Add images and equations for migration to wiki.

assets/filter.py

@@ -0,0 +1,36 @@
+import matplotlib.pyplot as plt
+import numpy as np
+from scipy import signal
+import math
+
+pktlen = 38144 / 4
+
+raw = np.memmap("sample.bin", dtype=np.uint8, offset=(17600<<1)+2048+256, mode='r')
+
+window = raw[:pktlen].copy()
+level = 127.4
+iq = ((level-(window.astype(np.float64))) / level).view(np.complex128)
+
+fig, subplots = plt.subplots(nrows=2)
+fig.set_size_inches(9,9*0.6180339887)
+
+(mag_plot, spec_plot) = subplots
+
+mag = np.abs(iq)
+
+filtered = np.correlate(mag, np.append(np.ones(78), -np.ones(78)))
+
+kernel = np.append(np.ones(78), -np.ones(78))
+mag_plot.step(np.arange(kernel.size), kernel)
+mag_plot.grid(axis='both')
+mag_plot.autoscale(tight=True)
+mag_plot.set_ylim(-1.125, 1.125)
+mag_plot.set_xlim(-5, 78*2 + 5)
+mag_plot.xaxis.set_ticks([0,39, 78, 117, 156])
+
+spec_plot.plot(filtered)
+spec_plot.grid(axis='both')
+spec_plot.autoscale(tight=True)
+
+plt.savefig('filter.png', dpi=96, transparent=True, bbox_inches="tight")
+# plt.show()