Added time of flight data analysis script

Used to compare expected time of flight to measured when using epoxyed desoldered hc-sr04 ultrasonic transducers.

epoxy_transducer/tof_data.py

@@ -0,0 +1,40 @@
+import numpy as np
+import matplotlib.pyplot as plt
+
+num_meas = 4
+
+# speed of sound m/s
+sos = 1500
+
+# depth of the tub in mm
+tub_depth = 690
+
+# distances from the top measured at in mm
+distance = [0,138,276,414]
+
+# distance from the bottom
+distance_to_bot = np.empty(num_meas)
+for i in range(num_meas):
+    distance_to_bot[i] = tub_depth - distance[i]
+
+# time from pulse to reflection measuredin uS
+tof = [912,758,614,486]
+
+# tot distance traveled
+distance_traveled = np.empty(num_meas)
+for i in range(num_meas):
+    distance_traveled[i] = (690*2) - (distance[i] * 2)
+
+# ideal time from pulse to reflection measured uS
+tof_expected = np.empty(num_meas)
+for i in range(num_meas):
+    tof_expected[i] = ((distance_traveled[i] * 1e-3) / sos) * 1e6
+
+plt.figure(1)
+plt.plot(distance_to_bot, tof, label = 'tof measured in uS')
+plt.plot(distance_to_bot, tof_expected, label = 'tof expected in uS')
+plt.xlabel('Distance to bottom [mm]')
+plt.ylabel('Time [uS]')
+plt.title('Tof Data')
+plt.xlim(max(distance_to_bot),min(distance_to_bot))
+plt.legend()