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Altera_Forum's avatar
Altera_Forum
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11 years ago

fir filter for fsk demodulator

Hi, i've realized an i_q demodulator for fsk message. The frequencies for the 0 and for the 1 are spaced 400Hz; the baud rate is up 200baud. The frequencies are in the audio range (for example F...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
11 years ago

this fir cuts at 200Hz and achieves -40dB at 6300 and should do for worst case

h = fir2(100,[0 200/200000 4500/200000 .5]*2,[1 1 0 0]);

h = h/sum(h);

freqz(h,1,0:.1:6300,200000)