add spectrum plot

fourier.py

@@ -0,0 +1,39 @@
+import PyQt5
+import pyqtgraph as pg
+from pyqtgraph.Qt import QtGui, QtCore
+import numpy as np
+from scipy.signal import hilbert
+from scipy.fft import fft, fftfreq
+from scipy.signal.windows import hamming
+
+a = 250000
+b = 450000
+ch1 = np.load("siglent_ch1.npy")[a:b]
+ch2 = np.load("siglent_ch2.npy")[a:b]
+
+ch1 = ch1 - np.mean(ch1)
+ch2 = ch2 - np.mean(ch2)
+
+out_samples = []
+prev_ref = ch1[0]
+for sample, ref in zip(ch1, ch2):
+	if prev_ref*ref < 0:
+		out_samples.append(sample)
+	prev_ref = ref
+
+
+app = QtGui.QApplication([])
+mainwindow = QtGui.QMainWindow()
+
+widget = pg.PlotWidget()
+mainwindow.setCentralWidget(widget)
+
+mainwindow.show()
+
+out_samples = out_samples*hamming(len(out_samples))
+
+widget.clear()
+widget.plot(2*473.6*fftfreq(len(out_samples))[:len(out_samples)//2], np.abs(fft(out_samples))[:len(out_samples)//2])
+
+app.exec_()
+