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Update filter generation script

This commit is contained in:
Geoffrey Merck 2020-05-24 07:44:38 +02:00
parent 5db1adb5ea
commit 26d055a67b
1 changed files with 8 additions and 8 deletions
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16
Tools/FMGenerateFilterCoefficients.py
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@ -17,30 +17,30 @@ f2 = 2700
rp = 0.2 rp = 0.2
# scaling factor in bits, do not change ! # scaling factor in bits, do not change !
q = 0 q = 15
# scaling factor as facor... # scaling factor as facor...
scaling_factor = 2**q scaling_factor = 2**q
# let's generate a sequence of 2nd order IIR filters # let's generate a sequence of 2nd order IIR filters
sos = signal.cheby1(3,rp,[f1, f2],'bandpass', output='sos', fs=fs) sos = signal.cheby1(3,rp,[f1, f2],'bandpass', output='sos', fs=fs)
#sos = signal.cheby1(1, rp, 2122, 'lowpass', output='sos', fs=fs) #deemphasis filter #os = signal.cheby1(4, rp, f2, 'lowpass', output='sos', fs=fs) #deemphasis filter
#sos = signal.cheby1(1, rp, 2122, 'highpass', output='sos', fs=fs) #deemphasis filter #sos = signal.cheby1(1, rp, 2122, 'highpass', output='sos', fs=fs) #deemphasis filter
#sos = np.round((sos) * scaling_factor) sosrounded = np.round((sos) * scaling_factor)
# print coefficients # print coefficients
for biquad in sos: for biquad in sosrounded:
for coeff in biquad: for coeff in biquad:
#print(int(coeff),",",sep="",end="") print(int(coeff),",",sep="",end="")
print((coeff),",",sep="",end="") #print((coeff),",",sep="",end="")
print("") print("")
# plot the frequency response # plot the frequency response
b,a = signal.sos2tf(sos) b,a = signal.sos2tf(sos)
w,h = signal.freqz(b,a) w,h = signal.freqz(b,a, worN=2048)
pl.plot(w/np.pi/2*fs,20*np.log(np.abs(h))) pl.plot(w/np.pi/2*fs,20*np.log(np.abs(h)))
pl.xlabel('frequency/Hz'); pl.xlabel('frequency/Hz');
pl.ylabel('gain/dB'); pl.ylabel('gain/dB');
pl.ylim(top=1,bottom=-20); pl.ylim(top=1,bottom=-30);
pl.xlim(left=250, right=12000); pl.xlim(left=250, right=12000);
pl.show() pl.show()