Satellite Navigation Interference Detection via Time Correlation
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Solution Overview
Problem
Existing satellite radio-navigation signal receivers face measurement errors and positioning inaccuracies due to interference from narrow-band signals, with existing detection methods being slow to detect interference.
Innovation Solution
A method that calculates cross-correlation between shifted correlation measurements to identify interference, using a device with additional correlations performed beyond the duration of a slot of the spreading code, and normalizes the intercorrelation by autocorrelation energies to set a stable interference indicator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional interference detection methods based on aberrant measurement detection are used, then interference can be detected, but the detection time is too long between interference appearance and actual detection
Solution Approach 1:
The patent performs correlation measurements at multiple time positions (ahead, at, and behind the maximum correlation point) in advance. By pre-calculating correlations at these shifted positions and storing them, the system is prepared to quickly compute the time correlation coefficient when interference detection is needed, eliminating the need for lengthy real-time analysis
Solution Approach 2:
The patent replaces traditional mechanical/time-consuming measurement analysis with a mathematical approach using time correlation coefficient calculation. Instead of analyzing measurement sequences over time, the system uses cross-correlation between shifted correlation measurements to rapidly identify interference through coefficient comparison against thresholds
2Device complexity
If correlation measurements are performed only at the maximum correlation position, then processing is simple, but interference detection capability is insufficient
Solution Approach 1:
The patent segments the correlation measurement process by performing measurements at multiple distinct time positions (ahead of maximum, at maximum, and behind maximum). This segmentation allows the system to capture different aspects of the signal and use their relationships (time correlation coefficient) to detect interference, improving reliability without excessive complexity
Solution Approach 2:
The patent introduces the time correlation coefficient as an intermediary metric that relates correlation measurements taken at different time positions. This coefficient serves as a mediator that captures the relationship between shifted measurements and enables interference detection through threshold comparison, balancing complexity and detection capability
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 method allows for rapid detection of interference, reducing positioning errors by comparing the normalized intercorrelation indicator with a power ratio-based threshold, effectively distinguishing between signal synchronization and interference presence.
Implementation Method 1
a correlator 103 to perform a correlation of the signal S with a spreading code generated locally 104
Data Source
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AI summary
A method for detecting interference in a satellite radio-navigation signal characterized in that it comprises the following steps: • Determining (201) the time position for which the correlation between said signal and a local spreading code offset by said position is maximum, • Calculating (202) information representative of the cross-correlation between at least a first measurement of the correlation of said signal with a local spreading code at a first time position ahead of the time position of said maximum by a duration greater than the duration of a spread code window and a second measurement of the correlation of said signal with a local spreading code at a second time position behind the time position of said maximum by a duration greater than the duration of a spread code window,• Compare (203) said information to a detection threshold configured at least according to the ratio of signal and interference powers.