Adaptive Filter Taps and Gain for Interference Suppression
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Solution Overview
Problem
Modern communication systems face challenges in effectively handling narrowband interference due to intentional or unintentional jamming and multipath distortion, especially in wideband radio channels, which can cause bit errors and disrupt signal reception.
Innovation Solution
An adaptive filter system with variable delay and tap selection, using feedback from demodulator state and output power to automatically adjust gain and tap order, allowing for real-time interference suppression and multipath resolution, suitable for wideband waveforms in tactical radio environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If adaptive filters with more filter taps are used to handle multiple interferers, then interference suppression capability is improved, but device complexity and platform resource consumption increase
Solution Approach 1:
The patent implements dynamic adaptation of filter parameters including variable update gain that adjusts based on signal conditions, and configurable number of filter taps that can be optimized for different interference scenarios. This allows the filter to adapt its complexity dynamically rather than being fixed, resolving the contradiction between handling multiple interferers and maintaining platform constraints
Solution Approach 2:
The system changes key parameters such as update gain and filter tap configuration based on operating conditions and interference characteristics. By adjusting these parameters dynamically, the system can effectively suppress multiple narrowband interferers while adapting the filter complexity to match the actual interference environment and platform capabilities
2Speed
If faster adaptation speed is used in adaptive filters, then real-time interference suppression is improved, but noise enhancement and signal distortion increase
Solution Approach 1:
The update gain is implemented as a dynamic parameter that can be adjusted based on signal conditions and adaptation progress. During initial adaptation, higher update gain provides faster tracking of interferers, while during steady-state operation, the update gain can be reduced to minimize noise enhancement and maintain signal quality, thus resolving the contradiction between adaptation speed and signal integrity
Solution Approach 2:
The adaptive filter operates in different phases with different update gains - an initial acquisition phase with higher update gain for fast adaptation, followed by a tracking phase with lower update gain for stable operation. This periodic switching between adaptation modes allows the system to achieve both fast initial response and sustained signal quality
Data Source
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AI summary
A communications system receives a modulated signal that carries encoded communications data. An adaptive filter has a plurality of non-adaptive and adaptive filter taps with weighted coefficients and an adaptive gain circuit for updating the adaptive gain of the adaptive filter responsive to a received state of a modem or the type of modulation used by communications system. A demodulator and decoder receive the filtered output signal from the adaptive filter and demodulate and decode the signal to obtain the communications data.