Periodic Noise Reduction via Time-Domain Correlation
Solution Overview
Problem
Existing noise reduction devices struggle to effectively suppress periodic noise signals, especially when the frequency change is relatively fast, as they rely on converting input signals into a specific frequency range, which is inadequate for fast-changing noise frequencies.
Innovation Solution
A noise reduction device and method that frames input signals, calculates correlation values with a reference signal, selects candidate positions for noise reduction, and processes these signals to generate output signals with reduced periodic noise, even for fast-frequency changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the input signal is converted into a signal within a frequency range to detect periodic noise, then periodic noise with slow frequency change can be reduced, but periodic noise with fast frequency change cannot be reduced
Solution Approach 1:
The patent changes the fundamental parameter of noise detection from frequency-domain analysis to time-domain correlation analysis. By calculating correlation values between frame signals and reference signals in the time domain, the system can track and reduce periodic noise regardless of how fast its frequency changes, overcoming the limitation of frequency-range conversion methods
Solution Approach 2:
The patent stores a reference signal in advance that contains the periodic noise characteristics. This reference signal is then used for correlation calculation with incoming frame signals, allowing the system to proactively identify and reduce periodic noise without needing to convert to frequency domain first
Data Source
AI summary
A frame generator 3 frames an input signal and generates a frame signal. A reference signal storage unit 7 stores therein a reference signal showing a periodic noise signal. A correlation value calculator 8 calculates a correlation value between the frame signal and the reference signal. A correlation candidate position decider 9 decides a plurality of correlation candidate positions serving as candidates for a signal portion of the reference signal correlated with the frame signal. A noise reduction processor 10 reduces a periodic noise signal, which is included in the frame signal, by using each signal portion of the plurality of correlation candidate positions, and generates a plurality of candidate output signals. An output signal decider 11 decides a candidate output signal, in which the periodic noise signal is reduced the most among the plurality of candidate output signals, and outputs the decided output signal.