RF Receiver Impulse Noise Filtering Under Out-of-Band Interference
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Solution Overview
Problem
Existing impulse noise mitigation techniques in wireless communication receivers are ineffective in detecting impulse noise under high carrier-to-interference ratios in the time domain and out-of-band interferers in the frequency domain, leading to unreliable noise detection and mitigation.
Innovation Solution
The implementation of two complex high pass filters that selectively admit frequency components above and below the desired signal bandwidth, with a state machine determining which filter to use based on mean magnitude measurements over a time interval T to optimize noise mitigation and reduce energy from other interferers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional impulse noise mitigation techniques are used in time domain, then impulse noise detection is simple, but detection reliability deteriorates under high carrier-to-interference ratios
Solution Approach 1:
The patent divides the frequency spectrum into multiple bands using separate band-pass filters, allowing independent analysis of different frequency regions. This segmentation enables reliable impulse noise detection in specific bands even when overall carrier-to-interference ratio is high, as the noise may be concentrated in particular frequency regions.
Solution Approach 2:
The patent transitions from time-domain analysis to frequency-domain analysis by applying FFT transforms and examining spectral characteristics. This dimensional change from time to frequency domain enables differentiation between impulse noise and carrier signals based on spectral properties, improving detection reliability under high carrier-to-interference conditions.
2Measurement precision
If frequency domain analysis is used to detect out-of-band interferers, then detection accuracy improves, but power consumption increases due to continuous filter operation
Solution Approach 1:
The patent implements dynamic filter selection based on detected interferer locations. The system continuously monitors the spectrum, identifies out-of-band interferers, and activates only the specific band-pass filters needed for current conditions. This dynamic adaptation maintains high detection accuracy while minimizing power consumption by keeping unnecessary filters inactive.
Solution Approach 2:
The patent applies different processing qualities to different frequency bands based on local interference conditions. Bands containing out-of-band interferers receive enhanced analysis with active filtering, while clean bands use minimal processing. This localized quality adjustment optimizes the balance between detection accuracy and power consumption.
3Reliability
If multiple band-pass filters are used to address out-of-band interference, then noise mitigation performance improves, but device complexity increases
Solution Approach 1:
The patent segments the frequency spectrum into multiple bands using parallel band-pass filters, each targeting specific frequency regions where out-of-band interferers may occur. This segmentation allows simultaneous mitigation of multiple interference sources while maintaining a modular architecture that manages complexity through organized frequency division.
Solution Approach 2:
The patent designs the band-pass filter bank to serve multiple functions: filtering out-of-band interferers, enabling frequency-domain analysis, and supporting adaptive selection based on detected conditions. This multi-functionality reduces overall system complexity by having a single filter bank structure accomplish multiple noise mitigation tasks.
Data Source
AI summary
A noise abatement method and system for impulse noise in an RF receiver where the RF analog signal is converted to a digital signal prior to being connected to a demodulator. Two filters are used to detect impulse noise signals even under out-of-band interferer conditions, and prevent the impulse noise from reaching the input to the demodulator. A first of the two filters detects impulse noise using signals lower than the frequency bandwidth of the desired signal, and a second of the two filters detects impulse noise using signals higher the frequency bandwidth of the desired signal. A mean magnitude of the signal is detected over a predetermined time T and is used to select which filter to use for noise abatement.