Move helper script to separate folder

Tools/FMGenerateFilterCoefficients.py

@@ -0,0 +1,46 @@
+# based on https://github.com/berndporr/iir_fixed_point/blob/master/gen_coeff.py
+
+import numpy as np
+import scipy.signal as signal
+import pylab as pl
+
+# Calculate the coefficients for a pure fixed point
+# integer filter
+
+# sampling rate
+fs = 24000
+
+# cutoffs
+f1 = 300
+f2 = 2700
+# ripple
+rp = 0.2
+
+# scaling factor in bits, do not change !
+q = 0
+# scaling factor as facor...
+scaling_factor = 2**q
+
+# 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(1, rp, 2122, 'lowpass', 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)
+
+# print coefficients
+for biquad in sos:
+    for coeff in biquad:
+        #print(int(coeff),",",sep="",end="")
+        print((coeff),",",sep="",end="")
+    print("")
+
+# plot the frequency response
+b,a = signal.sos2tf(sos)
+w,h = signal.freqz(b,a)
+pl.plot(w/np.pi/2*fs,20*np.log(np.abs(h)))
+pl.xlabel('frequency/Hz');
+pl.ylabel('gain/dB');
+pl.ylim(top=1,bottom=-20);
+pl.xlim(left=250, right=12000);
+pl.show()