From 3b404fb35acf81de7b628b95b2682a55defb04a8 Mon Sep 17 00:00:00 2001
From: Piotr Wilkon <sq8vps@gmail.com>
Date: Thu, 31 Aug 2023 17:48:32 +0200
Subject: [PATCH] modems working

---
 .cproject             | 26 +++++++------
 F103C8T6_DIGI_USB.xml |  2 +-
 Src/ax25.c            | 42 ++++++--------------
 Src/config.c          |  8 ++--
 Src/digipeater.c      |  4 +-
 Src/drivers/modem.c   | 90 ++++++++++++++++++++-----------------------
 Src/fx25.c            | 19 ++-------
 Src/main.c            |  2 +-
 Src/terminal.c        | 10 ++---
 9 files changed, 84 insertions(+), 119 deletions(-)

diff --git a/.cproject b/.cproject
index 827fe34..6d3ce3d 100644
--- a/.cproject
+++ b/.cproject
@@ -17,16 +17,16 @@
 				<configuration artifactExtension="elf" artifactName="${ProjName}" buildArtefactType="org.eclipse.cdt.build.core.buildArtefactType.exe" buildProperties="org.eclipse.cdt.build.core.buildArtefactType=org.eclipse.cdt.build.core.buildArtefactType.exe,org.eclipse.cdt.build.core.buildType=org.eclipse.cdt.build.core.buildType.debug" cleanCommand="rm -rf" description="" id="fr.ac6.managedbuild.config.gnu.cross.exe.debug.785246917" name="Debug" parent="fr.ac6.managedbuild.config.gnu.cross.exe.debug" postannouncebuildStep="Generating hex and Printing size information:" postbuildStep="arm-none-eabi-objcopy -O ihex &quot;${BuildArtifactFileBaseName}.elf&quot; &quot;${BuildArtifactFileBaseName}.hex&quot; &amp;&amp; arm-none-eabi-size &quot;${BuildArtifactFileName}&quot;">
 					<folderInfo id="fr.ac6.managedbuild.config.gnu.cross.exe.debug.785246917." name="/" resourcePath="">
 						<toolChain id="fr.ac6.managedbuild.toolchain.gnu.cross.exe.debug.2013979193" name="Ac6 STM32 MCU GCC" superClass="fr.ac6.managedbuild.toolchain.gnu.cross.exe.debug">
-							<option id="fr.ac6.managedbuild.option.gnu.cross.prefix.382830450" name="Prefix" superClass="fr.ac6.managedbuild.option.gnu.cross.prefix" value="arm-none-eabi-" valueType="string"/>
-							<option id="fr.ac6.managedbuild.option.gnu.cross.mcu.66405555" name="Mcu" superClass="fr.ac6.managedbuild.option.gnu.cross.mcu" value="STM32F103C8Tx" valueType="string"/>
-							<option id="fr.ac6.managedbuild.option.gnu.cross.board.1729153140" name="Board" superClass="fr.ac6.managedbuild.option.gnu.cross.board" value="F103C8T6_DIGI_USB" valueType="string"/>
-							<option id="fr.ac6.managedbuild.option.gnu.cross.core.1083960614" name="Core" superClass="fr.ac6.managedbuild.option.gnu.cross.core" valueType="stringList">
+							<option id="fr.ac6.managedbuild.option.gnu.cross.prefix.382830450" name="Prefix" superClass="fr.ac6.managedbuild.option.gnu.cross.prefix" useByScannerDiscovery="false" value="arm-none-eabi-" valueType="string"/>
+							<option id="fr.ac6.managedbuild.option.gnu.cross.mcu.66405555" name="Mcu" superClass="fr.ac6.managedbuild.option.gnu.cross.mcu" useByScannerDiscovery="false" value="STM32F103C8Tx" valueType="string"/>
+							<option id="fr.ac6.managedbuild.option.gnu.cross.board.1729153140" name="Board" superClass="fr.ac6.managedbuild.option.gnu.cross.board" useByScannerDiscovery="false" value="F103C8T6_DIGI_USB" valueType="string"/>
+							<option id="fr.ac6.managedbuild.option.gnu.cross.core.1083960614" name="Core" superClass="fr.ac6.managedbuild.option.gnu.cross.core" useByScannerDiscovery="false" valueType="stringList">
 								<listOptionValue builtIn="false" value="ARM Cortex-M3"/>
 								<listOptionValue builtIn="false" value="CM3"/>
 							</option>
-							<option id="fr.ac6.managedbuild.option.gnu.cross.instructionSet.1656935294" name="Instruction Set" superClass="fr.ac6.managedbuild.option.gnu.cross.instructionSet" value="fr.ac6.managedbuild.option.gnu.cross.instructionSet.thumbII" valueType="enumerated"/>
-							<option id="fr.ac6.managedbuild.option.gnu.cross.fpu.1493691602" name="Floating point hardware" superClass="fr.ac6.managedbuild.option.gnu.cross.fpu" value="fr.ac6.managedbuild.option.gnu.cross.fpu.no" valueType="enumerated"/>
-							<option id="fr.ac6.managedbuild.option.gnu.cross.floatabi.2025609880" name="Floating-point ABI" superClass="fr.ac6.managedbuild.option.gnu.cross.floatabi" value="fr.ac6.managedbuild.option.gnu.cross.floatabi.soft" valueType="enumerated"/>
+							<option id="fr.ac6.managedbuild.option.gnu.cross.instructionSet.1656935294" name="Instruction Set" superClass="fr.ac6.managedbuild.option.gnu.cross.instructionSet" useByScannerDiscovery="false" value="fr.ac6.managedbuild.option.gnu.cross.instructionSet.thumbII" valueType="enumerated"/>
+							<option id="fr.ac6.managedbuild.option.gnu.cross.fpu.1493691602" name="Floating point hardware" superClass="fr.ac6.managedbuild.option.gnu.cross.fpu" useByScannerDiscovery="false" value="fr.ac6.managedbuild.option.gnu.cross.fpu.no" valueType="enumerated"/>
+							<option id="fr.ac6.managedbuild.option.gnu.cross.floatabi.2025609880" name="Floating-point ABI" superClass="fr.ac6.managedbuild.option.gnu.cross.floatabi" useByScannerDiscovery="false" value="fr.ac6.managedbuild.option.gnu.cross.floatabi.soft" valueType="enumerated"/>
 							<targetPlatform archList="all" binaryParser="org.eclipse.cdt.core.ELF" id="fr.ac6.managedbuild.targetPlatform.gnu.cross.2146232636" isAbstract="false" osList="all" superClass="fr.ac6.managedbuild.targetPlatform.gnu.cross"/>
 							<builder buildPath="${workspace_loc:/F103C8T6_DIGI_USB}/Debug" id="fr.ac6.managedbuild.builder.gnu.cross.458407908" keepEnvironmentInBuildfile="false" managedBuildOn="true" name="Gnu Make Builder" parallelBuildOn="true" parallelizationNumber="optimal" superClass="fr.ac6.managedbuild.builder.gnu.cross">
 								<outputEntries>
@@ -53,6 +53,8 @@
 								</option>
 								<option id="fr.ac6.managedbuild.gnu.c.compiler.option.misc.other.1107445133" superClass="fr.ac6.managedbuild.gnu.c.compiler.option.misc.other" useByScannerDiscovery="false" value="-fmessage-length=0" valueType="string"/>
 								<option id="gnu.c.compiler.option.dialect.std.2115782942" name="Language standard" superClass="gnu.c.compiler.option.dialect.std" useByScannerDiscovery="true" value="gnu.c.compiler.dialect.default" valueType="enumerated"/>
+								<option id="gnu.c.compiler.option.warnings.wconversion.357268975" name="Implicit conversion warnings (-Wconversion)" superClass="gnu.c.compiler.option.warnings.wconversion" useByScannerDiscovery="false" value="false" valueType="boolean"/>
+								<option id="gnu.c.compiler.option.warnings.extrawarn.1997689762" name="Extra warnings (-Wextra)" superClass="gnu.c.compiler.option.warnings.extrawarn" useByScannerDiscovery="false" value="true" valueType="boolean"/>
 								<inputType id="fr.ac6.managedbuild.tool.gnu.cross.c.compiler.input.c.1385058365" superClass="fr.ac6.managedbuild.tool.gnu.cross.c.compiler.input.c"/>
 								<inputType id="fr.ac6.managedbuild.tool.gnu.cross.c.compiler.input.s.901665218" superClass="fr.ac6.managedbuild.tool.gnu.cross.c.compiler.input.s"/>
 							</tool>
@@ -77,10 +79,10 @@
 								<inputType id="fr.ac6.managedbuild.tool.gnu.cross.cpp.compiler.input.s.314001530" superClass="fr.ac6.managedbuild.tool.gnu.cross.cpp.compiler.input.s"/>
 							</tool>
 							<tool id="fr.ac6.managedbuild.tool.gnu.cross.c.linker.949266977" name="MCU GCC Linker" superClass="fr.ac6.managedbuild.tool.gnu.cross.c.linker">
-								<option id="fr.ac6.managedbuild.tool.gnu.cross.c.linker.script.100896041" name="Linker Script (-T)" superClass="fr.ac6.managedbuild.tool.gnu.cross.c.linker.script" value="../STM32F103C8Tx_FLASH.ld" valueType="string"/>
-								<option id="gnu.c.link.option.libs.1305202629" name="Libraries (-l)" superClass="gnu.c.link.option.libs"/>
-								<option id="gnu.c.link.option.paths.1292687187" name="Library search path (-L)" superClass="gnu.c.link.option.paths"/>
-								<option id="gnu.c.link.option.ldflags.2131178816" name="Linker flags" superClass="gnu.c.link.option.ldflags" value="-specs=nosys.specs -specs=nano.specs" valueType="string"/>
+								<option id="fr.ac6.managedbuild.tool.gnu.cross.c.linker.script.100896041" name="Linker Script (-T)" superClass="fr.ac6.managedbuild.tool.gnu.cross.c.linker.script" useByScannerDiscovery="false" value="../STM32F103C8Tx_FLASH.ld" valueType="string"/>
+								<option id="gnu.c.link.option.libs.1305202629" name="Libraries (-l)" superClass="gnu.c.link.option.libs" useByScannerDiscovery="false"/>
+								<option id="gnu.c.link.option.paths.1292687187" name="Library search path (-L)" superClass="gnu.c.link.option.paths" useByScannerDiscovery="false"/>
+								<option id="gnu.c.link.option.ldflags.2131178816" name="Linker flags" superClass="gnu.c.link.option.ldflags" useByScannerDiscovery="false" value="-specs=nosys.specs -specs=nano.specs" valueType="string"/>
 								<option id="gnu.c.link.option.other.623842724" name="Other options (-Xlinker [option])" superClass="gnu.c.link.option.other" useByScannerDiscovery="false"/>
 								<inputType id="cdt.managedbuild.tool.gnu.c.linker.input.751662654" superClass="cdt.managedbuild.tool.gnu.c.linker.input">
 									<additionalInput kind="additionalinputdependency" paths="$(USER_OBJS)"/>
@@ -100,7 +102,7 @@
 							</tool>
 							<tool id="fr.ac6.managedbuild.tool.gnu.archiver.1989184041" name="MCU GCC Archiver" superClass="fr.ac6.managedbuild.tool.gnu.archiver"/>
 							<tool id="fr.ac6.managedbuild.tool.gnu.cross.assembler.1762903833" name="MCU GCC Assembler" superClass="fr.ac6.managedbuild.tool.gnu.cross.assembler">
-								<option id="gnu.both.asm.option.include.paths.1278058431" name="Include paths (-I)" superClass="gnu.both.asm.option.include.paths"/>
+								<option id="gnu.both.asm.option.include.paths.1278058431" name="Include paths (-I)" superClass="gnu.both.asm.option.include.paths" useByScannerDiscovery="false"/>
 								<inputType id="cdt.managedbuild.tool.gnu.assembler.input.632714311" superClass="cdt.managedbuild.tool.gnu.assembler.input"/>
 								<inputType id="fr.ac6.managedbuild.tool.gnu.cross.assembler.input.1298773058" superClass="fr.ac6.managedbuild.tool.gnu.cross.assembler.input"/>
 							</tool>
diff --git a/F103C8T6_DIGI_USB.xml b/F103C8T6_DIGI_USB.xml
index cf0913b..a09e329 100644
--- a/F103C8T6_DIGI_USB.xml
+++ b/F103C8T6_DIGI_USB.xml
@@ -12,7 +12,7 @@
 <targetDefinitions>
   <board id="f103c8t6_digi_usb">
     <name>F103C8T6_DIGI_USB</name>
-    <dbgIF>JTAG</dbgIF>
+    <dbgIF>SWD</dbgIF>
     <dbgDEV>ST-Link</dbgDEV>
     <mcuId>stm32f103c8tx</mcuId>
   </board>
diff --git a/Src/ax25.c b/Src/ax25.c
index d7191ef..c2e71fe 100644
--- a/Src/ax25.c
+++ b/Src/ax25.c
@@ -139,7 +139,7 @@ struct RxState
 #endif
 };
 
-static volatile struct RxState rxState[MODEM_MAX_DEMODULATOR_COUNT];
+static struct RxState rxState[MODEM_MAX_DEMODULATOR_COUNT];
 
 static uint16_t lastCrc = 0; //CRC of the last received frame. If not 0, a frame was successfully received
 static uint16_t rxMultiplexDelay = 0; //simple delay for decoder multiplexer to avoid receiving the same frame twice
@@ -495,9 +495,7 @@ bool Ax25ReadNextRxFrame(uint8_t **dst, uint16_t *size, int8_t *peak, int8_t *va
 	*valley = rxFrame[rxFrameTail].valley;
 	*level = rxFrame[rxFrameTail].level;
 	*size = rxFrame[rxFrameTail].size;
-#ifdef ENABLE_FX25
 	*corrected = rxFrame[rxFrameTail].corrected;
-#endif
 
 	rxFrameBufferFull = false;
 
@@ -526,10 +524,6 @@ void Ax25BitParse(uint8_t bit, uint8_t modem)
 				frameReceived |= ((rxState[i].frameReceived > 0) << i);
 				rxState[i].frameReceived = 0;
 			}
-
-			rxFrameTail++;
-			rxFrameTail %= FRAME_MAX_COUNT;
-			rxFrameBufferFull = false;
 		}
 
 	}
@@ -652,19 +646,12 @@ void Ax25BitParse(uint8_t bit, uint8_t modem)
 	if((rx->rx != RX_STAGE_FX25_FRAME) && (rx->rx != RX_STAGE_FX25_TAG))
 	{
 #else
-<<<<<<< HEAD
-	{
-		//this condition must not be checked when FX.25 is enabled
-		//because FX.25 parity bytes and tags contain >= 7 consecutive ones
-		if((rx->rawData & 0x7F) == 0x7F) //received 7 consecutive ones, this is an error (sometimes called "escape byte")
-=======
 	{
 		//this condition must not be checked when FX.25 is enabled
 		//because FX.25 parity bytes and tags contain >= 7 consecutive ones
 		if((rx->rawData & 0x7F) == 0x7F) //received 7 consecutive ones, this is an error (sometimes called "escape byte")
 		{
 			rx->rx = RX_STAGE_FLAG;
-			ModemClearRMS(modem);
 			rx->receivedByte = 0;
 			rx->receivedBitIdx = 0;
 			rx->frameIdx = 0;
@@ -686,26 +673,21 @@ void Ax25BitParse(uint8_t bit, uint8_t modem)
 		if((rx->fx25Mode != NULL) && (rx->frameIdx == (rx->fx25Mode->K + rx->fx25Mode->T)))
 		{
 			uint8_t fixed = 0;
-			if(Fx25Decode(rx->frame, rx->fx25Mode, &fixed))
+			bool fecSuccess = Fx25Decode(rx->frame, rx->fx25Mode, &fixed);
+			uint16_t crc;
+			struct FrameHandle *h = parseFx25Frame(rx->frame, rx->frameIdx, &crc);
+			if(h != NULL)
 			{
-				uint16_t crc;
-				struct FrameHandle *h = parseFx25Frame(rx->frame, rx->frameIdx, &crc);
-				if(h != NULL)
+				rx->frameReceived = 1;
+				ModemGetSignalLevel(modem, &h->peak, &h->valley, &h->level);
+				if(fecSuccess)
 				{
-					rx->frameReceived = 1;
-					ModemGetSignalLevel(modem, &h->peak, &h->valley, &h->level);
 					h->corrected = fixed;
-					//FX.25 (RS) decoding is not reentrant/interrupt safe
-					//use only one modem when FX.25 is enabled
-					// if(crc != lastCrc)
-					// {
-//						h->signalLevel = ModemGetRMS(modem);
-						h->fx25Mode = rx->fx25Mode;
-						lastCrc = crc;
-					// }
-					// else
-					// 	removeLastFrameFromRxBuffer();
+					h->fx25Mode = rx->fx25Mode;
 				}
+				else
+					h->corrected = AX25_NOT_FX25;
+				lastCrc = crc;
 			}
 			rx->rx = RX_STAGE_FX25_TAG;
 			rx->tagBit = 0;
diff --git a/Src/config.c b/Src/config.c
index 96efb31..98c72cc 100644
--- a/Src/config.c
+++ b/Src/config.c
@@ -199,9 +199,9 @@ void ConfigWrite(void)
 {
 	ConfigErase();
 
-	writeString(CONFIG_CALL, GeneralConfig.call, sizeof(GeneralConfig.call));
+	writeString(CONFIG_CALL, GeneralConfig.call, 6);
 	write(CONFIG_SSID, GeneralConfig.callSsid);
-	writeString(CONFIG_DEST, GeneralConfig.dest, sizeof(GeneralConfig.dest));
+	writeString(CONFIG_DEST, GeneralConfig.dest, 6);
 	write(CONFIG_TXDELAY, Ax25Config.txDelayLength);
 	write(CONFIG_TXTAIL, Ax25Config.txTailLength);
 	write(CONFIG_TXQUIET, Ax25Config.quietTime);
@@ -283,10 +283,10 @@ uint8_t ConfigRead(void)
 	readString(CONFIG_CALL, GeneralConfig.call, sizeof(GeneralConfig.call));
 	GeneralConfig.callSsid = (uint8_t)read(CONFIG_SSID);
 	uint8_t temp[6];
-	readString(CONFIG_DEST, temp, sizeof(temp));
+	readString(CONFIG_DEST, temp, 6);
 	if((temp[0] >= ('A' << 1)) && (temp[0] <= ('Z' << 1)) && ((temp[0] & 1) == 0)) //check if stored destination address is correct (we just assume it by reading the first byte)
 	{
-		memcpy(GeneralConfig.dest, temp, sizeof(temp));
+		memcpy(GeneralConfig.dest, temp, 6);
 	}
 	Ax25Config.txDelayLength = read(CONFIG_TXDELAY);
 	Ax25Config.txTailLength = read(CONFIG_TXTAIL);
diff --git a/Src/digipeater.c b/Src/digipeater.c
index 78c925c..ba63fae 100644
--- a/Src/digipeater.c
+++ b/Src/digipeater.c
@@ -198,7 +198,7 @@ static void makeFrame(uint8_t *frame, uint16_t elStart, uint16_t len, uint32_t h
     }
     else //normal mode
     {
-    	if(sizeof(buf) < (len + 7))
+    	if((uint32_t)sizeof(buf) < (len + 7))
     		return;
     	buffer = buf;
     }
@@ -218,7 +218,7 @@ static void makeFrame(uint8_t *frame, uint16_t elStart, uint16_t len, uint32_t h
     	{
     		if(elStart != 14)
     			return; //this is not the very first path element, frame not received directly
-    		if((alias >= 0) && (alias <= 3) && (ssid != n))
+    		if((alias <= 3) && (ssid != n))
     			return; //n-N type alias, but n is not equal to N, frame not received directly
     	}
     }
diff --git a/Src/drivers/modem.c b/Src/drivers/modem.c
index 9272379..ebdd5b7 100644
--- a/Src/drivers/modem.c
+++ b/Src/drivers/modem.c
@@ -32,27 +32,23 @@ along with VP-Digi.  If not, see <http://www.gnu.org/licenses/>.
  * DCD_MAXPULSE and DCD_THRES difference sets the DCD "inertia" so that the DCD state won't change rapidly when a valid signal is present
  * DCD_DEC is the DCD pulse counter decrementation value when symbol changes too far from PLL counter zero
  * DCD_INC is the DCD pulse counter incrementation value when symbol changes near the PLL counter zero
- * DCD_PLLTUNE is the DCD timing coefficient when symbol changes, pll_counter = pll_counter * DCD_PLLTUNE
- * The DCD mechanism is described in afsk_demod().
+ * The DCD mechanism is described in demodulate().
  * All values were selected by trial and error
  */
 #define DCD1200_MAXPULSE 100
 #define DCD1200_THRES 30
-#define DCD1200_DEC 1
-#define DCD1200_INC 7
-#define DCD1200_PLLTUNE 0
+#define DCD1200_DEC 2
+#define DCD1200_INC 1
 
-#define DCD9600_MAXPULSE 200
-#define DCD9600_THRES 80
-#define DCD9600_DEC 3
-#define DCD9600_INC 6
-#define DCD9600_PLLTUNE 0
+#define DCD9600_MAXPULSE 70
+#define DCD9600_THRES 50
+#define DCD9600_DEC 5
+#define DCD9600_INC 1
 
-#define DCD300_MAXPULSE 50
-#define DCD300_THRES 6
-#define DCD300_DEC 1
+#define DCD300_MAXPULSE 140
+#define DCD300_THRES 120
+#define DCD300_DEC 3
 #define DCD300_INC 5
-#define DCD300_PLLTUNE 0
 
 #define N1200 8 //samples per symbol @ fs=9600, oversampling = 38400 Hz
 #define N9600 4 //fs=38400, oversampling = 153600 Hz
@@ -84,7 +80,7 @@ static enum ModemTxTestMode txTestState; //current TX test mode
 static uint8_t demodCount; //actual number of parallel demodulators
 static uint16_t dacSine[DAC_SINE_SIZE]; //sine samples for DAC
 static uint8_t dacSineIdx; //current sine sample index
-static uint16_t samples[4]; //very raw received samples, filled directly by DMA
+static volatile uint16_t samples[4]; //very raw received samples, filled directly by DMA
 static uint8_t currentSymbol; //current symbol for NRZI encoding
 static uint8_t scrambledSymbol; //current symbol after scrambling
 static float markFreq; //mark frequency
@@ -198,12 +194,11 @@ struct DemodState
 
 	int32_t dcdPll; //DCD PLL main counter
 	uint8_t dcdLastSymbol; //last symbol for DCD
-	uint8_t dcdCounter; //DCD "pulse" counter (incremented when RX signal is correct)
-	int32_t dcdMax;
-	int32_t dcdThres;
-	int32_t dcdInc;
-	int32_t dcdDec;
-	float dcdAdjust;
+	uint16_t dcdCounter; //DCD "pulse" counter (incremented when RX signal is correct)
+	uint16_t dcdMax;
+	uint16_t dcdThres;
+	uint16_t dcdInc;
+	uint16_t dcdDec;
 
 	int16_t peak;
 	int16_t valley;
@@ -314,7 +309,7 @@ void DMA1_Channel2_IRQHandler(void)
 	 	DMA1->IFCR |= DMA_IFCR_CTCIF2;
 
 		//each sample is 12 bits, output sample is 13 bits
-		int16_t sample = ((samples[0] + samples[1] + samples[2] + samples[3]) >> 1) - 4095; //calculate input sample (decimation)
+		int32_t sample = ((samples[0] + samples[1] + samples[2] + samples[3]) >> 1) - 4095; //calculate input sample (decimation)
 
 		bool partialDcd = false;
 
@@ -352,21 +347,17 @@ void DMA1_Channel2_IRQHandler(void)
  	if(ModemConfig.modem == MODEM_9600)
  	{
  		if(ModemConfig.usePWM)
- 			sample = scrambledSymbol ? 89 : 0;
+ 			sample = scrambledSymbol ? 99 : 0;
  		else
  			sample = scrambledSymbol ? 15 : 0;
 
  		sample = filter(&demodState[0].lpf, sample);
- 		if(sample < 0)
- 			sample = 0;
- 		else if(sample > 15)
- 			sample = 15;
  	}
  	else
  	{
  		sample = dacSine[dacSineIdx];
  		dacSineIdx++;
- 		dacSineIdx &= (DAC_SINE_SIZE - 1);
+ 		dacSineIdx %= DAC_SINE_SIZE;
  	}
 
  	if(ModemConfig.usePWM)
@@ -381,17 +372,6 @@ void DMA1_Channel2_IRQHandler(void)
 
 }
 
-void txBit()
-{
-	if(Ax25GetTxBit() == 0) //get next bit and check if it's 0
-	{
-		currentSymbol ^= 1; //change symbol - NRZI encoding
-	}
-	//if 1, no symbol change
-
-	scrambledSymbol = scramble(currentSymbol);
-}
-
 
 /**
  * @brief ISR for baudrate generator timer. NRZI encoding is done here.
@@ -411,17 +391,21 @@ void txBit()
  	}
  	else //transmit test mode
  	{
+ 		if(ModemConfig.modem == MODEM_9600)
+ 		{
+ 			scrambledSymbol ^= 1;
+ 			return;
+ 		}
  		currentSymbol ^= 1; //change symbol
  	}
 
- 	TIM1->CNT = 0;
-
  	if(ModemConfig.modem == MODEM_9600)
  	{
  		scrambledSymbol = scramble(currentSymbol);
  	}
  	else
  	{
+ 	 	TIM1->CNT = 0;
  		if(currentSymbol) //current symbol is space
  			TIM1->ARR = spaceStep;
  		else //mark
@@ -503,18 +487,19 @@ static int32_t demodulate(int16_t sample, struct DemodState *dem)
 	//when configured properly, it's generally immune to noise, as the detected tone changes much faster than 1200 baud
 	//it's also important to set some maximum value for DCD counter, otherwise the DCD is "sticky"
 
-	dem->dcdPll = (signed)((unsigned)(dem->dcdPll) + (unsigned)(dem->pllStep)); //keep PLL ticking at the frequency equal to baudrate
+
+	dem->dcdPll = (int32_t)((uint32_t)(dem->dcdPll) + (uint32_t)(dem->pllStep)); //keep PLL ticking at the frequency equal to baudrate
 
 	if((sample > 0) != dem->dcdLastSymbol) //tone changed
 	{
-		if(abs(dem->dcdPll) < dem->pllStep) //tone change occurred near zero
+		if(abs(dem->dcdPll) <= (uint32_t)(dem->pllStep)) //tone change occurred near zero
 			dem->dcdCounter += dem->dcdInc; //increase DCD counter
 		else //tone change occurred far from zero
 		{
 			if(dem->dcdCounter >= dem->dcdDec) //avoid overflow
 				dem->dcdCounter -= dem->dcdDec; //decrease DCD counter
 		}
-		dem->dcdPll = (int)(dem->dcdPll * dem->dcdAdjust); //adjust PLL
+		dem->dcdPll = 0;
 	}
 
 	dem->dcdLastSymbol = sample > 0; //store last symbol for symbol change detection
@@ -544,7 +529,7 @@ static void decode(uint8_t symbol, uint8_t demod)
 	//Current symbol is sampled at PLL counter overflow, so symbol transition should occur at PLL counter zero
 	int32_t previous = dem->pll; //store last clock state
 
-	dem->pll = (signed)((unsigned)(dem->pll) + (unsigned)(dem->pllStep)); //keep PLL running
+	dem->pll = (int32_t)((uint32_t)(dem->pll) + (uint32_t)(dem->pllStep)); //keep PLL running
 
 	dem->rawSymbols <<= 1; //store received unsynchronized symbol
 	dem->rawSymbols |= (symbol & 1);
@@ -606,6 +591,15 @@ void ModemTxTestStart(enum ModemTxTestMode type)
 	 NVIC_DisableIRQ(DMA1_Channel2_IRQn); //disable RX DMA interrupt
 	 NVIC_EnableIRQ(TIM1_UP_IRQn); //enable DAC interrupt
 
+	 if(ModemConfig.modem == MODEM_9600)
+	 {
+		TIM1->ARR = 103;
+		//enable baudrate generator
+		TIM3->CR1 = TIM_CR1_CEN; //enable timer
+		NVIC_EnableIRQ(TIM3_IRQn); //enable interrupt in NVIC
+		return;
+	 }
+
 	 if(type == TEST_MARK)
 	 {
 	 	TIM1->ARR = markStep;
@@ -642,6 +636,8 @@ void ModemTxTestStop(void)
 void ModemTransmitStart(void)
 {
 	 setPtt(1); //PTT on
+	 if(ModemConfig.modem == MODEM_9600)
+		 TIM1->ARR = 103;
 
 	 TIM3->CR1 = TIM_CR1_CEN;
 	 TIM1->CR1 = TIM_CR1_CEN;
@@ -813,7 +809,6 @@ void ModemInit(void)
 		demodState[0].dcdThres = DCD1200_THRES;
 		demodState[0].dcdInc = DCD1200_INC;
 		demodState[0].dcdDec = DCD1200_DEC;
-		demodState[0].dcdAdjust = DCD1200_PLLTUNE;
 
 		demodState[1].pllStep = PLL1200_STEP;
 		demodState[1].pllLockedAdjust = PLL1200_LOCKED_TUNE;
@@ -822,7 +817,6 @@ void ModemInit(void)
 		demodState[1].dcdThres = DCD1200_THRES;
 		demodState[1].dcdInc = DCD1200_INC;
 		demodState[1].dcdDec = DCD1200_DEC;
-		demodState[1].dcdAdjust = DCD1200_PLLTUNE;
 
 		demodState[1].prefilter = PREFILTER_NONE;
 		demodState[1].lpf.coeffs = (int16_t*)lpf1200;
@@ -895,7 +889,6 @@ void ModemInit(void)
 		demodState[0].dcdThres = DCD300_THRES;
 		demodState[0].dcdInc = DCD300_INC;
 		demodState[0].dcdDec = DCD300_DEC;
-		demodState[0].dcdAdjust = DCD300_PLLTUNE;
 
 		demodState[0].prefilter = PREFILTER_FLAT;
 		demodState[0].bpf.coeffs = (int16_t*)bpf300;
@@ -920,7 +913,6 @@ void ModemInit(void)
 		demodState[0].dcdThres = DCD9600_THRES;
 		demodState[0].dcdInc = DCD9600_INC;
 		demodState[0].dcdDec = DCD9600_DEC;
-		demodState[0].dcdAdjust = DCD9600_PLLTUNE;
 
 		demodState[0].prefilter = PREFILTER_NONE;
 		//this filter will be used for RX and TX
diff --git a/Src/fx25.c b/Src/fx25.c
index 9c84b2e..316ce3c 100644
--- a/Src/fx25.c
+++ b/Src/fx25.c
@@ -27,35 +27,24 @@ const struct Fx25Mode Fx25ModeList[11] =
 
 static inline uint8_t hammingDistance(uint64_t x, uint64_t y)
 {
+	x ^= y;
 	uint8_t distance = 0;
 	for(uint8_t i = 0; i < 64; i++)
 	{
-		distance += (x ^ y) & 1;
+		distance += (x & 1) > 0;
 		x >>= 1;
-		y >>= 1;
 	}
 	return distance;
 }
 
 const struct Fx25Mode* Fx25GetModeForTag(uint64_t tag)
 {
-	struct Fx25Mode *closest = NULL;
-	uint8_t closestDistance = 255;
 	for(uint8_t i = 0; i < sizeof(Fx25ModeList) / sizeof(*Fx25ModeList); i++)
 	{
-		uint8_t distance = hammingDistance(tag, Fx25ModeList[i].tag);
-		if(distance == 0)
+		if(hammingDistance(tag, Fx25ModeList[i].tag) <= FX25_MAX_DISTANCE)
 			return &Fx25ModeList[i];
-		else if(distance < closestDistance)
-		{
-			closest = (struct Fx25Mode*)&Fx25ModeList[i];
-			closestDistance = distance;
-		}
 	}
-	if(closestDistance <= FX25_MAX_DISTANCE)
-		return closest;
-	else
-		return NULL;
+	return NULL;
 }
 
 const struct Fx25Mode* Fx25GetModeForSize(uint16_t size)
diff --git a/Src/main.c b/Src/main.c
index 696fc89..6e4b512 100644
--- a/Src/main.c
+++ b/Src/main.c
@@ -136,7 +136,7 @@ static void handleFrame(void)
 							TermSendToAll(MODE_MONITOR, (uint8_t*)"F", 1);
 							break;
 						case PREFILTER_NONE:
-							TermSendToAll(MODE_MONITOR, (uint8_t*)"|", 1);
+							TermSendToAll(MODE_MONITOR, (uint8_t*)"*", 1);
 					}
 				}
 				else
diff --git a/Src/terminal.c b/Src/terminal.c
index a25ecc4..bb373a3 100644
--- a/Src/terminal.c
+++ b/Src/terminal.c
@@ -392,8 +392,8 @@ void TermParse(Uart *src)
 	{
 		UartSendString(src, (uint8_t*)"Switched to configuration mode\r\n"
 				"Some settings require the device to be rebooted\r\n"
-				"in order to behave correctly"
-				"Always use \"save\" to save and reboot", 0);
+				"in order to behave correctly\r\n"
+				"Always use \"save\" to save and reboot\r\n", 0);
 		src->mode = MODE_TERM;
 		return;
 	}
@@ -602,10 +602,10 @@ void TermParse(Uart *src)
 	 */
 	else if(!strncmp(cmd, "modem", 5))
 	{
-		if(!strncmp(&cmd[6], "1200", 4))
-			ModemConfig.modem = MODEM_1200;
-		else if(!strncmp(&cmd[6], "1200_V23", 8))
+		if(!strncmp(&cmd[6], "1200_V23", 8))
 			ModemConfig.modem = MODEM_1200_V23;
+		else if(!strncmp(&cmd[6], "1200", 4))
+			ModemConfig.modem = MODEM_1200;
 		else if(!strncmp(&cmd[6], "300", 3))
 			ModemConfig.modem = MODEM_300;
 		else if(!strncmp(&cmd[6], "9600", 4))