Receiver Spur Suppression via Adaptive Notch Filtering
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Solution Overview
Problem
In wireless communication systems, spurs generated internally or externally interfere with the receiver's ability to properly demodulate signals, leading to poor sensitivity and performance in certain frequency channels.
Innovation Solution
A processor within the wireless device employs a notch filter with an adjustable notch frequency and bandwidth to detect and suppress spurs by performing a fast Fourier transform or discrete Fourier transform on digital samples, allowing for targeted filtering of undesired signals while minimizing the impact on the desired signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a receiver processes signals in certain frequency channels, then communication functionality is provided, but spurs generated internally cause poor sensitivity and performance
Solution Approach 1:
The patent converts the harmful spurs into a detectable pattern by accumulating multiple received signals. The spurs, being deterministic and repeating at the same frequency and phase, constructively interfere during accumulation, making them stand out as peaks in the spectral analysis. This allows the system to identify and subsequently suppress the spurs that would otherwise degrade receiver sensitivity.
Solution Approach 2:
The patent introduces an intermediary processing stage between signal reception and demodulation. This intermediary performs spectral analysis and spur detection, identifying problematic frequencies before they adversely affect demodulation. The system then applies selective filtering to remove identified spurs, acting as a mediator that protects the demodulation process from harmful interference.
2Object-generated harmful factors
If filtering is applied to remove spurs, then spur suppression is achieved, but part of the desired signal may be attenuated
Solution Approach 1:
The patent applies local quality by implementing selective filtering rather than broad-spectrum filtering. Instead of applying a uniform filter across the entire frequency band, the system performs spectral analysis to identify specific frequency locations where spurs occur, then applies filtering only at those localized frequency points. This preserves the integrity of the desired signal while removing only the harmful spur components.
Solution Approach 2:
The patent changes the parameters of the filtering operation based on detected spur characteristics. The filter's center frequency, bandwidth, and attenuation depth are adjusted according to the specific spur's frequency location and amplitude. This adaptive approach ensures effective spur suppression while minimizing impact on the desired signal, as the filter parameters are optimized for each specific spur rather than using fixed conservative settings.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves sensitivity and performance for affected frequency channels by effectively removing spurs, thereby enhancing communication quality without significantly attenuating the desired signal.
Implementation Method 1
The processor may detect for the spur, e.g., by performing a fast Fourier transform (FFT) or a discrete Fourier transform (DFT) on the digital samples and examining the resultant spectral response.
Implementation Method 2
The processor may filter the digital samples with a notch filter having an adjustable notch frequency and/or an adjustable notch bandwidth.
Data Source
AI summary
Techniques for suppressing spurs in a receiver are described. A processor (e.g., within a wireless device) receives digital samples for a desired signal having a spur located within the bandwidth of the desired signal. A spur is an undesired signal that may be generated internally at the receiver or may come from an external interfering source. The processor filters the digital samples to suppress the spur and provides output samples having the spur suppressed. The processor may detect for the spur, e.g., by performing an FFT on the digital samples and examining the spectral response. The processor may filter the digital samples with a notch filter having an adjustable notch frequency and/or an adjustable notch bandwidth. For example, the notch frequency may be set based on the frequency of the spur, and the notch bandwidth may be set based on the amplitude of the spur.