Playback Signal Detection Filters for Low-Latency Noise Control
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Solution Overview
Problem
Polymorphic playback systems in personal audio devices face challenges in detecting signal characteristics due to high latency introduced by strong low-pass filters needed to filter out-of-band noise, which affects in-band signal detection.
Innovation Solution
Implementing a polymorphic playback system with both lower-latency and higher-latency detection filters, where the lower-latency filter is used for detecting characteristics requiring quick response and the higher-latency filter for robust noise filtering, and a control subsystem manages the filter selection based on signal characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a strong low-pass filter is used to filter out-of-band noise, then noise filtering is improved, but latency in signal detection increases
Solution Approach 1:
The patent divides the single filter function into multiple parallel filters with different latency characteristics. Specifically, it uses a first low-pass filter with lower latency and a second low-pass filter with higher latency, allowing the system to segment the filtering task and select appropriate filters based on signal conditions.
Solution Approach 2:
The system dynamically switches between different filter configurations based on detected signal characteristics. When out-of-band noise is detected, the system selects the higher-latency second low-pass filter for robust noise filtering. When no significant noise is present, it uses the lower-latency first low-pass filter to minimize detection latency, making the filter selection adaptive to changing conditions.
2Object-affected harmful factors
If a strong low-pass filter is used to filter out-of-band noise, then noise filtering is improved, but signal quality for in-band signals deteriorates
Solution Approach 1:
The patent segments the filtering function into multiple parallel paths with different filtering strengths. The first low-pass filter provides lighter filtering with lower latency, while the second low-pass filter provides stronger filtering with higher latency. This segmentation allows the system to choose the appropriate filtering level based on actual noise conditions.
Solution Approach 2:
The system changes the filter parameters (cutoff frequency, filter order) based on detected signal characteristics. When out-of-band noise is detected above a threshold, the system switches to the second low-pass filter with more aggressive filtering parameters. When noise levels are acceptable, it uses the first low-pass filter with more conservative parameters that preserve in-band signal quality.
3Speed
If filter latency is reduced for quick signal detection, then response speed is improved, but noise filtering capability deteriorates
Solution Approach 1:
The system dynamically adapts its filtering strength based on detected noise levels. When the signal detector identifies out-of-band noise above a threshold, it switches to the higher-latency second low-pass filter for robust noise filtering. When noise levels are acceptable, it uses the lower-latency first low-pass filter to maintain fast response speed, making the filtering capability adaptive rather than static.
Solution Approach 2:
The patent creates a parallel copy of the filtering function with different characteristics. Instead of modifying a single filter, it implements a second low-pass filter as a copy with different parameters (higher latency, stronger filtering). This allows the system to switch between copies based on conditions without losing the original fast-response filter configuration.
Data Source
AI summary
A polymorphic playback system is disclosed in which one or more parameters of a signal path of the polymorphic playback system are varied based on one or more characteristics of a playback signal processed by the signal path, wherein the polymorphic playback system may include a lower-latency detection filter, a higher-latency detection filter, and a control subsystem that uses the lower-latency detection filter for detecting the one or more first characteristics of the playback signal and uses the higher-latency detection filter for detecting the one or more second characteristics of the playback signal.