diff --git a/app/app.c b/app/app.c
index bc4ca37..6b23d57 100644
--- a/app/app.c
+++ b/app/app.c
@@ -88,7 +88,7 @@ static void APP_update_rssi(const int vfo)
 
 	#ifdef ENABLE_AM_FIX
 		// add RF gain adjust compensation
-		if (g_current_vfo->channel.am_mode > 0 && g_eeprom.config.setting.am_fix)
+		if (g_current_vfo->channel.mod_mode != MOD_MODE_FM && g_eeprom.config.setting.am_fix)
 			rssi -= rssi_gain_diff[vfo];
 	#endif
 
@@ -527,7 +527,7 @@ bool APP_start_listening(void)
 	}
 
 	// AF gain - original QS values
-//	if (g_rx_vfo->channel.am_mode > 0)
+//	if (g_rx_vfo->channel.mod_mode != MOD_MODE_FM)
 //	{
 //		BK4819_write_reg(0x48, 0xB3A8);   // 1011 0011 1010 1000
 //	}
@@ -550,12 +550,12 @@ bool APP_start_listening(void)
 	#ifdef ENABLE_VOICE
 		#ifdef MUTE_AUDIO_FOR_VOICE
 			if (g_voice_write_index == 0)
-				AUDIO_set_mod_mode(g_rx_vfo->channel.am_mode);
+				AUDIO_set_mod_mode(g_rx_vfo->channel.mod_mode);
 		#else
-			AUDIO_set_mod_mode(g_rx_vfo->channel.am_mode);
+			AUDIO_set_mod_mode(g_rx_vfo->channel.mod_mode);
 		#endif
 	#else
-		AUDIO_set_mod_mode(g_rx_vfo->channel.am_mode);
+		AUDIO_set_mod_mode(g_rx_vfo->channel.mod_mode);
 	#endif
 
 	GPIO_SetBit(&GPIOC->DATA, GPIOC_PIN_SPEAKER);
@@ -2385,7 +2385,7 @@ void APP_time_slice_10ms(void)
 	#endif
 
 	#ifdef ENABLE_AM_FIX
-		if (g_rx_vfo->channel.am_mode > 0 && g_eeprom.config.setting.am_fix)
+		if (g_rx_vfo->channel.mod_mode != MOD_MODE_FM && g_eeprom.config.setting.am_fix)
 			AM_fix_10ms(g_rx_vfo_num);
 	#endif
 
diff --git a/app/main.c b/app/main.c
index e220c7e..ebf55c1 100644
--- a/app/main.c
+++ b/app/main.c
@@ -213,12 +213,8 @@ void processFKeyFunction(const key_code_t Key)
 
 			if (g_fkey_pressed)
 			{
-				#if 0
-					g_tx_vfo->channel.am_mode = (g_tx_vfo->am_mode + 1) & 1u;
-				#else
-					if (++g_tx_vfo->channel.am_mode >= 3)
-						g_tx_vfo->channel.am_mode = 0;
-				#endif
+				if (++g_tx_vfo->channel.mod_mode >= MOD_MODE_LEN)
+					g_tx_vfo->channel.mod_mode = 0;
 				g_request_save_channel = 1;
 			}
 			else
diff --git a/app/menu.c b/app/menu.c
index d798ad7..749d675 100644
--- a/app/menu.c
+++ b/app/menu.c
@@ -767,7 +767,7 @@ void MENU_AcceptSetting(void)
 			break;
 
 		case MENU_MOD_MODE:
-			g_tx_vfo->channel.am_mode = g_sub_menu_selection;
+			g_tx_vfo->channel.mod_mode = g_sub_menu_selection;
 			g_request_save_channel = 1;
 		return;
 /*
@@ -1234,7 +1234,7 @@ void MENU_ShowCurrentSetting(void)
 			break;
 
 		case MENU_MOD_MODE:
-			g_sub_menu_selection = g_tx_vfo->channel.am_mode;
+			g_sub_menu_selection = g_tx_vfo->channel.mod_mode;
 			break;
 /*
 #ifdef ENABLE_AM_FIX
@@ -1765,7 +1765,7 @@ static void MENU_Key_STAR(const bool key_pressed, const bool key_held)
 
 	RADIO_select_vfos();
 
-	if (IS_NOT_NOAA_CHANNEL(g_rx_vfo->channel_save) && g_rx_vfo->channel.am_mode == 0)
+	if (IS_NOT_NOAA_CHANNEL(g_rx_vfo->channel_save) && g_rx_vfo->channel.mod_mode == MOD_MODE_FM)
 	{
 		if (g_menu_cursor == MENU_RX_CTCSS || g_menu_cursor == MENU_RX_CDCSS)
 		{	// scan CTCSS or DCS to find the tone/code of the incoming signal
diff --git a/audio.c b/audio.c
index f104d50..7e68b40 100644
--- a/audio.c
+++ b/audio.c
@@ -77,16 +77,15 @@
 
 beep_type_t g_beep_to_play = BEEP_NONE;
 
-void AUDIO_set_mod_mode(const unsigned int mode)
+void AUDIO_set_mod_mode(const mod_mode_t mode)
 {
 	BK4819_af_type_t af_mode;
 	switch (mode)
 	{			
 		default:
-		case 0: af_mode = BK4819_AF_FM; break;
-		case 1: af_mode = BK4819_AF_AM; break;
-		case 2: af_mode = BK4819_AF_BASEBAND1; break;
-		case 3: af_mode = BK4819_AF_BASEBAND2; break;
+		case MOD_MODE_FM: af_mode = BK4819_AF_FM; break;
+		case MOD_MODE_AM: af_mode = BK4819_AF_AM; break;
+		case MOD_MODE_DSB: af_mode = BK4819_AF_BASEBAND1; break;
 	}
 	BK4819_SetAF(af_mode);
 }
@@ -338,7 +337,7 @@ void AUDIO_PlayBeep(beep_type_t Beep)
 			SYSTEM_DelayMs(Delay * 10);
 
 			if (g_current_function == FUNCTION_RECEIVE)
-				AUDIO_set_mod_mode(g_rx_vfo->channel.am_mode);
+				AUDIO_set_mod_mode(g_rx_vfo->channel.mod_mode);
 			
 			#ifdef ENABLE_FMRADIO
 				if (g_fm_radio_mode)
@@ -486,7 +485,7 @@ void AUDIO_PlayBeep(beep_type_t Beep)
 		// unmute the radios audio
 
 		if (g_current_function == FUNCTION_RECEIVE)
-			AUDIO_set_mod_mode(g_rx_vfo->channel.am_mode);
+			AUDIO_set_mod_mode(g_rx_vfo->channel.mod_mode);
 		
 		#ifdef ENABLE_FMRADIO
 			if (g_fm_radio_mode)
diff --git a/audio.h b/audio.h
index 8d04dd2..6181d93 100644
--- a/audio.h
+++ b/audio.h
@@ -20,6 +20,8 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+#include "settings.h"
+
 enum beep_type_e {
 	BEEP_NONE = 0,
 	BEEP_1KHZ_60MS_OPTIONAL,
@@ -36,7 +38,7 @@ typedef enum beep_type_e beep_type_t;
 
 extern beep_type_t g_beep_to_play;
 
-void AUDIO_set_mod_mode(const unsigned int mode);
+void AUDIO_set_mod_mode(const mod_mode_t mode);
 void AUDIO_PlayBeep(beep_type_t Beep);
 
 enum {
diff --git a/firmware.bin b/firmware.bin
index ad73f23..d753332 100644
Binary files a/firmware.bin and b/firmware.bin differ
diff --git a/firmware.packed.bin b/firmware.packed.bin
index 64b7cb5..9c23f7b 100644
Binary files a/firmware.packed.bin and b/firmware.packed.bin differ
diff --git a/functions.c b/functions.c
index 5b870d1..f08fb4f 100644
--- a/functions.c
+++ b/functions.c
@@ -51,7 +51,7 @@ void FUNCTION_Init(void)
 	{
 		g_current_code_type = g_selected_code_type;
 		if (g_css_scan_mode == CSS_SCAN_MODE_OFF)
-			g_current_code_type = (g_rx_vfo->channel.am_mode > 0) ? CODE_TYPE_NONE : g_rx_vfo->p_rx->code_type;
+			g_current_code_type = (g_rx_vfo->channel.mod_mode > 0) ? CODE_TYPE_NONE : g_rx_vfo->p_rx->code_type;
 	}
 	else
 		g_current_code_type = CODE_TYPE_CONTINUOUS_TONE;
diff --git a/radio.c b/radio.c
index b978bcf..2241b00 100644
--- a/radio.c
+++ b/radio.c
@@ -145,7 +145,7 @@ void RADIO_InitInfo(vfo_info_t *p_vfo, const uint8_t ChannelSave, const uint32_t
 	p_vfo->freq_in_channel              = 0xff;
 
 	if (ChannelSave == (FREQ_CHANNEL_FIRST + BAND2_108MHz))
-		p_vfo->channel.am_mode = 1;    // AM
+		p_vfo->channel.mod_mode = MOD_MODE_AM;
 
 	RADIO_ConfigureSquelchAndOutputPower(p_vfo);
 }
@@ -338,7 +338,7 @@ void RADIO_configure_channel(const unsigned int VFO, const unsigned int configur
 //		EEPROM_ReadBuffer(0x0F50 + (channel * 16), p_vfo->channel_name, 10);	// only 10 bytes used
 		memcpy(p_vfo->channel_name.name, &g_eeprom.config.channel_name[channel].name, sizeof(p_vfo->channel_name.name));
 
-	if (p_vfo->channel.am_mode > 0)
+	if (p_vfo->channel.mod_mode != MOD_MODE_FM)
 	{	// freq/chan is in AM mode
 		// disable stuff, even though it can all still be used with AM ???
 		p_vfo->channel.scrambler            = 0;
@@ -351,7 +351,7 @@ void RADIO_configure_channel(const unsigned int VFO, const unsigned int configur
 
 	#ifdef ENABLE_AM_FIX
 		AM_fix_reset(VFO);
-		if (p_vfo->channel.am_mode > 0 && g_eeprom.config.setting.am_fix)
+		if (p_vfo->channel.mod_mode != MOD_MODE_FM && g_eeprom.config.setting.am_fix)
 		{
 			AM_fix_10ms(VFO);
 		}
@@ -361,7 +361,7 @@ void RADIO_configure_channel(const unsigned int VFO, const unsigned int configur
 			BK4819_write_reg(0x13, (orig_lnas << 8) | (orig_lna << 5) | (orig_mixer << 3) | (orig_pga << 0));
 		}
 	#else
-		if (p_vfo->am_mode > 0)
+		if (p_vfo->mod_mode != MOD_MODE_FM)
 		{
 			BK4819_EnableAGC();
 		}
@@ -661,7 +661,7 @@ void RADIO_setup_registers(bool switch_to_function_foreground)
 					BK4819_SetFilterBandwidth(Bandwidth);
 					BK4819_EnableAFC();
 				#else
-					if (g_rx_vfo->channel.am_mode > 1)
+					if (g_rx_vfo->channel.mod_mode != MOD_MODE_FM)
 					{
 						BK4819_SetFilterBandwidth(BK4819_FILTER_BW_NARROWER); // sideband
 						BK4819_DisableAFC();
@@ -726,7 +726,7 @@ void RADIO_setup_registers(bool switch_to_function_foreground)
 	BK4819_set_GPIO_pin(BK4819_GPIO0_PIN28_RX_ENABLE, true);
 
 	// AF RX Gain and DAC
-//	if (g_rx_vfo->channel.am_mode > 0)
+//	if (g_rx_vfo->channel.mod_mode != MOD_MODE_FM)
 //	{
 //		BK4819_write_reg(0x48, 0xB3A8);   // 1011 0011 1010 1000
 //	}
@@ -748,12 +748,12 @@ void RADIO_setup_registers(bool switch_to_function_foreground)
 			#ifdef ENABLE_VOICE
 				#ifdef MUTE_AUDIO_FOR_VOICE
 					if (g_voice_write_index == 0)
-						AUDIO_set_mod_mode(g_rx_vfo->channel.am_mode);
+						AUDIO_set_mod_mode(g_rx_vfo->channel.mod_mode);
 				#else
-					AUDIO_set_mod_mode(g_rx_vfo->channel.am_mode);
+					AUDIO_set_mod_mode(g_rx_vfo->channel.mod_mode);
 				#endif
 			#else
-				AUDIO_set_mod_mode(g_rx_vfo->channel.am_mode);
+				AUDIO_set_mod_mode(g_rx_vfo->channel.mod_mode);
 			#endif
 		}
 	}
@@ -762,7 +762,7 @@ void RADIO_setup_registers(bool switch_to_function_foreground)
 
 	if (IS_NOT_NOAA_CHANNEL(g_rx_vfo->channel_save))
 	{
-		if (g_rx_vfo->channel.am_mode == 0)
+		if (g_rx_vfo->channel.mod_mode == MOD_MODE_FM)
 		{	// FM
 			uint8_t code_type = g_selected_code_type;
 			uint8_t code      = g_selected_code;
@@ -833,7 +833,7 @@ void RADIO_setup_registers(bool switch_to_function_foreground)
 			#endif
 			g_eeprom.config.setting.vox_enabled &&
 			IS_NOT_NOAA_CHANNEL(g_current_vfo->channel_save) &&
-			g_current_vfo->channel.am_mode == 0)
+			g_current_vfo->channel.mod_mode == MOD_MODE_FM)
 		{
 			RADIO_enable_vox(g_eeprom.config.setting.vox_level);
 			interrupt_mask |= BK4819_REG_3F_VOX_FOUND | BK4819_REG_3F_VOX_LOST;
@@ -843,7 +843,7 @@ void RADIO_setup_registers(bool switch_to_function_foreground)
 			BK4819_DisableVox();
 
 	// RX expander
-	BK4819_SetCompander((g_rx_vfo->channel.am_mode == 0 && g_rx_vfo->channel.compand >= 2) ? g_rx_vfo->channel.compand : 0);
+	BK4819_SetCompander((g_rx_vfo->channel.mod_mode == MOD_MODE_FM && g_rx_vfo->channel.compand >= 2) ? g_rx_vfo->channel.compand : 0);
 
 	BK4819_EnableDTMF();
 	interrupt_mask |= BK4819_REG_3F_DTMF_5TONE_FOUND;
@@ -932,7 +932,7 @@ void RADIO_enableTX(const bool fsk_tx)
 					BK4819_SetFilterBandwidth(Bandwidth);
 					BK4819_EnableAFC();
 				#else
-					if (g_current_vfo->channel.am_mode > 1)
+					if (g_current_vfo->channel.mod_mode == MOD_MODE_DSB)
 					{
 						BK4819_SetFilterBandwidth(BK4819_FILTER_BW_NARROWER); // sideband
 						BK4819_DisableAFC();
@@ -954,7 +954,7 @@ void RADIO_enableTX(const bool fsk_tx)
 	// so MAKE SURE that DTMF is disabled - until needed
 	BK4819_DisableDTMF();
 
-	BK4819_SetCompander((!fsk_tx && g_rx_vfo->channel.am_mode == 0 && (g_rx_vfo->channel.compand == 1 || g_rx_vfo->channel.compand >= 3)) ? g_rx_vfo->channel.compand : 0);
+	BK4819_SetCompander((!fsk_tx && g_rx_vfo->channel.mod_mode == MOD_MODE_FM && (g_rx_vfo->channel.compand == 1 || g_rx_vfo->channel.compand >= 3)) ? g_rx_vfo->channel.compand : 0);
 
 	BK4819_set_rf_frequency(g_current_vfo->p_tx->frequency, false);
 	BK4819_set_rf_filter_path(g_current_vfo->p_tx->frequency);
@@ -1066,7 +1066,7 @@ void RADIO_PrepareTX(void)
  	g_current_vfo = (g_eeprom.config.setting.cross_vfo == CROSS_BAND_OFF) ? g_rx_vfo : &g_vfo_info[g_eeprom.config.setting.tx_vfo_num];
 
 	#ifndef ENABLE_TX_WHEN_AM
-		if (g_current_vfo->channel.am_mode > 0)
+		if (g_current_vfo->channel.mod_mode != MOD_MODE_FM)
 		{	// not allowed to TX if not in FM mode
 			State = VFO_STATE_TX_DISABLE;
 		}
diff --git a/settings.h b/settings.h
index a6a6709..19ec3a6 100644
--- a/settings.h
+++ b/settings.h
@@ -24,6 +24,14 @@
 #include "dcs.h"
 #include "frequencies.h"
 
+enum mod_mode_e {
+	MOD_MODE_FM = 0,
+	MOD_MODE_AM,
+	MOD_MODE_DSB,
+	MOD_MODE_LEN
+};
+typedef enum mod_mode_e mod_mode_t;
+
 enum pwr_on_display_mode_e {
 	PWR_ON_DISPLAY_MODE_FULL_SCREEN = 0,
 	PWR_ON_DISPLAY_MODE_MESSAGE,
@@ -191,10 +199,10 @@ typedef struct {
 		uint8_t unused3:2;                   //
 	#endif
 	#if 0
-		uint8_t am_mode:1;                   //  FM/AM
+		uint8_t mod_mode:1;                  //  FM/AM
 		uint8_t unused4:3;                   //
 	#else                          
-		uint8_t am_mode:2;                   //  FM/AM/DSB
+		uint8_t mod_mode:2;                  //  FM/AM/DSB
 		uint8_t unused4:2;                   //
 	#endif
 	// [12]
diff --git a/ui/aircopy.c b/ui/aircopy.c
index 3efdd8e..3dd0ef5 100644
--- a/ui/aircopy.c
+++ b/ui/aircopy.c
@@ -19,6 +19,7 @@
 #include "external/printf/printf.h"
 #include "misc.h"
 #include "radio.h"
+#include "settings.h"
 #include "ui/aircopy.h"
 #include "ui/helper.h"
 #include "ui/inputbox.h"
diff --git a/ui/main.c b/ui/main.c
index 40b00eb..628534b 100644
--- a/ui/main.c
+++ b/ui/main.c
@@ -820,15 +820,15 @@ void UI_DisplayMain(void)
 		// ************
 
 		str[0] = '\0';
-		if (g_vfo_info[vfo_num].channel.am_mode > 0)
+		if (g_vfo_info[vfo_num].channel.mod_mode != MOD_MODE_FM)
 		{
-			//strcpy(str, g_sub_menu_mod_mode[g_vfo_info[vfo_num].channel.am_mode]);
-			switch (g_vfo_info[vfo_num].channel.am_mode)
+			//strcpy(str, g_sub_menu_mod_mode[g_vfo_info[vfo_num].channel.mod_mode]);
+			switch (g_vfo_info[vfo_num].channel.mod_mode)
 			{
 				default:
-				case 0: strcpy(str, "FM"); break;
-				case 1: strcpy(str, "AM"); break;
-				case 2: strcpy(str, "DS"); break;
+				case MOD_MODE_FM:  strcpy(str, "FM"); break;
+				case MOD_MODE_AM:  strcpy(str, "AM"); break;
+				case MOD_MODE_DSB: strcpy(str, "DS"); break;
 			}
 		}
 		else
@@ -844,7 +844,7 @@ void UI_DisplayMain(void)
 		#ifdef ENABLE_TX_WHEN_AM
 			if (state == VFO_STATE_NORMAL || state == VFO_STATE_ALARM)
 		#else
-			if ((state == VFO_STATE_NORMAL || state == VFO_STATE_ALARM) && g_vfo_info[vfo_num].channel.am_mode == 0) // TX allowed only when FM
+			if ((state == VFO_STATE_NORMAL || state == VFO_STATE_ALARM) && g_vfo_info[vfo_num].channel.mod_mode == MOD_MODE_FM) // TX allowed only when FM
 		#endif
 		{
 			if (FREQUENCY_tx_freq_check(g_vfo_info[vfo_num].p_tx->frequency) == 0)
@@ -934,7 +934,7 @@ void UI_DisplayMain(void)
 
 		#if defined(ENABLE_AM_FIX) && defined(ENABLE_AM_FIX_SHOW_DATA)
 			// show the AM-FIX debug data
-			if (rx && g_vfo_info[g_rx_vfo_num].am_mode > 0 && g_eeprom.config.setting.am_fix)
+			if (rx && g_vfo_info[g_rx_vfo_num].mod_mode != MOD_MODE_FM && g_eeprom.config.setting.am_fix)
 			{
 				g_center_line = CENTER_LINE_AM_FIX_DATA;
 				AM_fix_print_data(g_rx_vfo_num, str);