Active Sonar Noise Elimination Using Multi-Constant Integration
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Solution Overview
Problem
Existing active sonar technologies face challenges in accurately detecting target objects due to noise with multiple frequency components, as current methods struggle to sufficiently suppress noise, particularly when the integration time constant does not match the noise frequency.
Innovation Solution
The active sonar apparatus employs a noise elimination unit with multiple integration devices having different integration time constants, which integrate and combine normalized signals to suppress noise effectively, emphasizing signals from target objects by distinguishing between noise and object reflections based on duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time integration is performed for each frequency using FFT process, then noise suppression is achieved, but when integration time constant is fixed, noise with multiple frequency components cannot be sufficiently suppressed
Solution Approach 1:
The patent segments the noise suppression process by dividing the frequency spectrum into multiple frequency bands and applying different integration time constants to each band. This segmentation allows the system to handle different frequency components of noise with appropriately tailored integration parameters, resolving the contradiction between fixed integration time and multi-frequency noise suppression.
Solution Approach 2:
The patent implements dynamic adaptation by automatically adjusting the integration time constant based on the detected noise frequency characteristics. The system dynamically selects or adjusts integration parameters according to the actual noise conditions, transforming a fixed integration time constant into a variable parameter that adapts to different noise frequencies, thereby achieving effective noise suppression across multiple frequency components.
2Measurement precision
If normalization is performed to eliminate noise, then detection accuracy improves, but noise with varying frequencies remains difficult to suppress sufficiently
Solution Approach 1:
The patent applies local quality by performing normalization and noise suppression operations locally within each frequency band rather than uniformly across the entire spectrum. By calculating local average values and applying normalization specific to each frequency region, the system achieves effective noise elimination while preserving target signals, addressing the limitation of uniform normalization against multi-frequency noise.
Data Source
AI summary
An active sonar apparatus which emits a sound wave and detects a target object based on a sound reflected by this target object including an FFT part which performs the fast Fourier transform of the received sound wave to derive a frequency spectrum and outputs this as an FFT signal, a normalization part which normalizes the FFT signal and outputs this signal as a normalized signal, and a noise elimination unit which performs a plurality of smoothing processes to the normalized signal, combines the signals to which the smoothing processes are performed to generate a combined signal, and outputs the combined signal in which a noise received together with the reflected sound is suppressed.