try to measure mpx power

lib/bs412.c

@@ -0,0 +1,23 @@
+#include "bs412.h"
+
+void init_modulation_power_measure(MPXPowerMeasurement* mpx, int sample_rate) {
+	mpx->i = 0;
+	mpx->sample = 0;
+	mpx->sample_rate = sample_rate;
+}
+
+float measure_mpx(MPXPowerMeasurement* mpx, int deviation) {
+	mpx->sample += 20*log10f(deviation/19);
+	mpx->i++;
+
+	if (mpx->i >= mpx->sample_rate) {
+		float modulation_power = mpx->sample/mpx->i;
+
+		mpx->sample = 0.0f;
+		mpx->i = 0;
+
+		return modulation_power;
+	} else {
+		return mpx->sample/mpx->i;
+	}
+}

lib/bs412.h

@@ -0,0 +1,13 @@
+#pragma once
+#include <math.h>
+
+typedef struct
+{
+    int i;
+    int sample_rate;
+    float sample;
+} MPXPowerMeasurement;
+
+void init_modulation_power_measure(MPXPowerMeasurement *mpx, int sample_rate);
+
+float measure_mpx(MPXPowerMeasurement *mpx, int deviation);