Noise cancellation system with adaptive filter and two different sample rates

摘要

The system and method comprising: an adaptive filter 44 for receiving a digital noise signal 40 at a first sample rate and for generating a noise cancellation signal; and control circuitry 54, for generating a control signal at a second sample rate for application to the adaptive filter so as to adjust a filter characteristic. The second sample rate is lower than the first sample rate but is higher than a Nyquist sampling rate required to sample signals up to a desired cut-off frequency within the audio frequency range. The system may employ analog-digital converters 42 if the signal sources are not digital, and may use a decimator 52 to reduce signal sample rates. The first sample rate may vary from 100 kHz to over 1 MHz and the second sample rate from 50 kHz to less than 2 kHz. The system may find application in mobile phones, headphones, earphones etc..