PLL Interference Cancellation for Modulated Signal Jamming
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing technologies face challenges in effectively removing modulated interference from input signals, particularly those with known or suspected modulation frequencies, as they can be difficult to isolate due to their structured shape, which can lead to signal jamming.
Innovation Solution
A signal receiver system utilizing phase locked loop (PLL) filters to demodulate, estimate, and subtract modulated interference components from input signals by re-creating and removing them based on known or estimated modulation frequencies and center frequencies, with configurations for serial or parallel connection of PLL filters depending on interference overlap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If modulated interference components are removed using traditional spectral peak identification methods, then continuous-wave interference can be eliminated, but modulated interference with structured shapes cannot be effectively removed
Solution Approach 1:
The patent segments the interference removal process into multiple specialized PLL filters, each configured to target specific modulation types (e.g., FSK, MSK, CW). This segmentation allows the system to handle different interference types independently through parallel processing, resolving the contradiction between reliable removal of specific interference and adaptability to various interference forms.
Solution Approach 2:
The patent changes key parameters (modulation frequency, center frequency, peak magnitude, phase) of the PLL filters to adapt to different interference characteristics. By dynamically adjusting these parameters based on spectral analysis, the system achieves both reliable removal of target interference and adaptability to different interference types.
2Measurement precision
If PLL filters are used to demodulate and reconstruct modulated interference, then accurate interference removal is achieved, but system complexity increases
Solution Approach 1:
The patent implements a selective approach where PLL filters are deployed only for specific modulation types that are actually present in the interference environment. Rather than implementing all possible modulation type handlers, the system uses spectral analysis to identify which filters are needed, reducing overall complexity while maintaining high precision for target interference removal.
Solution Approach 2:
The patent designs the PLL filter architecture with universal components that can be configured for different modulation types through parameter adjustment rather than requiring completely separate processing chains. The shared spectral analysis and signal reconstruction pathways provide multi-functionality, reducing device complexity while maintaining measurement precision.
3Productivity
If multiple PLL filters are connected in parallel to handle non-overlapping interference, then processing efficiency improves, but coordination between filters becomes more complex
Solution Approach 1:
The patent segments the frequency spectrum into distinct non-overlapping bands, with each PLL filter dedicated to a specific band. This segmentation eliminates the need for complex coordination between filters, as each operates independently on its assigned frequency range, maintaining both high productivity and manageable complexity.
4Measurement precision
If spectral analysis is performed to estimate center frequency, then accurate interference identification is achieved, but processing time increases
Solution Approach 1:
The patent performs preliminary spectral analysis to identify the presence and characteristics of modulated interference before engaging the full PLL filtering process. This preliminary action allows the system to quickly estimate center frequencies and modulation types, reducing the time required for subsequent interference removal while maintaining accurate measurement.
Data Source
AI summary
A system and method for removing modulated interference (e.g., FSK, MSK, CW) from an input signal demodulates the input signal into a tracking bitstream via a set of phase locked loop (PLL) filters, one PLL filter for each modulated interference component (e.g., signal) known or suspected to be interfering with the input signal. Each PLL filter estimates, based on an estimated modulation frequency and center frequency associated with its target modulated interference component, a peak magnitude, phase, and updated center frequency and, based on these parameters, approximates the target interference component. Each re-created modulated interference component is subtracted from the original input signal to produce an output signal from which the known or suspected modulated interference components have been substantially removed.