designing band stop filter..

[kr.sandeep]

hi guys .. i am a newbie here. i am designing a band stop filter fr my academic project.i will have to build a hardware prototype on ATMEGA 32 micrcontroller. i am going to design it using MATLAB fdatool and FIR least square to find coefficients. after that i will use filter coefficients to write a C code to be burned in microcntroller. i am also using proteus 7.7 for simulation of hardware.

so.. i want this stop band filter to filter out 50Hz mains humm noise from an audio signal.
s here are a few questions i would like to ask..

first of all will this ATMEGA32 microcontroller be able to provide enough computation resources to support this kind of audio application at all.. i mean the will inbuilt ADC be fast enough to do this..

how do i decide order of the filter, sampling frequency, F pass 1,Fstop1,Fstop 2,Fpass2 (well i guess Fstop1 and Fstop should be 49 and 51 for 50 Hz stop band if i am not wrong) in fdatool.

thanx for the help guys..

 

[barry]

There a lot of tools out there for determining filter order-just search the net. I'm not really familiar with the Atmel processors, but I'm not sure this ATMEGA is up to the task; first, it's only an 8-bit processor-that will impact your audio quality. Filters require a lot of multiplication and that device only has one multiplier, so that's going to slow you down.

As a first-order evaluation, I'd calculate the required filter size, and then estimate out how long it will take to calculate each sample output. (It's just a bunch of multiply-and-adds). Maybe if 8-bit resolution is acceptable, and you don't require too much bandwidth and the processor doesn't have to do anything else but filter, it might work.

 

[jamewhite86]

As a first-order evaluation, I'd calculate the required filter size, and then estimate out how long it will take to calculate each sample output.thanks for sharing the information.