How to decrease the sample rate properly on AN00162?
Posted: Thu May 31, 2018 5:24 am
Hi everyone,
I am developing an active noise cancellation headphone system on xCORE-200 Multichannel Audio platform, basing on the example: AN00162(Using the i2s library). And now I manage to reduce the noise of single frequencies(i.e. sine waves )from 100Hz - 1000Hz. However, when I change my noise signal to narrowband gaussian noise or just to a double-frequency signal,for example, a signal composed of 400Hz and 410Hz,my system doesn't work. In other words, it can't reduce the noise.
My project is based on LMS algorithm, which is implemented using xCORE-200 DSP library. I tried to increase the order of my FIR filter, but when the order is larger than 70, the project doesn't work——I mean the loudspeaker just make a sound like a bell ring instead of giving a anti-noise that cancels the primary noise, and there isn't any waves on the xSCOPE. I suspect this is due to the larger amount of calculations that need to be done when the filter order increases, and the xcore is unable to handle so much work. So I think maybe a lower sample rate could help solve this. I changed the sample rate from 48k to 24k,16k, 8k,6k,but none of these choices work, the same things happened: bell ring , no waves . So I want to know how to change the sample rate properly ?
Thanks!
cjf
I am developing an active noise cancellation headphone system on xCORE-200 Multichannel Audio platform, basing on the example: AN00162(Using the i2s library). And now I manage to reduce the noise of single frequencies(i.e. sine waves )from 100Hz - 1000Hz. However, when I change my noise signal to narrowband gaussian noise or just to a double-frequency signal,for example, a signal composed of 400Hz and 410Hz,my system doesn't work. In other words, it can't reduce the noise.
My project is based on LMS algorithm, which is implemented using xCORE-200 DSP library. I tried to increase the order of my FIR filter, but when the order is larger than 70, the project doesn't work——I mean the loudspeaker just make a sound like a bell ring instead of giving a anti-noise that cancels the primary noise, and there isn't any waves on the xSCOPE. I suspect this is due to the larger amount of calculations that need to be done when the filter order increases, and the xcore is unable to handle so much work. So I think maybe a lower sample rate could help solve this. I changed the sample rate from 48k to 24k,16k, 8k,6k,but none of these choices work, the same things happened: bell ring , no waves . So I want to know how to change the sample rate properly ?
Thanks!
cjf