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# Simple digital FIR filter design

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#### cafukarfoo

##### Full Member level 3
digital fir filter design

Hello All,

I am new to DSP.

I would like to understand from scratch how to design a Simple digital FIR filter.

I would really appreciate if you can provide me some guidance here. Or any example will be really good? Thanks.

for FIR,

First u have to calculate coefficient h{n} = sin( 2*pi*n*f/FS)/(n*pi)
where f = fut off frequency
FS = sampling frequency
n = 0 to M-1; M = no coefficient; lenth of impulse response or filter kernel length

If M is more then ur roll off of freq response is sharper.
M = 3.3*FS/(Fstop -Fpass)
Fstop = stop band freq of transition band
Fpass = pass band freq of transition band
(Fstop -Fpass) = width of transition band

3.3 that is depend on ur window type

now do convolution between input and h{n} up to the lenth of L = N+M-1
N = no of input sample

See tha attachment

hi

i want a help that how this formula is satisfied .........

lenth of L = N+M-1
Q: Is this length of filter , than tell me how we satisfy this formula........

beat regards

M is the length of filter, and L is the length of the response of input data.

Ryan

dear

what about ' N ' , here

kindly explain it to me clearly............. if possible with diagram
for the concept..

regards

'N' is the number of input sample.

Ryan

hi u can use the book digital signal processing by "oppeinheim and schafer" or by "proakis and monalakis"

if u can get digital signal processing by ramesh babu there given idea on how to design filters using matlab and from that u can understand and u can implement the filter in hdl coding. if u can get digitalsignal processingforFPGA book then u can get coding for the filters in that.

bye

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