Revert "Merge branch 'M17_AX25_FM'"

This reverts commit e1427e3e37, reversing
changes made to bcdba292eb.

Tools/PreEmphasis.py

@@ -1,51 +0,0 @@
-#based on https://github.com/gnuradio/gnuradio/blob/master/gr-analog/python/analog/fm_emph.py
-
-import math
-import cmath
-import numpy as np
-import scipy.signal as signal
-import pylab as pl
-
-tau = 750e-6
-fs = 8000
-fh = 2700
-
-# Digital corner frequencies
-w_cl = 1.0 / tau
-w_ch = 2.0 * math.pi * fh
-
-# Prewarped analog corner frequencies
-w_cla = 2.0 * fs * math.tan(w_cl / (2.0 * fs))
-w_cha = 2.0 * fs * math.tan(w_ch / (2.0 * fs))
-
-# Resulting digital pole, zero, and gain term from the bilinear
-# transformation of H(s) = (s + w_cla) / (s + w_cha) to
-# H(z) = b0 (1 - z1 z^-1)/(1 - p1 z^-1)
-kl = -w_cla / (2.0 * fs)
-kh = -w_cha / (2.0 * fs)
-z1 = (1.0 + kl) / (1.0 - kl)
-p1 = (1.0 + kh) / (1.0 - kh)
-b0 = (1.0 - kl) / (1.0 - kh)
-
-# Since H(s = infinity) = 1.0, then H(z = -1) = 1.0 and
-# this filter  has 0 dB gain at fs/2.0.
-# That isn't what users are going to expect, so adjust with a
-# gain, g, so that H(z = 1) = 1.0 for 0 dB gain at DC.
-w_0dB = 2.0 * math.pi * 0.0
-g =        abs(1.0 - p1 * cmath.rect(1.0, -w_0dB)) \
-/ (b0 * abs(1.0 - z1 * cmath.rect(1.0, -w_0dB)))
-
-btaps = [ g * b0 * 1.0, g * b0 * -z1, 0]
-ataps = [          1.0,          -p1, 0]
-
-taps = np.concatenate((btaps, ataps), axis=0)
-print("Taps")
-print(*taps, "", sep=",", end="\n")
-
-f,h = signal.freqz(btaps,ataps, fs=fs)
-pl.plot(f, 20*np.log10(np.abs(h)))
-pl.xlabel('frequency/Hz')
-pl.ylabel('gain/dB')
-pl.ylim(top=30,bottom=0)
-pl.xlim(left=0, right=fh*2.5)
-pl.show()