Signal Processing Device Noise Cancellation Clock Synchronization
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Solution Overview
Problem
Signal processing devices face increased processing loads and system restarts due to the need to change filter coefficients when handling digital audio signals with different sampling frequencies, making it difficult to maintain efficient operations across various sampling frequencies.
Innovation Solution
A signal processing device that includes a noise cancellation process clock generation unit, a noise canceling unit, and a sampling rate conversion unit to convert input digital audio signals to a fixed sampling frequency, allowing for noise cancellation without changing internal coefficients, thereby reducing processing loads and eliminating the need for system restarts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If filter coefficients are changed for each sampling frequency to process audio signals, then processing accuracy is improved, but processing load increases and system restarts are required
Solution Approach 1:
The patent changes the fundamental parameter of the noise cancellation system from variable filter coefficients adapted to each sampling frequency to a fixed-frequency noise cancellation process clock. This allows the system to maintain processing accuracy while eliminating the need to change coefficients, thereby reducing processing load and avoiding system restarts.
Solution Approach 2:
The noise cancellation process clock serves as a universal reference for all sampling frequencies (32kHz, 44.1kHz, 48kHz, 96kHz, etc.). The sampling rate conversion unit converts any input sampling frequency to the fixed noise cancellation process clock frequency, making the noise cancellation filter coefficients universal across all input frequencies without requiring changes or restarts.
2Reliability
If filter coefficients are changed for each sampling frequency, then noise cancellation performance is improved, but system continuity deteriorates due to required restarts
Solution Approach 1:
The system performs preliminary sampling rate conversion to convert any input audio signal to the fixed noise cancellation process clock frequency before noise cancellation processing. This preliminary action ensures that the noise cancellation filter always operates at a consistent frequency, maintaining performance while eliminating the need for system restarts when sampling frequencies change.
3Measurement precision
If the system operates in synchrony with the audio signal clock, then timing accuracy is improved, but adaptability to different sampling frequencies deteriorates
Solution Approach 1:
The noise cancellation process clock acts as an intermediary between the variable-frequency audio signal and the noise cancellation filter. The sampling rate conversion unit uses this fixed-frequency clock as a mediator to convert any input sampling frequency to the standard frequency, maintaining timing accuracy for noise cancellation while providing universal adaptability to all input sampling frequencies.
Data Source
AI summary
There is provided a signal processing device s including a noise cancellation process clock generation unit configured to generate a noise cancellation process clock having a predetermined fixed frequency, a noise canceling unit configured to include a noise canceling filter operating based on the noise cancellation process clock and generating a noise canceling signal having a signal property of canceling an external noise component based on an input audio signal including the external noise component picked up by a microphone, and an addition unit superimposing the noise canceling signal generated by the filter on a digital audio signal, and a sampling rate conversion unit configured to rate-convert the input digital audio signal sampled at a clock in asynchrony with the noise cancellation process clock to a signal at a sampling frequency in synchrony with the noise cancellation process clock and to supply the rate-converted signal to the addition unit.