Multi-path Interference Detection in GNSS Receivers
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Solution Overview
Problem
Global navigation satellite systems (GNSS) face accuracy issues due to multi-path interference, which distorts signals received by GNSS receivers through constructive and destructive interference with line of sight signals.
Innovation Solution
A method and apparatus for detecting multi-path interference in spread-spectrum signals by comparing variations of early and late correlation signals, generated with respective negative and positive phase offsets, to determine the presence and level of interference, using a processing unit within a spread-spectrum receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-path signals are received along with line of sight signals, then the GNSS receiver can maintain signal reception in complex environments, but the position calculation accuracy deteriorates due to constructive and destructive interference
Solution Approach 1:
The patent segments the correlation signal into multiple components by correlating with spreading codes at different offsets (early, prompt, late). This segmentation allows the receiver to separately analyze different signal components and identify multi-path interference patterns, thereby maintaining reliable signal reception while improving position calculation accuracy by distinguishing between direct and reflected signals.
Solution Approach 2:
The patent introduces an intermediary detection mechanism that monitors the relationship between early and late correlation signals. This intermediary system detects multi-path interference by analyzing power variations and relationships between different correlation components, serving as a mediator that identifies interference without disrupting the primary signal reception function.
2Productivity
If the GNSS receiver processes corrupted signals containing multi-path components, then continuous positioning can be maintained, but the measurement accuracy deteriorates
Solution Approach 1:
The patent performs preliminary detection of multi-path interference by analyzing the relationship between early and late correlation signals before final position calculation. This preliminary action identifies corrupted signal components, allowing the receiver to take corrective measures or flag affected measurements, thereby maintaining continuous positioning while improving accuracy by preventing corrupted data from degrading the solution.
3Reliability
If correlation signals with phase offsets are used for tracking, then signal tracking capability is maintained, but multi-path interference detection becomes necessary to preserve accuracy
Solution Approach 1:
The patent implements a multi-functional detection system that simultaneously performs tracking and multi-path interference detection using the same correlation infrastructure. The early and late correlation signals serve dual purposes: maintaining signal tracking through phase offset compensation and detecting multi-path interference through power relationship analysis. This universal approach maintains tracking capability while adding detection functionality without requiring completely separate systems.
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 identifies and quantifies multi-path interference, improving the accuracy of GNSS positioning by distinguishing signal variations caused by multi-path components from ideal conditions, thereby enhancing the reliability of satellite navigation systems.
Implementation Method 1
comparing a variation of a first signal corresponding to a correlation of the spread-spectrum signal and a spreading code having a first offset and a variation of a second signal corresponding to a correlation of the spread-spectrum signal and the spreading code having a second offset
Implementation Method 2
These multi-path signals may form constructive and destructive interference with corresponding LoS signals. The resultant signal processed by the GNSS receiver may be distorted by the multi-path components
Data Source
AI summary
A method for detecting multi-path interference in a spread-spectrum signal. A variation of a first signal and a variation of a second signal is compared. The variation of the first signal corresponds to a correlation of the spread-spectrum signal and a spreading code having a first offset. The variation of the second signal corresponds to a correlation of the spread-spectrum signal and the spreading code having a second offset. Multi-path interference is detected in dependence on the comparison.