Modified C/A Code Nulling for GNSS Interference Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
GNSS receivers face significant performance degradation due to electromagnetic interference (EMI) from various sources, which can lead to increased error rates or complete signal loss, affecting the accuracy and reliability of satellite navigation systems.
Innovation Solution
A system and method that includes a processor and correlator circuit to detect interference signals and generate a modified coarse/acquisition (C/A) code with null values for interfering frequencies, which is combined with the satellite navigational system signal to partially remove interference, thereby improving signal correlation and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional GNSS receivers process satellite signals without interference mitigation, then the receiver structure remains simple and processing is straightforward, but electromagnetic interference causes increased error rates and signal loss
Solution Approach 1:
The system performs preliminary detection of interference signals using a correlator circuit before main signal processing. When interference is detected, the processor modifies the C/A code in advance by setting null values at interfering frequencies, preventing interference from degrading signal quality during subsequent correlation operations.
Solution Approach 2:
The system dynamically changes parameters of the C/A code based on detected interference conditions. The processor modifies the code by setting specific frequency portions to null values, transforming the code from its standard form to a modified form that excludes interfering frequencies, thereby adapting the receiver to current interference conditions.
2Reliability
If the receiver continuously monitors and processes interference signals, then interference mitigation is improved, but power consumption increases
Solution Approach 1:
The system employs periodic correlation processing where the correlator circuit operates at specific intervals to detect interference signals. The processor only modifies the C/A code when interference is detected during these periodic checks, rather than continuously processing and modifying codes, thereby reducing overall power consumption while maintaining effective interference mitigation.
3Measurement precision
If the C/A code is modified to include null values for interference frequencies, then interference is reduced in the correlated signal, but the code structure becomes more complex
Solution Approach 1:
The system applies local modifications to the C/A code by setting null values only at specific frequency portions where interference is detected, rather than modifying the entire code structure. This localized approach preserves the integrity of the C/A code at non-interfering frequencies while eliminating interference at affected frequencies, achieving precise signal correlation without unnecessary code complexity.
Data Source
AI summary
According to one general aspect, an apparatus may include a receiver, a processor, and a correlator circuit. The receiver may be configured to receive a satellite navigational system signal. The processor may configured to, if an interference signal is detected: receive an indication of a detected interference signal, and generate a modified coarse/acquisition (C/A) code, wherein the modified coarse/acquisition (C/A) code includes a null value for at least one frequency portion associated with the interference signal. The correlator circuit may be configured to, if an interference signal is detected, generate a correlated signal in which the interference signal has been at least partially removed by combining the modified C/A code and the satellite navigational system signal.