The Design And Implementation Of An In-Vehicle Low Frequency Noise Active Cancellation System Based On Most Technology

Quietness is one of the most important criteria of car comfort,but the classic passive noise cancelling technology,such as damping materials,cannot significantly cancel the low-frequency noise due to the limitation of volume,so the Active Noise Cancellation(ANC)technology,which doesn't restrain the vehicle structure,material and so on,has received more and more attention.To optimize the ANC system design and noise cancelling result,distinguishing from classic ANC system for entire vehicle,based on the integration of MOST(Media Oriented System Transport)Technology and classic ANC technology,a local ANC system which consists of multiple DSPs,digital microphones and amplifiers was designed and implemented,and its cancelling ability on low-frequency noise control was proved in the lab.This article mainly completed the following work:Firstly,the current status and development of ANC technology were deeply studied,and the main issues of current in-vehicle ANC system were analyzed,and as a replacement of global noise cancelling,a local noise cancelling method was proposed,so the research object was narrowed to passenger head zone from entire car.Secondly,based on simulation and experiments,on one hand,a noise signal processing application was accomplished.This application is based on the basic tools of digital signal processing like Finite Impulse Response low-pass filter and Power Spectrum Density Analysis.On the other hand,based on the cancelling error signal,a manually tuning application for tuning the phase and amplitude of the cancelling signal was accomplished so that the cancelling result finally converged.In the end,with the system constructed above,some noise-cancellation experiments were designed and done to validate the cancelling result of this system.The result showed that,objectively 10~25dB reduction has been achieved in the target zone.