M-Code Phase Compensation for Dual Sideband Distortion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The M-code signal for GPS systems experiences phase distortion due to non-linear phase characteristics in the down-conversion process, leading to correlation loss and distortion in the double sideband correlation function, which affects the accuracy of signal acquisition and position generation.
Innovation Solution
A method involving complex rotation of the BOCI/BOCQ correlator output is applied to correct for the non-linear phase response, using replica signals with a 90-degree phase offset to compensate for the phase difference between the upper and lower sidebands, thereby restoring symmetry in the double sideband correlation curve and improving signal processing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct acquisition of M-code navigation signal with large correlator circuits is used, then processing gain is obtained, but phase distortion and correlation loss occur
Solution Approach 1:
The patent segments the correlation process into separate upper and lower sideband correlations, then combines them with appropriate phase weighting. This segmentation allows independent phase compensation for each sideband, resolving the correlation distortion caused by non-linear phase response while maintaining processing gain from the full correlator.
Solution Approach 2:
The patent applies phase compensation by adjusting the phase parameters of the upper and lower sidebands differently based on their respective non-linear phase responses. This parameter change compensates for the distortion and restores accurate correlation measurement.
2Measurement precision
If non-linear phase response correction is applied, then correlation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements phase compensation using feedback from measured or predetermined non-linear phase characteristics. The system measures or knows the phase response of the signal path and uses this information to apply corrective phase shifts, creating a closed-loop correction that improves accuracy without requiring complex real-time optimization.
Solution Approach 2:
The patent performs phase compensation in advance by applying predetermined phase corrections based on known non-linear phase characteristics of the signal path. This preliminary action eliminates the need for complex real-time phase optimization during signal acquisition, reducing processing complexity while maintaining accuracy.
Data Source
AI summary
A system and method of generating a position is disclosed. The system and method are configured for receiving from a transmitter an M-code signal, the M-code signal modulated with a pseudorandom number sequence. The system and method are also configured for down converting the received M-code signal to a baseband signal. Further, the system and method are configured for correlating the baseband signal with a known pseudorandom number sequence. Further still, the system and method are configured for processing the converted baseband signal to remove errors due to phase distortion of the M-code signal.