diff --git a/Src/main.c b/Src/main.c
index 7cc74df..ffb9c7e 100644
--- a/Src/main.c
+++ b/Src/main.c
@@ -53,6 +53,7 @@
 
 /* USER CODE BEGIN Includes */
 #include "LEDIndicator.h"
+#include "Log.h"
 #include <stdint.h>
 /* USER CODE END Includes */
 
@@ -398,15 +399,18 @@ void SystemClock_Config(void)
 
     /**Initializes the CPU, AHB and APB busses clocks 
     */
-  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSE|RCC_OSCILLATORTYPE_MSI;
+  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSE
+                              |RCC_OSCILLATORTYPE_MSI|RCC_OSCILLATORTYPE_HSI;
   RCC_OscInitStruct.LSEState = RCC_LSE_ON;
   RCC_OscInitStruct.MSIState = RCC_MSI_ON;
+  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
+  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
   RCC_OscInitStruct.MSICalibrationValue = RCC_MSICALIBRATION_DEFAULT;
-  RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_8;
+  RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_11;
   RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
   RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_MSI;
-  RCC_OscInitStruct.PLL.PLLM = 1;
-  RCC_OscInitStruct.PLL.PLLN = 10;
+  RCC_OscInitStruct.PLL.PLLM = 4;
+  RCC_OscInitStruct.PLL.PLLN = 8;
   RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV7;
   RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV2;
   RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;
@@ -432,16 +436,16 @@ void SystemClock_Config(void)
   PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC|RCC_PERIPHCLK_USART2
                               |RCC_PERIPHCLK_I2C3|RCC_PERIPHCLK_RNG
                               |RCC_PERIPHCLK_ADC;
-  PeriphClkInit.Usart2ClockSelection = RCC_USART2CLKSOURCE_PCLK1;
-  PeriphClkInit.I2c3ClockSelection = RCC_I2C3CLKSOURCE_PCLK1;
+  PeriphClkInit.Usart2ClockSelection = RCC_USART2CLKSOURCE_HSI;
+  PeriphClkInit.I2c3ClockSelection = RCC_I2C3CLKSOURCE_HSI;
   PeriphClkInit.AdcClockSelection = RCC_ADCCLKSOURCE_PLLSAI1;
   PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
   PeriphClkInit.RngClockSelection = RCC_RNGCLKSOURCE_PLLSAI1;
   PeriphClkInit.PLLSAI1.PLLSAI1Source = RCC_PLLSOURCE_MSI;
-  PeriphClkInit.PLLSAI1.PLLSAI1M = 1;
-  PeriphClkInit.PLLSAI1.PLLSAI1N = 12;
+  PeriphClkInit.PLLSAI1.PLLSAI1M = 4;
+  PeriphClkInit.PLLSAI1.PLLSAI1N = 24;
   PeriphClkInit.PLLSAI1.PLLSAI1P = RCC_PLLP_DIV7;
-  PeriphClkInit.PLLSAI1.PLLSAI1Q = RCC_PLLQ_DIV4;
+  PeriphClkInit.PLLSAI1.PLLSAI1Q = RCC_PLLQ_DIV6;
   PeriphClkInit.PLLSAI1.PLLSAI1R = RCC_PLLR_DIV4;
   PeriphClkInit.PLLSAI1.PLLSAI1ClockOut = RCC_PLLSAI1_48M2CLK|RCC_PLLSAI1_ADC1CLK;
   if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
@@ -596,7 +600,7 @@ static void MX_I2C3_Init(void)
 {
 
   hi2c3.Instance = I2C3;
-  hi2c3.Init.Timing = 0x00702991;
+  hi2c3.Init.Timing = 0x00000107;
   hi2c3.Init.OwnAddress1 = 0;
   hi2c3.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
   hi2c3.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
@@ -980,10 +984,242 @@ static void MX_GPIO_Init(void)
 
 /* USER CODE BEGIN 4 */
 
-// These are no-ops on NucleoTNC. Always running at 80MHz.
-void SysClock80() {}
-void SysClock48() {}
-void SysClock4() {}
+
+void SysClock48()
+{
+    RCC_OscInitTypeDef RCC_OscInitStruct;
+    RCC_ClkInitTypeDef RCC_ClkInitStruct;
+    RCC_PeriphCLKInitTypeDef PeriphClkInit;
+
+    if (HAL_RCC_GetHCLKFreq() == 48000000) return;
+
+    INFO("Setting 48MHz SysClock.");
+
+    taskENTER_CRITICAL();
+
+    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_SYSCLK;
+    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
+
+    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
+    {
+      _Error_Handler(__FILE__, __LINE__);
+    }
+
+    /**Configure the Systick interrupt time
+    */
+    HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
+
+    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSI;
+    RCC_OscInitStruct.MSIState = RCC_MSI_ON;
+    RCC_OscInitStruct.MSICalibrationValue = RCC_MSICALIBRATION_DEFAULT;
+    RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_11;
+    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
+    RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_MSI;
+    RCC_OscInitStruct.PLL.PLLM = 3;
+    RCC_OscInitStruct.PLL.PLLN = 12;
+    RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV7;
+    RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV4;
+    RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV4;
+    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
+    {
+      _Error_Handler(__FILE__, __LINE__);
+    }
+
+    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_SYSCLK;
+    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_MSI;
+
+    PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC|RCC_PERIPHCLK_USART2
+                                |RCC_PERIPHCLK_I2C3|RCC_PERIPHCLK_RNG
+                                |RCC_PERIPHCLK_ADC;
+    PeriphClkInit.Usart2ClockSelection = RCC_USART2CLKSOURCE_HSI;
+    PeriphClkInit.I2c3ClockSelection = RCC_I2C3CLKSOURCE_HSI;
+    PeriphClkInit.AdcClockSelection = RCC_ADCCLKSOURCE_PLLSAI1;
+    PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
+    PeriphClkInit.RngClockSelection = RCC_RNGCLKSOURCE_PLLSAI1;
+    PeriphClkInit.PLLSAI1.PLLSAI1Source = RCC_PLLSOURCE_MSI;
+    PeriphClkInit.PLLSAI1.PLLSAI1M = 4;
+    PeriphClkInit.PLLSAI1.PLLSAI1N = 24;
+    PeriphClkInit.PLLSAI1.PLLSAI1P = RCC_PLLP_DIV7;
+    PeriphClkInit.PLLSAI1.PLLSAI1Q = RCC_PLLQ_DIV6;
+    PeriphClkInit.PLLSAI1.PLLSAI1R = RCC_PLLR_DIV4;
+    PeriphClkInit.PLLSAI1.PLLSAI1ClockOut = RCC_PLLSAI1_48M2CLK|RCC_PLLSAI1_ADC1CLK;
+    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
+    {
+      _Error_Handler(__FILE__, __LINE__);
+    }
+
+    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
+    {
+      _Error_Handler(__FILE__, __LINE__);
+    }
+
+    /**Configure the Systick interrupt time
+    */
+    HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
+    taskEXIT_CRITICAL();
+}
+
+void SysClock72()
+{
+    RCC_OscInitTypeDef RCC_OscInitStruct;
+    RCC_ClkInitTypeDef RCC_ClkInitStruct;
+    RCC_PeriphCLKInitTypeDef PeriphClkInit;
+
+    if (HAL_RCC_GetHCLKFreq() == 72000000) return;
+
+    INFO("Setting 72MHz SysClock.");
+
+    taskENTER_CRITICAL();
+
+    HAL_RCCEx_DisableMSIPLLMode();
+
+    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_SYSCLK;
+    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
+
+    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
+    {
+      _Error_Handler(__FILE__, __LINE__);
+    }
+
+    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSI;
+    RCC_OscInitStruct.MSIState = RCC_MSI_ON;
+    RCC_OscInitStruct.MSICalibrationValue = RCC_MSICALIBRATION_DEFAULT;
+    RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_11;
+    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
+    RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_MSI;
+    RCC_OscInitStruct.PLL.PLLM = 4;
+    RCC_OscInitStruct.PLL.PLLN = 12;
+    RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV7;
+    RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV2;
+    RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;
+    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
+    {
+      _Error_Handler(__FILE__, __LINE__);
+    }
+
+    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_SYSCLK;
+    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
+
+    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_4) != HAL_OK)
+    {
+      _Error_Handler(__FILE__, __LINE__);
+    }
+
+    PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC|RCC_PERIPHCLK_USART2
+                                |RCC_PERIPHCLK_I2C3|RCC_PERIPHCLK_RNG
+                                |RCC_PERIPHCLK_ADC;
+    PeriphClkInit.Usart2ClockSelection = RCC_USART2CLKSOURCE_HSI;
+    PeriphClkInit.I2c3ClockSelection = RCC_I2C3CLKSOURCE_HSI;
+    PeriphClkInit.AdcClockSelection = RCC_ADCCLKSOURCE_PLLSAI1;
+    PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
+    PeriphClkInit.RngClockSelection = RCC_RNGCLKSOURCE_PLLSAI1;
+    PeriphClkInit.PLLSAI1.PLLSAI1Source = RCC_PLLSOURCE_MSI;
+    PeriphClkInit.PLLSAI1.PLLSAI1M = 4;
+    PeriphClkInit.PLLSAI1.PLLSAI1N = 24;
+    PeriphClkInit.PLLSAI1.PLLSAI1P = RCC_PLLP_DIV7;
+    PeriphClkInit.PLLSAI1.PLLSAI1Q = RCC_PLLQ_DIV6;
+    PeriphClkInit.PLLSAI1.PLLSAI1R = RCC_PLLR_DIV4;
+    PeriphClkInit.PLLSAI1.PLLSAI1ClockOut = RCC_PLLSAI1_48M2CLK|RCC_PLLSAI1_ADC1CLK;
+    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
+    {
+      _Error_Handler(__FILE__, __LINE__);
+    }
+
+    HAL_RCCEx_EnableMSIPLLMode();
+
+    /**Configure the Systick interrupt time
+    */
+    HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
+    taskEXIT_CRITICAL();
+}
+
+void SysClock80()
+{
+    RCC_OscInitTypeDef RCC_OscInitStruct;
+    RCC_ClkInitTypeDef RCC_ClkInitStruct;
+    RCC_PeriphCLKInitTypeDef PeriphClkInit;
+
+    if (HAL_RCC_GetHCLKFreq() == 80000000) return;
+
+    INFO("Setting 80MHz SysClock.");
+
+    taskENTER_CRITICAL();
+
+    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_SYSCLK;
+    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
+
+    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
+    {
+      _Error_Handler(__FILE__, __LINE__);
+    }
+
+    RCC_OscInitStruct.OscillatorType = 0;
+    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
+    RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_MSI;
+    RCC_OscInitStruct.PLL.PLLM = 3;
+    RCC_OscInitStruct.PLL.PLLN = 20;
+    RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV7;
+    RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV4;
+    RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV4;
+    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
+    {
+      _Error_Handler(__FILE__, __LINE__);
+    }
+
+    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_SYSCLK;
+    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
+
+    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_4) != HAL_OK)
+    {
+      _Error_Handler(__FILE__, __LINE__);
+    }
+
+    PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC|RCC_PERIPHCLK_USART2
+                                |RCC_PERIPHCLK_I2C3|RCC_PERIPHCLK_RNG
+                                |RCC_PERIPHCLK_ADC;
+    PeriphClkInit.Usart2ClockSelection = RCC_USART2CLKSOURCE_HSI;
+    PeriphClkInit.I2c3ClockSelection = RCC_I2C3CLKSOURCE_HSI;
+    PeriphClkInit.AdcClockSelection = RCC_ADCCLKSOURCE_PLLSAI1;
+    PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
+    PeriphClkInit.RngClockSelection = RCC_RNGCLKSOURCE_PLLSAI1;
+    PeriphClkInit.PLLSAI1.PLLSAI1Source = RCC_PLLSOURCE_MSI;
+    PeriphClkInit.PLLSAI1.PLLSAI1M = 3;
+    PeriphClkInit.PLLSAI1.PLLSAI1N = 18;
+    PeriphClkInit.PLLSAI1.PLLSAI1P = RCC_PLLP_DIV7;
+    PeriphClkInit.PLLSAI1.PLLSAI1Q = RCC_PLLQ_DIV6;
+    PeriphClkInit.PLLSAI1.PLLSAI1R = RCC_PLLR_DIV4;
+    PeriphClkInit.PLLSAI1.PLLSAI1ClockOut = RCC_PLLSAI1_48M2CLK|RCC_PLLSAI1_ADC1CLK;
+    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
+    {
+      _Error_Handler(__FILE__, __LINE__);
+    }
+
+    /**Configure the Systick interrupt time
+    */
+    HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
+    taskEXIT_CRITICAL();
+}
+
+void SysClock4()
+{
+    RCC_ClkInitTypeDef RCC_ClkInitStruct;
+
+    taskENTER_CRITICAL();
+
+    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_SYSCLK;
+    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_MSI;
+
+    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
+    {
+      _Error_Handler(__FILE__, __LINE__);
+    }
+
+    /**Configure the Systick interrupt time
+    */
+    HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
+
+    taskEXIT_CRITICAL();
+}
 
 /* USER CODE END 4 */
 
diff --git a/TNC/Afsk1200Demodulator.hpp b/TNC/Afsk1200Demodulator.hpp
index cf00443..30c601f 100644
--- a/TNC/Afsk1200Demodulator.hpp
+++ b/TNC/Afsk1200Demodulator.hpp
@@ -90,16 +90,12 @@ struct Afsk1200Demodulator : IDemodulator
         sConfig.Channel = AUDIO_IN;
         sConfig.Rank = ADC_REGULAR_RANK_1;
         sConfig.SingleDiff = ADC_SINGLE_ENDED;
-        sConfig.SamplingTime = ADC_SAMPLETIME_12CYCLES_5;
+        sConfig.SamplingTime = ADC_SAMPLETIME_24CYCLES_5;
         sConfig.OffsetNumber = ADC_OFFSET_NONE;
         sConfig.Offset = 0;
         if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
             CxxErrorHandler();
-#ifndef NUCLEOTNC
         startADC(1817, ADC_BLOCK_SIZE);
-#else
-        startADC(3029, ADC_BLOCK_SIZE);
-#endif
     }
 
     void stop() override
diff --git a/TNC/Fsk9600Demodulator.hpp b/TNC/Fsk9600Demodulator.hpp
index 3e914c2..80e694d 100644
--- a/TNC/Fsk9600Demodulator.hpp
+++ b/TNC/Fsk9600Demodulator.hpp
@@ -54,7 +54,7 @@ struct Fsk9600Demodulator : IDemodulator
 
     void start() override
     {
-        SysClock80();
+        SysClock72();
 
         auto const& bpf_coeffs = bpf_bank[kiss::settings().rx_twist + 3];
         const q15_t* bpf = bpf_coeffs.data();
@@ -78,7 +78,7 @@ struct Fsk9600Demodulator : IDemodulator
         if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
             CxxErrorHandler();
 
-        startADC(416, ADC_BLOCK_SIZE);
+        startADC(374, ADC_BLOCK_SIZE);
     }
 
     void stop() override
diff --git a/TNC/Fsk9600Modulator.cpp b/TNC/Fsk9600Modulator.cpp
index 2f2d7b7..8f4c3b9 100644
--- a/TNC/Fsk9600Modulator.cpp
+++ b/TNC/Fsk9600Modulator.cpp
@@ -36,10 +36,10 @@ void Fsk9600Modulator::init(const kiss::Hardware& hw)
     state = State::STOPPED;
     level = Level::HIGH;
 
-    SysClock80();
+    SysClock72();
 
     // Configure 80MHz clock for 192ksps.
-    htim7.Init.Period = 416;
+    htim7.Init.Period = 374;
     if (HAL_TIM_Base_Init(&htim7) != HAL_OK)
     {
         ERROR("htim7 init failed");