diff --git a/src/bnetz/bnetz.c b/src/bnetz/bnetz.c
index af3f82a..d9ccf3d 100644
--- a/src/bnetz/bnetz.c
+++ b/src/bnetz/bnetz.c
@@ -445,21 +445,23 @@ void bnetz_receive_tone(bnetz_t *bnetz, int bit)
 }
 
 /* A digit was received. */
-void bnetz_receive_telegramm(bnetz_t *bnetz, uint16_t telegramm, double level, double quality)
+void bnetz_receive_telegramm(bnetz_t *bnetz, uint16_t telegramm, double level_avg, double level_dev, double quality_avg)
 {
 	struct impulstelegramm *it;
 	int digit = 0;
 
 	/* drop any telegramm that is too bad */
-	if (quality < 0.2)
+	if (level_dev / level_avg > 0.2)
 		return;
 
+	PDEBUG_CHAN(DDSP, DEBUG_INFO, "RX Level: average=%.0f%% deviation=%.0f%% Quality: %.0f%%\n", level_avg * 100.0, level_dev / level_avg * 100.0, quality_avg * 100.0);
+
 	it = bnetz_telegramm2digit(telegramm);
 	if (it) {
 		digit = it->digit;
-		PDEBUG(DBNETZ, (bnetz->sender.loopback) ? DEBUG_NOTICE : DEBUG_INFO, "Received telegramm '%s' (RX Level: %.0f%% Quality=%.0f)\n", it->description, level * 100.0 + 0.5, quality * 100.0 + 0.5);
+		PDEBUG(DBNETZ, (bnetz->sender.loopback) ? DEBUG_NOTICE : DEBUG_INFO, "Received telegramm '%s'\n", it->description);
 	} else {
-		PDEBUG(DBNETZ, DEBUG_DEBUG, "Received unknown telegramm digit '0x%04x' (RX Level: %.0f%% Quality=%.0f) (might be radio noise)\n", telegramm, level * 100.0 + 0.5, quality * 100.0 + 0.5);
+		PDEBUG(DBNETZ, DEBUG_DEBUG, "Received unknown telegramm digit '0x%04x' (might be radio noise)\n", telegramm);
 		return;
 	}
 
diff --git a/src/bnetz/bnetz.h b/src/bnetz/bnetz.h
index 39d979c..8f6cd64 100644
--- a/src/bnetz/bnetz.h
+++ b/src/bnetz/bnetz.h
@@ -103,6 +103,6 @@ int bnetz_create(int kanal, const char *audiodev, int use_sdr, int samplerate, d
 void bnetz_destroy(sender_t *sender);
 void bnetz_loss_indication(bnetz_t *bnetz);
 void bnetz_receive_tone(bnetz_t *bnetz, int bit);
-void bnetz_receive_telegramm(bnetz_t *bnetz, uint16_t telegramm, double level, double quality);
+void bnetz_receive_telegramm(bnetz_t *bnetz, uint16_t telegramm, double level_avg, double level_dev, double quality_avg);
 const char *bnetz_get_telegramm(bnetz_t *bnetz);
 
diff --git a/src/bnetz/dsp.c b/src/bnetz/dsp.c
index 59b618c..00a37ec 100644
--- a/src/bnetz/dsp.c
+++ b/src/bnetz/dsp.c
@@ -161,6 +161,7 @@ static void fsk_receive_tone(bnetz_t *bnetz, int bit, int goodtone, double level
 /* Collect 16 data bits (digit) and check for sync mark '01110'. */
 static void fsk_receive_bit(void *inst, int bit, double quality, double level)
 {
+	double level_avg, level_dev, quality_avg;
 	bnetz_t *bnetz = (bnetz_t *)inst;
 	int i;
 
@@ -187,15 +188,24 @@ static void fsk_receive_bit(void *inst, int bit, double quality, double level)
 		return;
 
 	/* average level and quality */
-	level = quality = 0;
+	level_avg = level_dev = quality_avg = 0;
 	for (i = 0; i < 16; i++) {
-		level += bnetz->rx_telegramm_level[i];
-		quality += bnetz->rx_telegramm_quality[i];
+		level_avg += bnetz->rx_telegramm_level[bnetz->rx_telegramm_qualidx];
+		quality_avg += bnetz->rx_telegramm_quality[bnetz->rx_telegramm_qualidx];
+		if (++bnetz->rx_telegramm_qualidx == 16)
+			bnetz->rx_telegramm_qualidx = 0;
 	}
-	level /= 16.0; quality /= 16.0;
+	level_avg /= 16.0; quality_avg /= 16.0;
+	for (i = 0; i < 16; i++) {
+		level = bnetz->rx_telegramm_level[bnetz->rx_telegramm_qualidx];
+		level_dev += (level - level_avg) * (level - level_avg);
+		if (++bnetz->rx_telegramm_qualidx == 16)
+			bnetz->rx_telegramm_qualidx = 0;
+	}
+	level_dev = sqrt(level_dev / 16.0);
 
 	/* send telegramm */
-	bnetz_receive_telegramm(bnetz, bnetz->rx_telegramm, level, quality);
+	bnetz_receive_telegramm(bnetz, bnetz->rx_telegramm, level_avg, level_dev, quality_avg);
 }
 
 /* Process received audio stream from radio unit. */