Active Noise Cancellation System

Project

Active noise cancellation systems are implemented in a wide range of applications. They are interesting examples of signal processing, and most users overlook the methods used to achieve such satisfying results.

Objectives

• Create an active noise cancellation system capable of 20 dB of noise cancellation
• Make the system modular in nature to be used in any sort of unidirectional enclosed environment
• Make a product that is capable of teaching others about noise cancellation in an intuitive manner
• Improve our abilities in signal processing and FPGA development

System

Figure 1. Photo of System with Block Diagram Overlay

Figure 2. Block Diagram of FPGA Module Connections

Methods

• Develop a system-level design of components and methods required to process audio signals and compute an anti-noise signal
• Develop a MATLAB model to focus on the filtering algorithm without analog signals creating additional variables
• Write HDL to implement the filtering algorithm from the MATLAB model
• Write HDL to interface with ADC/DAC peripheral boards using I2S2 communication protocol
• Simulate filter HDL and verify results with MATLAB model values
• Integrate HDL and hardware into a cohesive system
• Test the complete system, find bugs, and optimize the processing

Conclusion

• Continued testing needs to be done with more types of sound before it can be considered a viable product for consumers
• We learned to perform real time DSP on audio signals and had to consider factors we had not originally thought of or considered
• We would like to test with even higher input noise sources, use different filter algorithms, and develop a PCB to refine the hardware connections

Figure 3. Spectrogram of Multi-Frequency Noise Cancellation

Figure 4. Measured Attenuation of ANC System Versus Delay and Inverse