Waterproof Camera Microphone Noise Cancellation via Dual-Sensor Subtraction
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Solution Overview
Problem
Waterproof cameras face challenges in reducing vibrational noise picked up by microphones due to external and internal vibrations, which degrade the quality of the audio signal.
Innovation Solution
The implementation of a dual microphone system where a main microphone captures external audio and a reference microphone, isolated in an enclosed cavity, picks up vibrational noise, allowing for noise cancellation by subtracting the reference audio signal from the main audio signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective membrane is placed in front of the microphone to prevent water from entering the camera, then waterproofing is improved, but the membrane vibrates when the camera moves or external forces are applied, causing acoustic noise to be picked up by the microphone
Solution Approach 1:
The audio system is segmented into two separate microphone channels: a main microphone that captures both external audio and vibrational noise, and a reference microphone that captures only vibrational noise. This segmentation allows the system to separately process and subtract the noise component from the audio signal, resolving the contradiction between maintaining waterproofing and reducing vibrational noise.
Solution Approach 2:
A reference microphone is introduced as an intermediary element that specifically captures the vibrational noise generated by the protective membrane and internal components. This intermediary device enables the system to identify and isolate the harmful noise component without affecting the primary audio capture function, allowing for effective noise cancellation while maintaining waterproofing.
2Object-affected harmful factors
If the camera uses a dual microphone system with a reference microphone in an enclosed cavity, then vibrational noise is reduced through noise cancellation, but the device complexity increases
Solution Approach 1:
The reference microphone serves multiple functions: it captures vibrational noise from the protective membrane, detects internal component vibrations, and provides a reference signal for noise cancellation processing. This multi-functionality reduces the need for additional specialized components, thereby limiting the increase in device complexity while achieving effective noise reduction.
Solution Approach 2:
The enclosed cavity housing the reference microphone is designed to passively isolate the reference microphone from external acoustic signals while allowing it to detect internal vibrations. This self-contained design eliminates the need for additional active isolation mechanisms or complex mounting structures, reducing overall system complexity while maintaining effective noise capture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces vibrational noise, improving the signal-to-noise ratio and maintaining the quality of the desired audio signal in waterproof cameras.
Implementation Method 1
When the camera moves or external forces are applied to the camera, the membrane may vibrate. The vibrations may be picked up as acoustic noise by the microphone. Additionally, other vibrating components inside the camera may generate additional noise that may reach the microphone.
Implementation Method 2
The unwanted noise can then be removed by subtracting the second audio signal from the second microphone from the main audio signal from the main microphone.
Data Source
AI summary
A camera includes one or more microphone pairs. A first microphone (e.g., a main microphone) is ported to the outside of the camera and captures the desired external audio signal, but may also capture undesired vibrational noise. A second microphone has a similar structure to the first microphone, but is not ported to the outside of the camera. Instead, the second microphone is ported into an enclosed cavity (e.g., 1-2 cubic centimeters in volume). The second microphone may pick up the same vibration excitation and internal acoustic noise as the first microphone but very little of the desired external acoustic sounds around the camera. The unwanted noise can then be removed by subtracting the second audio signal from the second microphone from the main audio signal from the main microphone.