Satellite Signal Correction for Urban Multipath Interference
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Solution Overview
Problem
In metropolitan areas with high traffic demand, the limited environments suitable for receiving GNSS satellite signals and the presence of multipath signals from surrounding structures complicate high-precision time synchronization and positioning, as conventional methods struggle to accurately distinguish between direct and reflected waves, especially in densely built environments.
Innovation Solution
A satellite signal reception apparatus that includes a satellite antenna, a unit for collecting orbital and spatial information, and a signal correction unit to determine whether a satellite is in a Line-of-Sight (LOS) or Non-Line-of-Sight (NLOS) state, allowing for correction of satellite signals received in an NLOS state, assuming they are reflected waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional signal reception methods are used in metropolitan areas, then the system can operate in dense urban environments, but the positioning precision and time measurement accuracy deteriorate due to multipath signals from surrounding structures
Solution Approach 1:
The invention segments the satellite signal into direct wave components and reflected wave components by analyzing waveform characteristics. The signal processing unit divides the received signal based on correlation waveform shapes, allowing separate handling of direct and reflected signals to eliminate multipath interference from positioning calculations
Solution Approach 2:
The invention uses excessive action by collecting signals from more satellites than the minimum required for positioning. By requiring signals from at least four satellites and preferring six or more, the system can selectively use only direct wave components for positioning, discarding reflected wave components that would degrade accuracy
2Measurement precision
If conventional signal reception methods are used in metropolitan areas, then the system can operate in dense urban environments, but the time synchronization accuracy deteriorates due to propagation delay variations from multipath signals
Solution Approach 1:
The invention segments the time measurement process by separately identifying direct wave arrival times and reflected wave arrival times through correlation analysis. This allows the system to use only direct wave timing information for time synchronization, eliminating propagation delay variations caused by reflected paths
Solution Approach 2:
The invention implements feedback by continuously monitoring correlation waveform characteristics and dynamically adjusting signal selection. The signal processing unit uses feedback from waveform analysis to identify and select direct wave components for time measurement, ensuring consistent accuracy despite changing multipath conditions
3Ease of operation
If signal strength-based direct wave identification is used, then simple identification is possible, but the method fails in environments where direct and reflected waves are mixed with similar strengths
Solution Approach 1:
The invention replaces simple signal strength comparison (mechanical/electrical measurement) with waveform shape analysis using correlation functions. By substituting the identification method from amplitude-based to shape-based analysis, the system can reliably distinguish direct and reflected waves even when their strengths are similar
Solution Approach 2:
The invention changes the identification parameter from signal strength (amplitude) to waveform shape characteristics. By analyzing the temporal shape of correlation waveforms rather than their amplitude, the system can accurately identify direct waves regardless of signal strength variations or mixing with reflected waves
4Reliability
If waveform-based reflected wave identification is used, then reflected waves arriving later than direct waves can be identified, but the method fails when only reflected waves are received without direct waves
Solution Approach 1:
The invention inverts the identification logic by looking for characteristics of direct waves (sharp correlation peaks) rather than relying on the absence of direct waves. This allows the system to identify direct waves even when they are weaker or obscured, and to detect when no direct wave is present by the absence of characteristic direct wave correlation patterns
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
Enables high-precision positioning and time measurement by accurately differentiating between direct and reflected waves and correcting satellite signals, thereby improving synchronization precision and reducing the impact of multipath signals.
Implementation Method 1
a satellite antenna 21 that receives the satellite signal
Implementation Method 2
Reflected waves and diffracted waves are phenomena that occur when radio waves arriving from a satellite enter an antenna after being reflected or diffracted by buildings or the ground in the periphery of the reception antenna
Data Source
AI summary
A navigation satellite signal reception apparatus includes a satellite antenna; a satellite orbital information collection unit that collects orbital information of a navigation satellite; a peripheral environment spatial information collection unit that collects spatial information for a peripheral environment of an installation position of the satellite antenna; a positional information collection unit that collects positional information for the installation position of the satellite antenna; and a signal correction unit that performs a determination process to determine whether a navigation satellite associated with the received satellite signal is in a directly viewable state or in a non-directly-viewable state from the installation position of the satellite antenna, and that performs a correction process on a satellite signal from a navigation satellite in an NLOS state, on the assumption that the satellite signal is a reflected wave.