4th test

README.md

@@ -30,6 +30,7 @@ ENABLE_BOOT_BEEPS             := 0       give user audio feedback on volume knob
 ENABLE_COMPANDER              := 1       compander option (per channel)
 ENABLE_SHOW_CHARGE_LEVEL      := 1       show the charge level when the radio is on charge 
 ENABLE_REVERSE_BAT_SYMBOL     := 1       mirror the battery symbol on the status bar (+ pole on the right)
+ENABLE_AM_FIX                 := 1       dynamically adjust the front end gains when in AM mode to helo prevent AM demodulator saturation - ignore the on-screen RSSI (for now)
 ENABLE_AUDIO_BAR              := 0       experimental, display an audo bar level when TX'ing
 #ENABLE_SINGLE_VFO_CHAN       := 1       not yet implemented - single VFO on display when possible
 #ENABLE_BAND_SCOPE            := 1       not yet implemented - spectrum/pan-adapter

app/app.c

@@ -69,9 +69,15 @@ static uint16_t mixer     = 3;   //   0dB
 static uint16_t pga       = 6;   //  -3dB
 
 #ifdef ENABLE_AM_FIX
-	// computes the average RSSI level over several samples
+	// moving average RSSI buffer
-	static unsigned int avg_rssi_counter = 0;
+	struct {
-	static uint16_t     avg_rssi         = 0;
+		unsigned int index;
+		uint16_t     samples[10];   // 100ms long buffer (10ms RSSI sample rate)
+		uint16_t     sum;           // sum of all samples in the buffer
+	} moving_avg_rssi;
+
+	unsigned int rssi_peak_hold_val   = 0;
+	unsigned int rssi_peak_hold_count = 0;
 #endif
 
 static void APP_ProcessKey(KEY_Code_t Key, bool bKeyPressed, bool bKeyHeld);
@@ -426,8 +432,10 @@ void APP_StartListening(FUNCTION_Type_t Function)
 	#endif
 
 	#ifdef ENABLE_AM_FIX
-		avg_rssi_counter = 0;
+		// reset the moving average filter
-		avg_rssi         = 0;
+		memset(&moving_avg_rssi, 0, sizeof(moving_avg_rssi));
+		rssi_peak_hold_val   = 0;
+		rssi_peak_hold_count = 0;
 	#endif
 
 	gVFO_RSSI_Level[gEeprom.RX_CHANNEL == 0] = 0;
@@ -1359,7 +1367,7 @@ void APP_CheckKeys(void)
 		// REG_10 <15:0> 0x0038 Rx AGC Gain Table[0]. (Index Max->Min is 3,2,1,0,-1)
 		//
 		//         <9:8> = LNA Gain Short
-		//                 3 =   0dB
+		//                 3 =   0dB   < original value
 		//                 2 = -11dB
 		//                 1 = -16dB
 		//                 0 = -19dB
@@ -1370,19 +1378,19 @@ void APP_CheckKeys(void)
 		//                 5 =  -4dB
 		//                 4 =  -6dB
 		//                 3 =  -9dB
-		//                 2 = -14dB
+		//                 2 = -14dB   < original value
 		//                 1 = -19dB
 		//                 0 = -24dB
 		//
 		//         <4:3> = MIXER Gain
-		//                 3 =  0dB
+		//                 3 =   0dB   < original value
 		//                 2 =  -3dB
 		//                 1 =  -6dB
 		//                 0 =  -8dB
 		//
 		//         <2:0> = PGA Gain
 		//                 7 =   0dB
-		//                 6 =  -3dB
+		//                 6 =  -3dB   < original value
 		//                 5 =  -6dB
 		//                 4 =  -9dB
 		//                 3 = -15dB
@@ -1397,34 +1405,36 @@ void APP_CheckKeys(void)
 		register uint16_t new_pga       = pga;
 
 		// -86dBm, any higher and the AM demodulator starts to saturate
-		const uint16_t desired_rssi = (-86 + 160) * 2;
+		const uint16_t desired_rssi = (-86 + 160) * 2;   // dBm to ADC sample
 
 		// sample the current RSSI level
-		gCurrentRSSI = BK4819_GetRSSI();
+		uint16_t rssi = BK4819_GetRSSI(); // 9-bit value
+		//gCurrentRSSI = rssi;
+
+		// compute the moving average RSSI
+		moving_avg_rssi.sum -= moving_avg_rssi.samples[moving_avg_rssi.index];  // remove the oldest sample
+		moving_avg_rssi.sum += rssi;                                            // add the newest sample
+		moving_avg_rssi.samples[moving_avg_rssi.index] = rssi;                  // save the newest sample
+		if (++moving_avg_rssi.index >= ARRAY_SIZE(moving_avg_rssi.samples))     //
+			moving_avg_rssi.index = 0;                                          // wrap-a-round
 
 		// compute the average
-		avg_rssi += gCurrentRSSI;
+		rssi = moving_avg_rssi.sum / ARRAY_SIZE(moving_avg_rssi.samples);
-		if (++avg_rssi_counter < 16)	// 160ms - rate at which we adjust the front end gains
-			return;
-		avg_rssi /= avg_rssi_counter;
 
-		if (avg_rssi < (desired_rssi - 4))
+		if (rssi >= rssi_peak_hold_val)
-		{	// increase gain
+		{	// enter hold mode (pause any gain increases)
-			if (new_pga < 7)
+			rssi_peak_hold_val   = rssi;
-				new_pga++;
+			rssi_peak_hold_count = 50;  // 500ms
-			else
-			if (new_mixer < 3)
-				new_mixer++;
-			else
-			if (new_lna < 7)
-				new_lna++;
-			else
-			if (new_lna_short < 3)
-				new_lna_short++;
 		}
 		else
-		if (avg_rssi > (desired_rssi + 4))
+		if (rssi_peak_hold_count > 0)
+			rssi_peak_hold_count--;
+		else
+			rssi_peak_hold_val = rssi;
+
+		if (rssi > (desired_rssi + 4))
 		{	// decrease gain
+
 			if (new_pga > 6)
 				new_pga--;
 			else
@@ -1447,13 +1457,32 @@ void APP_CheckKeys(void)
 				new_mixer--;
 		}
 
-		avg_rssi_counter = 0;
+		if (moving_avg_rssi.index > 0)
-		avg_rssi         = 0;
+		{	// increase gain once every 100ms
+
+			if (rssi_peak_hold_count == 0)
+			{
+				if (rssi < (desired_rssi - 4))
+				{	// increase gain
+					if (new_pga < 7)
+						new_pga++;
+					else
+					if (new_mixer < 3)
+						new_mixer++;
+					else
+					if (new_lna < 7)
+						new_lna++;
+					else
+					if (new_lna_short < 3)
+						new_lna_short++;
+				}
+			}
+		}
 
 		if (lna_short == new_lna_short && lna == new_lna && mixer == new_mixer && pga == new_pga)
 			return;    // no change
 
-		// apply the adjusted gain settings
+		// apply the new gain settings to the front end
 
 		lna_short = new_lna_short;
 		lna       = new_lna;