Realization On Narrowband Active Noise Control System Based On DSP

Sound pollution exists in our daily life and industry environment, which has attracted a great deal of attention in recent years. The traditional passive noise control techniques are ineffective at low-frequency noise. Compared with traditional passive noise control techniques, active noise control (ANC) techniques have excellent low-frequency characteristics, which are very suitable for controlling of low-frequency especially narrowband low-frequency noise control occasion. These kinds of noises exist widely in rotating equipment and reciprocating motion of the mechanical equipment and most of them spread out through a duct, which relate to civil field, industrial field and military field. With the development of society and economy, noise pollution can't be ignored in the rapid development of three major areas. Because of the effective suppression of narrowband noise, lots of researches are carried out on narrowband active noise control system. These research works can be carried out both from theory and practical application. We take the realization of narrowband ANC system as the entry point, then, detailed analysis on narrowband ANC system and design the whole of the system. Main research works are as follows.Firstly, the theory of sound field refer to duct was analyzed, including acoustic waveguide theory and plane wave on duct environment, then, one-dimensional duct was designed for spreading narrowband low-frequency noise to simplify acoustic model, which was useful for realization of narrowband ANC system.Secondly, adaptive filter and active noise controller were researched, then, taken one-dimensional duct as the experimental platform and design feed forward narrowband active noise control system based on TMS320VC5509DSP.Thirdly, PC program was written to analyze the power spectrum of residual noise in real-time, and monitor noise reduction by MATLAB and sound level meter.Fourthly, according to the system was easy to divergent in real application, a scale factor was introduced to constrain system divergence, then, on this basis, a lot of experiments were done on duct noise and obtained good effect on noise reduction which proved the effectiveness of the system.Finally, problems of the application and corresponding solutions were analyzed on ANC system by comparing the kinds of experimental programs and phenomena on duct noise reduction.