Adaptive Filter Tap Order Selection 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, where existing adaptive filters may be too complex or inefficient, particularly in resource-constrained tactical radio environments.
Innovation Solution
The implementation of an adaptive filter with a variable delay between fixed and adaptive taps, allowing automatic tap order selection and update gain adjustment based on demodulator state and output power, to enhance interference suppression and multipath resolution, while optimizing the number of taps for effective jammer handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If adaptive filters with more taps are used to handle multiple interferers, then interference suppression capability is improved, but device complexity and computational load increase
Solution Approach 1:
The patent implements dynamic adaptation of filter parameters including variable tap coefficients that adjust in real-time based on signal conditions, variable filter order selection that changes the number of active taps, and adaptive update gain adjustment. This allows the filter to optimize its complexity dynamically - using more taps when multiple interferers are present and fewer taps when interference is minimal, thus resolving the contradiction between interference suppression capability and computational complexity
Solution Approach 2:
The patent changes key parameters of the adaptive filter including the filter order (number of taps), update gain, and tap coefficients based on detected signal conditions. By monitoring the input signal characteristics and adjusting these parameters dynamically, the system achieves high interference suppression when needed while reducing computational load when interference levels are low, effectively resolving the technical contradiction
2Speed
If faster adaptation speed is used in adaptive filters, then responsiveness to changing interference is improved, but signal distortion and noise enhancement increase
Solution Approach 1:
The patent implements dynamic adjustment of the update gain parameter that controls the adaptation speed. The update gain is adjusted based on the current signal conditions, demodulator state, and detected interference levels. When interference is strong and changing rapidly, the update gain increases to provide faster adaptation. When the signal is stable or during critical demodulation phases, the update gain decreases to prevent signal distortion and noise enhancement, thus resolving the contradiction between adaptation speed and signal integrity
Solution Approach 2:
The patent incorporates feedback mechanisms where the demodulator state and output power information are fed back to control the adaptive filter's update gain and other parameters. This closed-loop control allows the system to monitor signal quality and adjust adaptation speed accordingly - reducing update rates when signal integrity is at risk and increasing them when rapid interference tracking is needed, effectively resolving the contradiction
3Measurement precision
If more filter taps are used to resolve multipath components, then multipath resolution is improved, but processing time and computational load increase
Solution Approach 1:
The patent implements variable filter order selection that dynamically adjusts the number of active taps based on the detected multipath structure. When complex multipath environments are detected, the filter order increases to provide sufficient resolution. When the channel is simple or during time-critical operations, the filter order reduces to minimize processing time. This dynamic adjustment resolves the contradiction between multipath resolution and processing time
Solution Approach 2:
The patent segments the filter processing into different stages or modes with different tap configurations. Different numbers of taps are activated based on the specific processing requirements - using more taps for detailed multipath analysis when needed and fewer taps for rapid processing when appropriate. This segmentation allows the system to optimize the trade-off between resolution and processing time for different operational scenarios
Data Source
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AI summary
A communications system receives a modulated signal that carries encoded communications data. An adaptive filter has an input, a plurality of non-adaptive and adaptive filter taps with weighted coefficients, and an output. The received signal is passed through the adaptive filter and around adaptive filter and a switch selects which signal to pass to demodulator based on measured output power of the adaptive filter and of the original received signal. A demodulator and decoder receive the filtered output signal and demodulate and decode the signal to obtain the communications data.