Microcontroller-driven analogue filter for active noise control

Both feedforward and feedback control strategies are used in active noise and vibration control. Both approaches have their individual benefits and drawbacks, and their use depends on the application areas. The limitation in feedforward control is that the primary signal must be known before it can be attenuated actively. If this requirement is met, there is usually enough processing time available and adaptive digital systems can readily be used. Furthermore, the stability of feedforward control systems can be easily guaranteed whereas the feedback loop of a feedback control system inherently sets a limit for the stability [1]. When a coherent reference signal is difficult or even impossible to obtain, or is transient in nature, the feedback control is a more suitable approach.