Add dB scale

zonnewaarneming.py

@@ -37,6 +37,8 @@ def set_stoprequest(event):
 signal = 0.
 prev_signal = 0.
 
+y_scale_is_logarithmic = False
+
 datafile = open(f"data{int(Time.now().unix)}.txt", "w")
 print("Time (UTC),separation (deg),azimuth from north (deg), elevation (deg), signal, source", file=datafile)
 
@@ -180,6 +182,7 @@ while not stoprequest:
         maxsignal = signal
     if signal < minsignal:
         minsignal = signal
+    noiselevel = 75 # TODO: infer this from data
 
     scatter_data = scatterplot.get_offsets()
     scatter_data = np.vstack((scatter_data, [separation.deg, signal]))
@@ -188,10 +191,29 @@ while not stoprequest:
     prev_points = ax.scatter([separation.deg], [signal], s=50, color='red')
     ax.set_ylim((0.9 * minsignal, 1.1 * maxsignal))
 
-    if minsignal < 1000:
+    if (not y_scale_is_logarithmic) and minsignal < 1000:
         # Attenuator on
+        y_scale_is_logarithmic = True
         ax.set_yscale("log")
 
+        yticks = []
+        yticklabels = []
+        ytick = noiselevel
+        db = 0
+        while ytick < ax.get_ylim()[1]:
+            yticks.append(ytick)
+            yticklabels.append(f"{db} dB")
+            ytick *= 10**0.1
+            db += 1
+        while len(yticks) > 15:
+            yticks = yticks[::2]
+            yticklabels = yticklabels[::2]
+        ax.set_yticks(yticks)
+        ax.set_yticklabels(yticklabels)
+        ax.get_yaxis().set_tick_params(which='minor', size=0)
+        ax.get_yaxis().set_tick_params(which='minor', width=0)
+        ax.set_ylabel("Relatieve intensiteit")
+
     update_legend(ax, closest_source)
 
     # show the plot