diff --git a/src/modules/SX1276.cpp b/src/modules/SX1276.cpp
index 496e32fc..eb7da074 100644
--- a/src/modules/SX1276.cpp
+++ b/src/modules/SX1276.cpp
@@ -57,20 +57,20 @@ int16_t SX1276::setFrequency(float freq) {
     return(ERR_INVALID_FREQUENCY);
   }
   
-  // sensitivity optimization for 500kHz bandwidth
-  // see SX1276/77/78 Errata, section 2.1 for details
-  if(abs(_bw - 500.0) <= 0.001) {
-    if((freq >= 862.0) && (freq <= 1020.0)) {
-      _mod->SPIwriteRegister(0x36, 0x02);
-      _mod->SPIwriteRegister(0x3a, 0x64);
-    } else if((freq >= 410.0) && (freq <= 525.0)) {
-      _mod->SPIwriteRegister(0x36, 0x03);
-      _mod->SPIwriteRegister(0x3a, 0x65);
-    }
-  }
-  
   // SX1276/77/78 Errata fixes
   if(getActiveModem() == SX127X_LORA) {
+    // sensitivity optimization for 500kHz bandwidth
+    // see SX1276/77/78 Errata, section 2.1 for details
+    if(abs(_bw - 500.0) <= 0.001) {
+      if((freq >= 862.0) && (freq <= 1020.0)) {
+        _mod->SPIwriteRegister(0x36, 0x02);
+        _mod->SPIwriteRegister(0x3a, 0x64);
+      } else if((freq >= 410.0) && (freq <= 525.0)) {
+        _mod->SPIwriteRegister(0x36, 0x02);
+        _mod->SPIwriteRegister(0x3a, 0x7F);
+      }
+    }
+  
     // mitigation of receiver spurious response
     // see SX1276/77/78 Errata, section 2.3 for details
     if(abs(_bw - 7.8) <= 0.001) {
diff --git a/src/modules/SX1277.cpp b/src/modules/SX1277.cpp
index 6eeac497..406bf2c6 100644
--- a/src/modules/SX1277.cpp
+++ b/src/modules/SX1277.cpp
@@ -66,8 +66,8 @@ int16_t SX1277::setFrequency(float freq) {
         _mod->SPIwriteRegister(0x36, 0x02);
         _mod->SPIwriteRegister(0x3a, 0x64);
       } else if((freq >= 410.0) && (freq <= 525.0)) {
-        _mod->SPIwriteRegister(0x36, 0x03);
-        _mod->SPIwriteRegister(0x3a, 0x65);
+        _mod->SPIwriteRegister(0x36, 0x02);
+        _mod->SPIwriteRegister(0x3a, 0x7F);
       }
     }
     
diff --git a/src/modules/SX1278.cpp b/src/modules/SX1278.cpp
index 2615a015..2341c054 100644
--- a/src/modules/SX1278.cpp
+++ b/src/modules/SX1278.cpp
@@ -93,8 +93,8 @@ int16_t SX1278::setFrequency(float freq) {
         _mod->SPIwriteRegister(0x36, 0x02);
         _mod->SPIwriteRegister(0x3a, 0x64);
       } else if((freq >= 410.0) && (freq <= 525.0)) {
-        _mod->SPIwriteRegister(0x36, 0x03);
-        _mod->SPIwriteRegister(0x3a, 0x65);
+        _mod->SPIwriteRegister(0x36, 0x02);
+        _mod->SPIwriteRegister(0x3a, 0x7F);
       }
     }
     
@@ -168,7 +168,7 @@ int16_t SX1278::setBandwidth(float bw) {
     newBandwidth = SX1278_BW_15_60_KHZ;
   } else if(abs(bw - 20.8) <= 0.001) {
     newBandwidth = SX1278_BW_20_80_KHZ;
-  } else if(abs(bw - 32.5) <= 0.001) {
+  } else if(abs(bw - 31.25) <= 0.001) {
     newBandwidth = SX1278_BW_31_25_KHZ;
   } else if(abs(bw - 41.7) <= 0.001) {
     newBandwidth = SX1278_BW_41_70_KHZ;
diff --git a/src/modules/SX127x.cpp b/src/modules/SX127x.cpp
index 3a8795b5..4906e220 100644
--- a/src/modules/SX127x.cpp
+++ b/src/modules/SX127x.cpp
@@ -106,11 +106,11 @@ int16_t SX127x::beginFSK(uint8_t chipVersion, float br, float freqDev, float rxB
 }
 
 int16_t SX127x::transmit(String& str, uint8_t addr) {
-  return(SX127x::transmit(str.c_str()), addr);
+  return(SX127x::transmit(str.c_str(), addr));
 }
 
 int16_t SX127x::transmit(const char* str, uint8_t addr) {
-  return(SX127x::transmit((uint8_t*)str, strlen(str)), addr);
+  return(SX127x::transmit((uint8_t*)str, strlen(str), addr));
 }
 
 int16_t SX127x::transmit(uint8_t* data, size_t len, uint8_t addr) {
@@ -207,7 +207,7 @@ int16_t SX127x::transmit(uint8_t* data, size_t len, uint8_t addr) {
       return(state);
     }
     
-    // wait for transmission end or timeout (150 % of expected time-one-air)
+    // wait for transmission end or timeout (150 % of expected time-on-air)
     uint32_t timeout = (uint32_t)((((float)(len * 8)) / (_br * 1000.0)) * 1500.0);
     uint32_t start = millis();
     while(!digitalRead(_mod->int0())) {
@@ -241,11 +241,11 @@ int16_t SX127x::receive(String& str, size_t len) {
 }
 
 int16_t SX127x::receive(uint8_t* data, size_t len) {
+  // set mode to standby
+  int16_t state = setMode(SX127X_STANDBY);
+
   int16_t modem = getActiveModem();
   if(modem == SX127X_LORA) {
-    // set mode to standby
-    int16_t state = setMode(SX127X_STANDBY);
-    
     // set DIO pin mapping
     state |= _mod->SPIsetRegValue(SX127X_REG_DIO_MAPPING_1, SX127X_DIO0_RX_DONE | SX127X_DIO1_RX_TIMEOUT, 7, 4);
     
@@ -263,7 +263,6 @@ int16_t SX127x::receive(uint8_t* data, size_t len) {
     }
     
     // wait for packet reception or timeout
-    uint32_t start = millis();
     while(!digitalRead(_mod->int0())) {
       if(digitalRead(_mod->int1())) {
         clearIRQFlags();
@@ -307,11 +306,8 @@ int16_t SX127x::receive(uint8_t* data, size_t len) {
     return(ERR_NONE);
     
   } else if(modem == SX127X_FSK_OOK) {
-    // set mode to standby
-    int16_t state = setMode(SX127X_STANDBY);
-    
     // set DIO pin mapping
-    state |= _mod->SPIsetRegValue(SX127X_REG_DIO_MAPPING_1, SX127X_DIO0_PACK_PACKET_SENT, 7, 6);
+    state |= _mod->SPIsetRegValue(SX127X_REG_DIO_MAPPING_1, SX127X_DIO0_PACK_PAYLOAD_READY, 7, 6);
     
     // clear interrupt flags
     clearIRQFlags();
@@ -460,21 +456,35 @@ int16_t SX127x::startReceive() {
   // set mode to standby
   int16_t state = setMode(SX127X_STANDBY);
   
-  // set DIO pin mapping
-  state |= _mod->SPIsetRegValue(SX127X_REG_DIO_MAPPING_1, SX127X_DIO0_RX_DONE | SX127X_DIO1_RX_TIMEOUT, 7, 4);
-  
-  // clear interrupt flags
-  clearIRQFlags();
-  
-  // set FIFO pointers
-  state |= _mod->SPIsetRegValue(SX127X_REG_FIFO_RX_BASE_ADDR, SX127X_FIFO_RX_BASE_ADDR_MAX);
-  state |= _mod->SPIsetRegValue(SX127X_REG_FIFO_ADDR_PTR, SX127X_FIFO_RX_BASE_ADDR_MAX);
-  if(state != ERR_NONE) {
-    return(state);
+  if(modem == SX127X_LORA) {
+    // set DIO pin mapping
+    state |= _mod->SPIsetRegValue(SX127X_REG_DIO_MAPPING_1, SX127X_DIO0_RX_DONE | SX127X_DIO1_RX_TIMEOUT, 7, 4);
+    
+    // clear interrupt flags
+    clearIRQFlags();
+    
+    // set FIFO pointers
+    state |= _mod->SPIsetRegValue(SX127X_REG_FIFO_RX_BASE_ADDR, SX127X_FIFO_RX_BASE_ADDR_MAX);
+    state |= _mod->SPIsetRegValue(SX127X_REG_FIFO_ADDR_PTR, SX127X_FIFO_RX_BASE_ADDR_MAX);
+    if(state != ERR_NONE) {
+      return(state);
+    }
+    
+    // set mode to continuous reception
+    return(setMode(SX127X_RXCONTINUOUS));
+    
+  } else if(modem == SX127X_FSK_OOK) {
+    // set DIO pin mapping
+    state |= _mod->SPIsetRegValue(SX127X_REG_DIO_MAPPING_1, SX127X_DIO0_PACK_PAYLOAD_READY, 7, 6);
+    
+    // clear interrupt flags
+    clearIRQFlags();
+    
+    // set mode to receive
+    return(setMode(SX127X_RX));
   }
   
-  // set mode to continuous reception
-  return(setMode(SX127X_RXCONTINUOUS));
+  return(ERR_UNKNOWN);
 }
 
 void SX127x::setDio0Action(void (*func)(void)) {
@@ -486,11 +496,11 @@ void SX127x::setDio1Action(void (*func)(void)) {
 }
 
 int16_t SX127x::startTransmit(String& str, uint8_t addr) {
-  return(SX127x::startTransmit(str.c_str()), addr);
+  return(SX127x::startTransmit(str.c_str(), addr));
 }
 
 int16_t SX127x::startTransmit(const char* str, uint8_t addr) {
-  return(SX127x::startTransmit((uint8_t*)str, strlen(str)), addr);
+  return(SX127x::startTransmit((uint8_t*)str, strlen(str), addr));
 }
 
 int16_t SX127x::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
@@ -701,11 +711,11 @@ int16_t SX127x::setPreambleLength(uint16_t preambleLength) {
   return(state);
 }
 
-float SX127x::getFrequencyError() {
+float SX127x::getFrequencyError(bool autoCorrect) {
   int16_t modem = getActiveModem();
   if(modem == SX127X_LORA) {
     // get raw frequency error
-    uint32_t raw = _mod->SPIgetRegValue(SX127X_REG_FEI_MSB, 3, 0) << 16;
+    uint32_t raw = (uint32_t)_mod->SPIgetRegValue(SX127X_REG_FEI_MSB, 3, 0) << 16;
     raw |= _mod->SPIgetRegValue(SX127X_REG_FEI_MID) << 8;
     raw |= _mod->SPIgetRegValue(SX127X_REG_FEI_LSB);
     
@@ -715,12 +725,19 @@ float SX127x::getFrequencyError() {
     // check the first bit
     if(raw & 0x80000) {
       // frequency error is negative
+      raw |= (uint32_t)0xFFF00000;
       raw = ~raw + 1;
       error = (((float)raw * (float)base)/32000000.0) * (_bw/500.0) * -1.0;
     } else {
       error = (((float)raw * (float)base)/32000000.0) * (_bw/500.0);
     }
     
+    if(autoCorrect) {
+      // adjust LoRa modem data rate
+      float ppmOffset = 0.95 * (error/32.0);
+      _mod->SPIwriteRegister(0x27, (uint8_t)ppmOffset);
+    }
+    
     return(error);
     
   } else if(modem == SX127X_FSK_OOK) {
@@ -734,6 +751,7 @@ float SX127x::getFrequencyError() {
     // check the first bit
     if(raw & 0x8000) {
       // frequency error is negative
+      raw |= (uint32_t)0xFFF00000;
       raw = ~raw + 1;
       error = (float)raw * (32000000.0 / (float)(base << 19)) * -1.0;
     } else {
@@ -902,7 +920,7 @@ int16_t SX127x::setSyncWord(uint8_t* syncWord, size_t len) {
   }
 
   // check constraints
-  if(len >= 7) {
+  if(len > 8) {
     return(ERR_INVALID_SYNC_WORD);
   }
   
diff --git a/src/modules/SX127x.h b/src/modules/SX127x.h
index 622da902..f18d41bd 100644
--- a/src/modules/SX127x.h
+++ b/src/modules/SX127x.h
@@ -318,7 +318,7 @@
 #define SX127X_PREAMBLE_DETECTOR_ON                   0b10000000  //  7     7     preamble detection enabled (default)
 #define SX127X_PREAMBLE_DETECTOR_1_BYTE               0b00000000  //  6     5     preamble detection size: 1 byte (default)
 #define SX127X_PREAMBLE_DETECTOR_2_BYTE               0b00100000  //  6     5                              2 bytes
-#define SX127X_PREAMBLE_DETECTOR_2_BYTE               0b01000000  //  6     5                              3 bytes
+#define SX127X_PREAMBLE_DETECTOR_3_BYTE               0b01000000  //  6     5                              3 bytes
 #define SX127X_PREAMBLE_DETECTOR_TOL                  0x0A        //  4     0     default number of tolerated errors per chip (4 chips per bit)
 
 // SX127X_REG_RX_TIMEOUT_1
@@ -555,7 +555,7 @@ class SX127x: public PhysicalLayer {
     int16_t setSyncWord(uint8_t syncWord);
     int16_t setCurrentLimit(uint8_t currentLimit);
     int16_t setPreambleLength(uint16_t preambleLength);
-    float getFrequencyError();
+    float getFrequencyError(bool autoCorrect = false);
     int16_t setBitRate(float br);
     int16_t setFrequencyDeviation(float freqDev);
     int16_t setRxBandwidth(float rxBw);