satellite visibility.
Implementation Method 1
A correlator correlates the received signal to a plurality of code phases in each of a plurality of frequency hypothesis
Data Source
AI summary
Methods and apparatus for code phase processing in a wireless communication device are described herein. A wireless device performs code phase search on a pseudo random code spread signal received over a wireless channel. A correlator correlates the received signal to a plurality of code phases in each of a plurality of frequency hypothesis. A maximum peak and a second peak are determined from the correlation results. Cross correlation processing is performed on the maximum peak and the maximum peak is discarded in favor of the second peak for position processing based on the results of the cross correlation.