Positioning Apparatus Effective Range Correlation Filtering
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Solution Overview
Problem
Conventional positioning apparatuses struggle to accurately determine the current position in environments where the direct signals from satellites are weak, such as valleys or indoor locations with obstructions, leading to incorrect positioning due to maximized correlation values from multi-pass signals and noise.
Innovation Solution
The apparatus sets up effective ranges for correlation values based on pseudo distances between satellites and a reference station, detecting peak values within these ranges to distinguish direct satellite signals from multi-pass signals and noise, ensuring accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the prior art positioning apparatus determines position based on the largest correlation value, then positioning is simple and fast, but positioning accuracy deteriorates in environments with weak direct satellite signals due to multi-pass signals and noise
Solution Approach 1:
The invention changes the selection criterion from simply choosing the largest correlation value to selecting a correlation value whose peak position falls within an effective range determined by pseudo-distance. This parameter change in the selection logic allows the system to filter out multi-pass signals and noise while maintaining positioning speed.
Solution Approach 2:
The invention introduces an intermediary mechanism - the effective range determination based on pseudo-distance between satellites and reference station - that mediates between the raw correlation values and the final position determination. This intermediary layer filters out incorrect signals before position calculation.
2Adaptability or versatility
If the apparatus uses correlation calculation with pseudo pattern codes, then it can process satellite signals, but it cannot distinguish direct signals from multi-pass signals and noise in obstructed environments
Solution Approach 1:
The invention performs preliminary action by determining the effective range based on pseudo-distance before selecting the final correlation value. This preliminary step establishes a validation criterion that distinguishes direct signals from multi-pass signals and noise, enhancing signal discrimination accuracy while maintaining processing capability.
Data Source
AI summary
A positioning apparatus includes a correlator 30 for calculating a correlation between the pseudo pattern code of each of satellites 1 and 2 and each of SPS signals associated with the satellites 1 and 2, and for outputting a correlation value indicating the correlation, sets up effective ranges δ1 and δ2 for the correlation values outputted from the correlator 30 on the basis of a pseudo distance PR1 between the satellite 1 and a SPS reference station 4, and a pseudo distance PR2 between the satellite 2 and the SPS reference station 4, and detects peak values which fall within the effective ranges δ1 and δ2, respectively. As a result, the positioning apparatus can determine the current position correctly even under a receiving environment in which the electric waves directly from the satellites 1 and 2 may become weak.