diff --git a/src/codecs/horus/horus_packet_v2.c b/src/codecs/horus/horus_packet_v2.c
index 842b6a2..9e05fcb 100644
--- a/src/codecs/horus/horus_packet_v2.c
+++ b/src/codecs/horus/horus_packet_v2.c
@@ -44,14 +44,27 @@ size_t horus_packet_v2_create(uint8_t *payload, size_t length, telemetry_data *d
         horus_packet.Sats += 200;
     }
 
+    uint8_t *custom_data_pointer = horus_packet.CustomData;
+
+    uint16_t cus_packet_counter = horus_v2_packet_counter;
+    memcpy(custom_data_pointer, &cus_packet_counter, sizeof(cus_packet_counter));
+    custom_data_pointer += sizeof(cus_packet_counter);
+
+    int16_t cus_temp_celsius_10 = (int16_t) (data->internal_temperature_celsius_100 / 10.0f);
+    memcpy(custom_data_pointer, &cus_temp_celsius_10, sizeof(cus_temp_celsius_10));
+    custom_data_pointer += sizeof(cus_temp_celsius_10);
+
     int16_t ext_temp_celsius_10 = (int16_t) (data->temperature_celsius_100 / 10.0f);
-    memcpy(horus_packet.CustomData, &ext_temp_celsius_10, sizeof(ext_temp_celsius_10));
+    memcpy(custom_data_pointer, &ext_temp_celsius_10, sizeof(ext_temp_celsius_10));
+    custom_data_pointer += sizeof(ext_temp_celsius_10);
 
     uint8_t ext_humidity_percentage = (uint8_t) (data->humidity_percentage_100 / 100.0f);
-    memcpy(horus_packet.CustomData + sizeof(ext_temp_celsius_10), &ext_humidity_percentage, sizeof(ext_humidity_percentage));
+    memcpy(custom_data_pointer, &ext_humidity_percentage, sizeof(ext_humidity_percentage));
+    custom_data_pointer += sizeof(ext_humidity_percentage);
 
     uint16_t ext_pressure_mbar = (uint8_t) (data->pressure_mbar_100 / 100.0f);
-    memcpy(horus_packet.CustomData + sizeof(ext_temp_celsius_10) + sizeof(ext_humidity_percentage), &ext_pressure_mbar, sizeof(ext_pressure_mbar));
+    memcpy(custom_data_pointer, &ext_pressure_mbar, sizeof(ext_pressure_mbar));
+    // custom_data_pointer += sizeof(ext_pressure_mbar);
 
     horus_packet.Checksum = (uint16_t) calculate_crc16_checksum((char *) &horus_packet, sizeof(horus_packet) - 2);
 
diff --git a/src/config.h b/src/config.h
index 22f049e..6e8165b 100644
--- a/src/config.h
+++ b/src/config.h
@@ -30,8 +30,8 @@
 // Number of character pairs to include in locator
 #define LOCATOR_PAIR_COUNT_FULL 6 // max. 6 (12 characters WWL)
 
-// Delay after transmission for modes that do not use time synchronization
-#define RADIO_POST_TRANSMIT_DELAY_MS 1000
+// Delay after transmission for modes that do not use time synchronization. Zero delay allows continuous transmit mode for Horus V1 and V2.
+#define RADIO_POST_TRANSMIT_DELAY_MS 0
 
 // Threshold for time-synchronized modes regarding how far from scheduled transmission time the transmission is still allowed
 #define RADIO_TIME_SYNC_THRESHOLD_MS 2000
@@ -50,8 +50,12 @@
 #define RADIO_SI4032_TX_HORUS_V1 true
 #define RADIO_SI4032_TX_HORUS_V2 true
 
+// Continuous transmit mode can be enabled for *either* Horus V1 or V2, but not both. This disables all other transmission modes.
+#define RADIO_SI4032_TX_HORUS_V1_CONTINUOUS false
+#define RADIO_SI4032_TX_HORUS_V2_CONTINUOUS false
+
 // Transmit frequencies for the Si4032 transmitter modes
-#define RADIO_SI4032_TX_FREQUENCY_CW   432500000
+#define RADIO_SI4032_TX_FREQUENCY_CW        432500000
 #define RADIO_SI4032_TX_FREQUENCY_APRS_1200 432500000
 // Use a frequency offset to place FSK tones slightly above the defined frequency for SSB reception
 #define RADIO_SI4032_TX_FREQUENCY_HORUS_V1  432501000
@@ -125,6 +129,12 @@
 // Delay transmission for an N second offset after the scheduled time.
 #define APRS_TIME_SYNC_OFFSET_SECONDS 0
 
+/**
+ * Common Horus 4FSK mode settings
+ */
+
+#define HORUS_FREQUENCY_OFFSET_SI4032 0
+
 /**
  * Horus V1 4FSK mode settings
  */
@@ -134,8 +144,8 @@
 #define HORUS_V1_BAUD_RATE_SI4032 100
 #define HORUS_V1_BAUD_RATE_SI5351 50
 #define HORUS_V1_PREAMBLE_LENGTH 16
-#define HORUS_V1_FREQUENCY_OFFSET_SI4032 0
-#define HORUS_V1_TONE_SPACING_HZ 270
+#define HORUS_V1_IDLE_PREAMBLE_LENGTH 32
+#define HORUS_V1_TONE_SPACING_HZ_SI5351 270
 
 // Schedule transmission every N seconds, counting from beginning of an hour (based on GPS time). Set to zero to disable time sync.
 #define HORUS_V1_TIME_SYNC_SECONDS 0
@@ -151,8 +161,8 @@
 #define HORUS_V2_BAUD_RATE_SI4032 100
 #define HORUS_V2_BAUD_RATE_SI5351 50
 #define HORUS_V2_PREAMBLE_LENGTH 16
-#define HORUS_V2_FREQUENCY_OFFSET_SI4032 0
-#define HORUS_V2_TONE_SPACING_HZ 270
+#define HORUS_V2_IDLE_PREAMBLE_LENGTH 32
+#define HORUS_V2_TONE_SPACING_HZ_SI5351 270
 
 // Schedule transmission every N seconds, counting from beginning of an hour (based on GPS time). Set to zero to disable time sync.
 #define HORUS_V2_TIME_SYNC_SECONDS 0
diff --git a/src/hal/i2c.c b/src/hal/i2c.c
index 5f68f44..dc3a4da 100644
--- a/src/hal/i2c.c
+++ b/src/hal/i2c.c
@@ -5,6 +5,7 @@
 #include "hal.h"
 #include "i2c.h"
 #include "delay.h"
+#include "log.h"
 
 struct _i2c_port {
     I2C_TypeDef *i2c;
@@ -59,6 +60,9 @@ void i2c_init()
     while (I2C_GetFlagStatus(I2C_PORT, I2C_FLAG_BUSY) && count--) {
         delay_ms(1);
     }
+    if (count == 0) {
+        log_error("ERROR: I²C bus busy during initialization");
+    }
 
     I2C_Cmd(I2C_PORT, ENABLE);
 }
@@ -70,38 +74,110 @@ void i2c_uninit()
     RCC_APB1PeriphClockCmd(I2C_PORT_RCC_PERIPH, DISABLE);
 }
 
+static void i2c_reset_bus(i2c_port *port)
+{
+    for (int i = 0; i < 10; i++) {
+        I2C_GenerateSTOP(port->i2c, ENABLE);
+        delay_us(100);
+        I2C_GenerateSTOP(port->i2c, DISABLE);
+        delay_us(100);
+    }
+
+    I2C_GetFlagStatus(port->i2c, I2C_FLAG_BUSY);
+    I2C_GetFlagStatus(port->i2c, I2C_FLAG_BERR);
+    I2C_GetFlagStatus(port->i2c, I2C_FLAG_SMBALERT);
+    I2C_GetFlagStatus(port->i2c, I2C_FLAG_TIMEOUT);
+    I2C_GetFlagStatus(port->i2c, I2C_FLAG_PECERR);
+    I2C_GetFlagStatus(port->i2c, I2C_FLAG_OVR);
+    I2C_GetFlagStatus(port->i2c, I2C_FLAG_AF);
+    I2C_GetFlagStatus(port->i2c, I2C_FLAG_ARLO);
+    I2C_GetFlagStatus(port->i2c, I2C_FLAG_BERR);
+    I2C_ClearFlag(port->i2c, I2C_FLAG_SMBALERT | I2C_FLAG_TIMEOUT | I2C_FLAG_PECERR | I2C_FLAG_OVR | I2C_FLAG_AF | I2C_FLAG_ARLO | I2C_FLAG_BERR);
+}
+
+static int i2c_wait_until_not_busy(i2c_port *port)
+{
+    __IO uint32_t timeout = 0xFFFFFF;
+
+    while (I2C_GetFlagStatus(I2C_PORT, I2C_FLAG_BUSY)) {
+        if (--timeout == 0) {
+            log_error("ERROR: Timeout - I2C bus busy");
+            i2c_reset_bus(port);
+            return HAL_ERROR_TIMEOUT;
+        }
+    }
+
+    return HAL_OK;
+}
+
+static bool i2c_wait_event(i2c_port *port, uint32_t flag)
+{
+    __IO uint32_t timeout = 0xFFFFFF;
+
+    while (I2C_CheckEvent(port->i2c, flag) != SUCCESS) {
+        if (--timeout == 0) {
+            log_error("ERROR: WE event timeout: 0x%08lx", flag);
+            i2c_reset_bus(port);
+            return false;
+        }
+    }
+
+    return true;
+}
+
 static int i2c_prepare_op(i2c_port *port, uint8_t address)
 {
     I2C_AcknowledgeConfig(port->i2c, ENABLE);
     I2C_GenerateSTART(port->i2c, ENABLE);
 
-    while (!I2C_CheckEvent(port->i2c, I2C_EVENT_MASTER_MODE_SELECT));
+    if (!i2c_wait_event(port, I2C_EVENT_MASTER_MODE_SELECT)) {
+        log_error("ERROR: PO MMS timeout: 0x%02x", address);
+        return HAL_ERROR_TIMEOUT;
+    }
     I2C_Send7bitAddress(port->i2c, address, I2C_Direction_Transmitter);
 
-    while (!I2C_CheckEvent(port->i2c, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));
+    if (!i2c_wait_event(port, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED)) {
+        log_error("ERROR: PO MTMS timeout: 0x%02x", address);
+        return HAL_ERROR_TIMEOUT;
+    }
 
     return HAL_OK;
 }
 
 static int i2c_prepare_op_with_register(i2c_port *port, uint8_t address, uint8_t reg)
 {
-    i2c_prepare_op(port, address);
+    int result = i2c_prepare_op(port, address);
+    if (result != HAL_OK) {
+        return result;
+    }
 
     I2C_SendData(port->i2c, reg);
-    while (!I2C_CheckEvent(port->i2c, I2C_EVENT_MASTER_BYTE_TRANSMITTED));
+    if (!i2c_wait_event(port, I2C_EVENT_MASTER_BYTE_TRANSMITTED)) {
+        log_error("ERROR: POWR MBT timeout: 0x%02x 0x%02x", address, reg);
+        return HAL_ERROR_TIMEOUT;
+    }
 
     return HAL_OK;
 }
 
 static int i2c_prepare_read(i2c_port *port, uint8_t address, uint8_t reg)
 {
-    i2c_prepare_op_with_register(port, address, reg);
+    int result = i2c_prepare_op_with_register(port, address, reg);
+    if (result != HAL_OK) {
+        return result;
+    }
 
     I2C_GenerateSTART(port->i2c, ENABLE);
-    while (!I2C_CheckEvent(port->i2c, I2C_EVENT_MASTER_MODE_SELECT));
+    if (!i2c_wait_event(port, I2C_EVENT_MASTER_MODE_SELECT)) {
+        log_error("ERROR: PR MMS timeout: 0x%02x 0x%02x", address, reg);
+        return HAL_ERROR_TIMEOUT;
+    }
 
     I2C_Send7bitAddress(port->i2c, address, I2C_Direction_Receiver);
-    while (!I2C_CheckEvent(port->i2c, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED));
+    if (!i2c_wait_event(port, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED)) {
+        log_error("ERROR: PR MRMS timeout: 0x%02x 0x%02x", address, reg);
+        return HAL_ERROR_TIMEOUT;
+    }
 
     return HAL_OK;
 }
@@ -111,7 +187,10 @@ static int i2c_finish_read(i2c_port *port)
     I2C_GenerateSTOP(port->i2c, ENABLE);
     I2C_AcknowledgeConfig(port->i2c, DISABLE);
 
-    while (!I2C_CheckEvent(port->i2c, I2C_EVENT_MASTER_BYTE_RECEIVED));
+    if (!i2c_wait_event(port, I2C_EVENT_MASTER_BYTE_RECEIVED)) {
+        log_error("ERROR: FR MBR timeout");
+        return HAL_ERROR_TIMEOUT;
+    }
     I2C_ReceiveData(port->i2c);
 
     return HAL_OK;
@@ -126,17 +205,31 @@ static int i2c_finish_write(i2c_port *port)
 {
     I2C_GenerateSTOP(port->i2c, ENABLE);
 
-    while (!I2C_CheckEvent(port->i2c, I2C_EVENT_MASTER_BYTE_TRANSMITTED));
+    if (!i2c_wait_event(port, I2C_EVENT_MASTER_BYTE_TRANSMITTED)) {
+        log_error("ERROR: FW MBT timeout");
+        return HAL_ERROR_TIMEOUT;
+    }
 
     return HAL_OK;
 }
 
 int i2c_read_bytes(i2c_port *port, uint8_t address, uint8_t reg, uint8_t size, uint8_t *data)
 {
-    i2c_prepare_read(port, address, reg);
+    int result = i2c_wait_until_not_busy(port);
+    if (result != HAL_OK) {
+        return result;
+    }
+
+    result = i2c_prepare_read(port, address, reg);
+    if (result != HAL_OK) {
+        return result;
+    }
 
     for (uint8_t i = 0; i < size; i++) {
-        while (!I2C_CheckEvent(port->i2c, I2C_EVENT_MASTER_BYTE_RECEIVED));
+        if (!i2c_wait_event(port, I2C_EVENT_MASTER_BYTE_RECEIVED)) {
+            log_error("ERROR: MBR timeout: 0x%02x 0x%02x", address, reg);
+            return HAL_ERROR_TIMEOUT;
+        }
         data[i] = I2C_ReceiveData(port->i2c);
     }
 
@@ -152,11 +245,22 @@ int i2c_read_byte(i2c_port *port, uint8_t address, uint8_t reg, uint8_t *data)
 
 int i2c_write_bytes(i2c_port *port, uint8_t address, uint8_t reg, uint8_t size, uint8_t *data)
 {
-    i2c_prepare_write(port, address, reg);
+    int result = i2c_wait_until_not_busy(port);
+    if (result != HAL_OK) {
+        return result;
+    }
+
+    result = i2c_prepare_write(port, address, reg);
+    if (result != HAL_OK) {
+        return result;
+    }
 
     for (uint8_t i = 0; i < size; i++) {
         I2C_SendData(port->i2c, data[i]);
-        while (!I2C_CheckEvent(port->i2c, I2C_EVENT_MASTER_BYTE_TRANSMITTED));
+        if (!i2c_wait_event(port, I2C_EVENT_MASTER_BYTE_TRANSMITTED)) {
+            log_error("ERROR: MBF timeout: 0x%02x 0x%02x", address, reg);
+            return HAL_ERROR_TIMEOUT;
+        }
     }
 
     i2c_finish_write(port);
diff --git a/src/radio.c b/src/radio.c
index add3ef8..8b3629e 100644
--- a/src/radio.c
+++ b/src/radio.c
@@ -23,6 +23,58 @@
 #include "radio_payload_fsq.h"
 
 radio_transmit_entry radio_transmit_schedule[] = {
+#if RADIO_SI4032_TX_HORUS_V1_CONTINUOUS == true
+        {
+                .enabled = RADIO_SI4032_TX_HORUS_V1,
+                .radio_type = RADIO_TYPE_SI4032,
+                .data_mode = RADIO_DATA_MODE_HORUS_V1,
+                .time_sync_seconds = HORUS_V1_TIME_SYNC_SECONDS,
+                .time_sync_seconds_offset = HORUS_V1_TIME_SYNC_OFFSET_SECONDS,
+                .frequency = RADIO_SI4032_TX_FREQUENCY_HORUS_V1,
+                .tx_power = RADIO_SI4032_TX_POWER,
+                .symbol_rate = HORUS_V1_BAUD_RATE_SI4032,
+                .payload_encoder = &radio_horus_v1_payload_encoder,
+                .fsk_encoder_api = &mfsk_fsk_encoder_api,
+        },
+        {
+                .enabled = RADIO_SI4032_TX_HORUS_V1,
+                .radio_type = RADIO_TYPE_SI4032,
+                .data_mode = RADIO_DATA_MODE_HORUS_V1,
+                .time_sync_seconds = HORUS_V1_TIME_SYNC_SECONDS,
+                .time_sync_seconds_offset = HORUS_V1_TIME_SYNC_OFFSET_SECONDS,
+                .frequency = RADIO_SI4032_TX_FREQUENCY_HORUS_V1,
+                .tx_power = RADIO_SI4032_TX_POWER,
+                .symbol_rate = HORUS_V1_BAUD_RATE_SI4032,
+                .payload_encoder = &radio_horus_v1_idle_encoder,
+                .fsk_encoder_api = &mfsk_fsk_encoder_api,
+        },
+#elif RADIO_SI4032_TX_HORUS_V2_CONTINUOUS == true
+        {
+                .enabled = RADIO_SI4032_TX_HORUS_V2,
+                .radio_type = RADIO_TYPE_SI4032,
+                .data_mode = RADIO_DATA_MODE_HORUS_V2,
+                .time_sync_seconds = HORUS_V2_TIME_SYNC_SECONDS,
+                .time_sync_seconds_offset = HORUS_V2_TIME_SYNC_OFFSET_SECONDS,
+                .frequency = RADIO_SI4032_TX_FREQUENCY_HORUS_V2,
+                .tx_power = RADIO_SI4032_TX_POWER,
+                .symbol_rate = HORUS_V2_BAUD_RATE_SI4032,
+                .payload_encoder = &radio_horus_v2_payload_encoder,
+                .fsk_encoder_api = &mfsk_fsk_encoder_api,
+        },
+        {
+                .enabled = RADIO_SI4032_TX_HORUS_V2,
+                .radio_type = RADIO_TYPE_SI4032,
+                .data_mode = RADIO_DATA_MODE_HORUS_V2,
+                .time_sync_seconds = HORUS_V2_TIME_SYNC_SECONDS,
+                .time_sync_seconds_offset = HORUS_V2_TIME_SYNC_OFFSET_SECONDS,
+                .frequency = RADIO_SI4032_TX_FREQUENCY_HORUS_V2,
+                .tx_power = RADIO_SI4032_TX_POWER,
+                .symbol_rate = HORUS_V2_BAUD_RATE_SI4032,
+                .payload_encoder = &radio_horus_v2_idle_encoder,
+                .fsk_encoder_api = &mfsk_fsk_encoder_api,
+        },
+#else
+#endif
         {
                 .enabled = RADIO_SI4032_TX_CW,
                 .radio_type = RADIO_TYPE_SI4032,
@@ -71,6 +123,8 @@ radio_transmit_entry radio_transmit_schedule[] = {
                 .payload_encoder = &radio_horus_v2_payload_encoder,
                 .fsk_encoder_api = &mfsk_fsk_encoder_api,
         },
+#if RADIO_SI5351_ENABLE == true
+#if RADIO_SI5351_TX_CW == true
         {
                 .enabled = RADIO_SI5351_TX_CW,
                 .radio_type = RADIO_TYPE_SI5351,
@@ -83,6 +137,8 @@ radio_transmit_entry radio_transmit_schedule[] = {
                 .payload_encoder = &radio_cw_payload_encoder,
                 .fsk_encoder_api = &morse_fsk_encoder_api,
         },
+#endif
+#if RADIO_SI5351_TX_HORUS_V1 == true
         {
                 .enabled = RADIO_SI5351_TX_HORUS_V1,
                 .radio_type = RADIO_TYPE_SI5351,
@@ -95,6 +151,8 @@ radio_transmit_entry radio_transmit_schedule[] = {
                 .payload_encoder = &radio_horus_v1_payload_encoder,
                 .fsk_encoder_api = &mfsk_fsk_encoder_api,
         },
+#endif
+#if RADIO_SI5351_TX_HORUS_V2 == true
         {
                 .enabled = RADIO_SI5351_TX_HORUS_V2,
                 .radio_type = RADIO_TYPE_SI5351,
@@ -107,7 +165,8 @@ radio_transmit_entry radio_transmit_schedule[] = {
                 .payload_encoder = &radio_horus_v2_payload_encoder,
                 .fsk_encoder_api = &mfsk_fsk_encoder_api,
         },
-/*
+#endif
+#if RADIO_SI5351_TX_WSPR == true
         {
                 .enabled = RADIO_SI5351_TX_WSPR,
                 .radio_type = RADIO_TYPE_SI5351,
@@ -119,6 +178,8 @@ radio_transmit_entry radio_transmit_schedule[] = {
                 .payload_encoder = &radio_wspr_payload_encoder,
                 .fsk_encoder_api = &jtencode_fsk_encoder_api,
         },
+#endif
+#if RADIO_SI5351_TX_FT8 == true
         {
                 .enabled = RADIO_SI5351_TX_FT8,
                 .radio_type = RADIO_TYPE_SI5351,
@@ -130,6 +191,8 @@ radio_transmit_entry radio_transmit_schedule[] = {
                 .payload_encoder = &radio_ft8_payload_encoder,
                 .fsk_encoder_api = &jtencode_fsk_encoder_api,
         },
+#endif
+#if RADIO_SI5351_TX_JT9 == true
         {
                 .enabled = RADIO_SI5351_TX_JT9,
                 .radio_type = RADIO_TYPE_SI5351,
@@ -141,6 +204,8 @@ radio_transmit_entry radio_transmit_schedule[] = {
                 .payload_encoder = &radio_jt9_payload_encoder,
                 .fsk_encoder_api = &jtencode_fsk_encoder_api,
         },
+#endif
+#if RADIO_SI5351_TX_JT4 == true
         {
                 .enabled = RADIO_SI5351_TX_JT4,
                 .radio_type = RADIO_TYPE_SI5351,
@@ -152,6 +217,8 @@ radio_transmit_entry radio_transmit_schedule[] = {
                 .payload_encoder = &radio_jt4_payload_encoder,
                 .fsk_encoder_api = &jtencode_fsk_encoder_api,
         },
+#endif
+#if RADIO_SI5351_TX_JT65 == true
         {
                 .enabled = RADIO_SI5351_TX_JT65,
                 .radio_type = RADIO_TYPE_SI5351,
@@ -163,7 +230,8 @@ radio_transmit_entry radio_transmit_schedule[] = {
                 .payload_encoder = &radio_jt65_payload_encoder,
                 .fsk_encoder_api = &jtencode_fsk_encoder_api,
         },
-*/
+#endif
+#if RADIO_SI5351_TX_FSQ == true
         {
                 .enabled = RADIO_SI5351_TX_FSQ,
                 .radio_type = RADIO_TYPE_SI5351,
@@ -175,6 +243,8 @@ radio_transmit_entry radio_transmit_schedule[] = {
                 .payload_encoder = &radio_fsq_payload_encoder,
                 .fsk_encoder_api = &jtencode_fsk_encoder_api,
         },
+#endif
+#endif
         {
                 .end = true,
         }
@@ -315,7 +385,7 @@ static bool radio_start_transmit(radio_transmit_entry *entry)
             entry->fsk_encoder_api->set_data(&entry->fsk_encoder, radio_current_payload_length, radio_current_payload);
             break;
         case RADIO_DATA_MODE_HORUS_V1:
-            mfsk_encoder_new(&entry->fsk_encoder, MFSK_4, entry->symbol_rate, HORUS_V1_TONE_SPACING_HZ * 100);
+            mfsk_encoder_new(&entry->fsk_encoder, MFSK_4, entry->symbol_rate, HORUS_V1_TONE_SPACING_HZ_SI5351 * 100);
             radio_shared_state.radio_current_symbol_rate = entry->fsk_encoder_api->get_symbol_rate(&entry->fsk_encoder);
             entry->fsk_encoder_api->get_tones(&entry->fsk_encoder, &radio_shared_state.radio_current_fsk_tone_count,
                     &radio_shared_state.radio_current_fsk_tones);
@@ -324,7 +394,7 @@ static bool radio_start_transmit(radio_transmit_entry *entry)
             entry->fsk_encoder_api->set_data(&entry->fsk_encoder, radio_current_payload_length, radio_current_payload);
             break;
         case RADIO_DATA_MODE_HORUS_V2:
-            mfsk_encoder_new(&entry->fsk_encoder, MFSK_4, entry->symbol_rate, HORUS_V2_TONE_SPACING_HZ * 100);
+            mfsk_encoder_new(&entry->fsk_encoder, MFSK_4, entry->symbol_rate, HORUS_V2_TONE_SPACING_HZ_SI5351 * 100);
             radio_shared_state.radio_current_symbol_rate = entry->fsk_encoder_api->get_symbol_rate(&entry->fsk_encoder);
             entry->fsk_encoder_api->get_tones(&entry->fsk_encoder, &radio_shared_state.radio_current_fsk_tone_count,
                     &radio_shared_state.radio_current_fsk_tones);
diff --git a/src/radio_payload_horus_v1.c b/src/radio_payload_horus_v1.c
index a2261c0..f637864 100644
--- a/src/radio_payload_horus_v1.c
+++ b/src/radio_payload_horus_v1.c
@@ -6,7 +6,11 @@
 #include "telemetry.h"
 #include "radio_payload_horus_v1.h"
 
+#ifdef SEMIHOSTING_ENABLE
 #include "log.h"
+#endif
+
+#define HORUS_V1_PREAMBLE_BYTE 0x1B
 
 uint16_t radio_horus_v1_encode(uint8_t *payload, uint16_t length, telemetry_data *telemetry_data, char *message)
 {
@@ -23,7 +27,7 @@ uint16_t radio_horus_v1_encode(uint8_t *payload, uint16_t length, telemetry_data
 
     // Preamble to help the decoder lock-on after a quiet period.
     for (int i = 0; i < HORUS_V1_PREAMBLE_LENGTH; i++) {
-        payload[i] = 0x1b;
+        payload[i] = HORUS_V1_PREAMBLE_BYTE;
     }
 
     // Encode the packet, and write into the mfsk buffer.
@@ -34,6 +38,20 @@ uint16_t radio_horus_v1_encode(uint8_t *payload, uint16_t length, telemetry_data
     return encoded_length + HORUS_V1_PREAMBLE_LENGTH;
 }
 
+uint16_t radio_horus_v1_idle_encode(uint8_t *payload, uint16_t length, telemetry_data *telemetry_data, char *message)
+{
+    // Use the preamble for idle tones during continuous transmit mode
+    for (int i = 0; i < HORUS_V1_IDLE_PREAMBLE_LENGTH; i++) {
+        payload[i] = HORUS_V1_PREAMBLE_BYTE;
+    }
+
+    return HORUS_V1_IDLE_PREAMBLE_LENGTH;
+}
+
 payload_encoder radio_horus_v1_payload_encoder = {
         .encode = radio_horus_v1_encode,
 };
+
+payload_encoder radio_horus_v1_idle_encoder = {
+        .encode = radio_horus_v1_idle_encode,
+};
diff --git a/src/radio_payload_horus_v1.h b/src/radio_payload_horus_v1.h
index 0ac589e..29b1169 100644
--- a/src/radio_payload_horus_v1.h
+++ b/src/radio_payload_horus_v1.h
@@ -4,5 +4,6 @@
 #include "payload.h"
 
 extern payload_encoder radio_horus_v1_payload_encoder;
+extern payload_encoder radio_horus_v1_idle_encoder;
 
 #endif
diff --git a/src/radio_payload_horus_v2.c b/src/radio_payload_horus_v2.c
index a1a2888..549bca7 100644
--- a/src/radio_payload_horus_v2.c
+++ b/src/radio_payload_horus_v2.c
@@ -6,7 +6,11 @@
 #include "telemetry.h"
 #include "radio_payload_horus_v2.h"
 
+#ifdef SEMIHOSTING_ENABLE
 #include "log.h"
+#endif
+
+#define HORUS_V2_PREAMBLE_BYTE 0xE4
 
 uint16_t radio_horus_v2_encode(uint8_t *payload, uint16_t length, telemetry_data *telemetry_data, char *message)
 {
@@ -23,7 +27,7 @@ uint16_t radio_horus_v2_encode(uint8_t *payload, uint16_t length, telemetry_data
 
     // Preamble to help the decoder lock-on after a quiet period.
     for (int i = 0; i < HORUS_V2_PREAMBLE_LENGTH; i++) {
-        payload[i] = 0x1b;
+        payload[i] = HORUS_V2_PREAMBLE_BYTE;
     }
 
     // Encode the packet, and write into the mfsk buffer.
@@ -34,6 +38,20 @@ uint16_t radio_horus_v2_encode(uint8_t *payload, uint16_t length, telemetry_data
     return encoded_length + HORUS_V2_PREAMBLE_LENGTH;
 }
 
+uint16_t radio_horus_v2_idle_encode(uint8_t *payload, uint16_t length, telemetry_data *telemetry_data, char *message)
+{
+    // Use the preamble for idle tones during continuous transmit mode
+    for (int i = 0; i < HORUS_V2_IDLE_PREAMBLE_LENGTH; i++) {
+        payload[i] = HORUS_V2_PREAMBLE_BYTE;
+    }
+
+    return HORUS_V2_IDLE_PREAMBLE_LENGTH;
+}
+
 payload_encoder radio_horus_v2_payload_encoder = {
         .encode = radio_horus_v2_encode,
 };
+
+payload_encoder radio_horus_v2_idle_encoder = {
+        .encode = radio_horus_v2_idle_encode,
+};
diff --git a/src/radio_payload_horus_v2.h b/src/radio_payload_horus_v2.h
index 3087fd5..aff5828 100644
--- a/src/radio_payload_horus_v2.h
+++ b/src/radio_payload_horus_v2.h
@@ -4,5 +4,6 @@
 #include "payload.h"
 
 extern payload_encoder radio_horus_v2_payload_encoder;
+extern payload_encoder radio_horus_v2_idle_encoder;
 
 #endif
diff --git a/src/radio_si4032.c b/src/radio_si4032.c
index 4d7d765..b50e531 100644
--- a/src/radio_si4032.c
+++ b/src/radio_si4032.c
@@ -68,7 +68,7 @@ bool radio_start_transmit_si4032(radio_transmit_entry *entry, radio_module_state
         case RADIO_DATA_MODE_HORUS_V1:
         case RADIO_DATA_MODE_HORUS_V2: {
             fsk_tone *idle_tone = mfsk_get_idle_tone(&entry->fsk_encoder);
-            frequency_offset = (uint16_t) idle_tone->index + HORUS_V1_FREQUENCY_OFFSET_SI4032;
+            frequency_offset = (uint16_t) idle_tone->index + HORUS_FREQUENCY_OFFSET_SI4032;
             modulation_type = SI4032_MODULATION_TYPE_OOK;
             use_direct_mode = false;
 
@@ -258,7 +258,7 @@ inline void radio_handle_data_timer_si4032()
                 break;
             }
 
-            si4032_set_frequency_offset_small(tone_index + HORUS_V1_FREQUENCY_OFFSET_SI4032);
+            si4032_set_frequency_offset_small(tone_index + HORUS_FREQUENCY_OFFSET_SI4032);
 
             radio_shared_state.radio_symbol_count_interrupt++;
             break;