Dual Frequency Receiver for Satellite Positioning
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Solution Overview
Problem
Current dual-frequency receivers for satellite-based positioning face significant errors due to multipath propagation, which affect pseudo-distance and carrier phase measurements, especially in complex environments, and existing methods only provide limited improvements.
Innovation Solution
A dual-frequency receiver design with a main and secondary channel for ionospheric propagation correction, utilizing interspectral correlation and feedback loops to identify and correct common errors across both frequency channels, allowing for improved pseudo-distance and phase measurements by recomposing a local code coherent with the propagation channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional code discriminators and processing procedures are used, then the impact of multipath effects on time measurement is reduced, but the domain of effectiveness is restricted and carrier phase errors are only slightly improved
Solution Approach 1:
The patent combines code phase measurement and carrier phase measurement into a unified dual-frequency processing system. By merging the discrimination of code phase and carrier phase through interspectral correlation, the system achieves improved measurement precision across both domains simultaneously, rather than treating them as separate processing streams with limited effectiveness in各自的 domains.
Solution Approach 2:
The dual-frequency receiver system performs multiple functions through a single integrated processing architecture: it measures pseudo-distance, measures carrier phase, corrects ionospheric propagation errors, and eliminates multipath effects. This multi-functional approach allows the system to operate effectively across diverse measurement domains and propagation conditions.
2Device complexity
If single-frequency measurement is used, then the system is simpler, but the integrity of measurements cannot be sufficiently verified
Solution Approach 1:
The patent introduces a secondary frequency channel as an intermediary for verifying measurement integrity. By comparing measurements from two different frequencies, the system can identify and correct errors, including multipath effects and ionospheric disturbances. The secondary channel acts as a mediator that enables cross-validation of the primary measurement channel's data.
Solution Approach 2:
The system changes the frequency parameter by operating on two different GPS frequencies simultaneously. This parameter change enables the receiver to distinguish between direct-path signals and multipath signals, as well as to correct ionospheric delays. The dual-frequency approach transforms a single-parameter system into a multi-parameter system, enhancing measurement reliability through comparative analysis.
3Measurement precision
If advanced multipath reduction schemes like Double-Delta or MEDLL are used, then pseudo-distance measurement precision is improved, but the schemes remain linked to specific propagation models and have limited general applicability
Solution Approach 1:
The patent segments the measurement process into distinct code phase discrimination and carrier phase discrimination components, processed through separate but coordinated channels. This segmentation allows each component to be optimized independently while maintaining overall system flexibility. The code discriminator and carrier phase discriminator operate with different optimization criteria, reducing dependency on any single propagation model.
Solution Approach 2:
The system employs dynamic feedback loops that continuously adjust the discrimination parameters based on real-time signal conditions. The code phase loop and carrier phase loop dynamically adapt their tracking parameters, allowing the system to respond to varying propagation conditions without being constrained by fixed propagation models. This dynamic adaptation enhances versatility across different environmental conditions.
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 effectively eliminates multipath errors, enhancing the integrity and accuracy of both pseudo-distance and carrier phase measurements, while maintaining signal-to-noise ratio without prior processing of the P code, and allows for real-time correction of ionospheric propagation delays.
Implementation Method 1
means of interspectral correlation of the signals of the main and secondary channels already correlated by the local code, after frequency compensation of the relative Doppler shifts of the said signals
Implementation Method 2
after frequency compensation of the relative Doppler shifts of the said signals
Implementation Method 3
a secondary channel for a calculation for correction of ionospheric propagation robust to differential phase errors linked to the local reception environment of the signals
Data Source
AI summary
Dual-frequency receiver for satellite-based positioning, comprising a main measurement channel and a secondary channel for a calculation for correction of ionospheric propagation robust to differential errors linked to the local reception environment of the signals. Each channel comprises a code generator, a carrier phase generator, integrators, phase and code discriminators, a code phase numerically-controlled oscillator, a carrier phase numerically-controlled oscillator, carrier phase loop matched filtering means, and code phase loop matched filtering means. The receiver further including:means for determining the respective phase errors in the main and secondary channels comprising means of interspectral correlation of the signals of the main and secondary channels already correlated by the local code, after frequency compensation of the relative Doppler shifts of the signals; andrespective feedback loops for the code and carrier phase errors in the main and secondary channels.