Click Noise Detection and Phase Domain Correction in FM Receivers
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Solution Overview
Problem
Existing methods for reducing click noise in FM radio receivers are inadequate, as they either distort the desired signal or fail to effectively remove low-frequency audible clicks, leaving inaudible disturbances intact.
Innovation Solution
A method utilizing a first detector unit and a second correction unit, where the detector differentiates the input signal to extract noise samples, compares their sum with a threshold, and the correction unit corrects the signal in the phase domain before outputting it, specifically targeting and removing audible clicks with low-frequency content while leaving inaudible disturbances untouched.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If existing methods are used to reduce click noise, then click noise is reduced, but the desired signal is distorted or corrupted
Solution Approach 1:
The patent segments the signal processing into distinct functional blocks: a click detector that identifies click noise occurrences and a corrector that repairs only the detected click portions. This segmentation allows targeted noise removal without affecting the entire signal, thus preserving signal quality while reducing click noise.
Solution Approach 2:
The corrector applies correction only to the specific time regions where clicks are detected, rather than processing the entire signal uniformly. This local quality approach ensures that the desired signal portions remain undistorted while only the harmful click portions are corrected.
2Object-affected harmful factors
If existing methods are used to reduce click noise, then some noise is removed, but audible clicks with low-frequency content remain
Solution Approach 1:
The detector uses differentiated signal analysis and compares the sum of two noise samples against a threshold to identify clicks. This parameter-based detection method is specifically tuned to detect low-frequency audible clicks that were previously missed by existing methods, improving detection accuracy for the problematic click types.
3Object-affected harmful factors
If existing methods are used to reduce click noise, then processing is applied, but inaudible disturbances are not effectively removed
Solution Approach 1:
The patent converts the limitation of being selective (only removing audible clicks) into a benefit by preserving inaudible disturbances that contain useful signal information. The method recognizes that inaudible disturbances are less harmful than audible clicks, so it prioritizes removing only the harmful audible portions while leaving the less harmful inaudible portions intact.
Data Source
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AI summary
The invention relates to an apparatus and a method for detecting and correcting input signals regarding click noise, using a first detector unit (2,21) unit and a second correction unit (3,22), the detector unit (2,21) differentiates the input signal (4,23) and extracts the noise signal (6) and compares (8,33) the sum of two noise samples with a threshold value (35/T 2 ) and in case this sum exceeds the threshold value (35/T 2 ) a click is observed, while the correction unit (3,22) corrects (9) the input signal (4,23) in the phase domain and differentiates (11) it prior to outputting the corrected signal.