diff --git a/flight/Modules/GPS/GPS.c b/flight/Modules/GPS/GPS.c
index 353debebe..856e2db80 100644
--- a/flight/Modules/GPS/GPS.c
+++ b/flight/Modules/GPS/GPS.c
@@ -49,14 +49,6 @@
 #include "WorldMagModel.h"
 #include "CoordinateConversions.h"
 
-//#define FULL_COLD_RESTART				// uncomment this to tell the GPS to do a FULL COLD restart
-//#define DISABLE_GPS_TRESHOLD			//
-
-// ****************
-// constants/macros/typdefs
-
-#define GPS_TIMEOUT_MS 500
-
 // ****************
 // Private functions
 
@@ -66,17 +58,20 @@ static void setHomeLocation(GPSPositionData * gpsData);
 // ****************
 // Private constants
 
+//#define FULL_COLD_RESTART             // uncomment this to tell the GPS to do a FULL COLD restart
+//#define DISABLE_GPS_TRESHOLD          //
+
+#define GPS_TIMEOUT_MS                  500
+#define GPS_COMMAND_RESEND_TIMEOUT_MS   2000
+
 // Unfortunately need a good size stack for the WMM calculation
 #ifdef ENABLE_GPS_BINARY_GTOP
-	#define STACK_SIZE_BYTES 800
+	#define STACK_SIZE_BYTES            800
 #else
-	#define STACK_SIZE_BYTES 800
+	#define STACK_SIZE_BYTES            800
 #endif
 
-#define TASK_PRIORITY (tskIDLE_PRIORITY + 1)
-
-// ****************
-// Private types
+#define TASK_PRIORITY                   (tskIDLE_PRIORITY + 1)
 
 // ****************
 // Private variables
@@ -271,14 +266,17 @@ static void gpsTask(void *parameters)
 		// Check for GPS timeout
 		timeNowMs = xTaskGetTickCount() * portTICK_RATE_MS;
 		if ((timeNowMs - timeOfLastUpdateMs) > GPS_TIMEOUT_MS)
-		{
+		{	// we have not received any valid GPS sentences for a while.
+			// either the GPS is not plugged in or a hardware problem or the GPS has locked up.
+
 			GPSPositionGet(&GpsData);
 			GpsData.Status = GPSPOSITION_STATUS_NOGPS;
 			GPSPositionSet(&GpsData);
 			AlarmsSet(SYSTEMALARMS_ALARM_GPS, SYSTEMALARMS_ALARM_ERROR);
 
-			if ((timeNowMs - timeOfLastCommandMs) > 5000)	/// 5000ms
-			{	// resend the command .. just case the gps has only just been plugged in or the gps did not get our last command
+			if ((timeNowMs - timeOfLastCommandMs) >= GPS_COMMAND_RESEND_TIMEOUT_MS)
+			{	// resend the command .. just incase the gps has only just been plugged in or the gps did not get our last command
+				timeOfLastCommandMs = timeNowMs;
 
 				#ifdef ENABLE_GPS_BINARY_GTOP
 					GTOP_BIN_init();
@@ -299,13 +297,11 @@ static void gpsTask(void *parameters)
 				#ifdef DISABLE_GPS_TRESHOLD
 					PIOS_COM_SendStringNonBlocking(gpsPort,"$PMTK397,0*23\r\n");
 				#endif
-
-				timeOfLastCommandMs = timeNowMs;
 			}
 		}
 		else
-		{
-			// Had an update
+		{	// we appear to be receiving GPS sentences OK, we've had an update
+
 			HomeLocationData home;
 			HomeLocationGet(&home);
 
diff --git a/flight/Modules/GPS/GTOP_BIN.c b/flight/Modules/GPS/GTOP_BIN.c
index cd24b98a0..86f0ee57c 100644
--- a/flight/Modules/GPS/GTOP_BIN.c
+++ b/flight/Modules/GPS/GTOP_BIN.c
@@ -34,7 +34,6 @@
 #include "gpsposition.h"
 #include "gpstime.h"
 
-//#include <stdbool.h>
 #include <string.h>	// memmove
 
 #ifdef ENABLE_GPS_BINARY_GTOP
@@ -84,9 +83,10 @@ typedef struct
 
 // ************
 
-// buffer that holds the binary packet
+// buffer that holds the incoming binary packet
 static uint8_t gps_rx_buffer[sizeof(t_gps_bin_packet)] __attribute__ ((aligned(4)));
 
+// number of bytes currently in the binary packet buffer
 static uint8_t gps_rx_buffer_wr = 0;
 
 // ************
@@ -137,9 +137,8 @@ int GTOP_BIN_update_position(uint8_t b, volatile uint32_t *chksum_errors, volati
 			if (rx_packet->header == 0x2404)
 				break;	// found a valid header marker
 
-			// remove oldest byte from buffer
-			if (gps_rx_buffer_wr > 1)
-				memmove(gps_rx_buffer, gps_rx_buffer + 1, gps_rx_buffer_wr - 1);
+			// shift all the bytes down one position
+			memmove(gps_rx_buffer, gps_rx_buffer + 1, gps_rx_buffer_wr - 1);
 			gps_rx_buffer_wr--;
 		}
 
@@ -150,6 +149,7 @@ int GTOP_BIN_update_position(uint8_t b, volatile uint32_t *chksum_errors, volati
 
 		// we have enough bytes for a complete binary packet
 
+		// check to see if certain params are valid
 		if (rx_packet->header != 0x2404 ||
 			rx_packet->end_word != 0x0A0D ||
 			rx_packet->asterisk != 0x2A ||
@@ -159,6 +159,7 @@ int GTOP_BIN_update_position(uint8_t b, volatile uint32_t *chksum_errors, volati
 			(rx_packet->data.fix_type < 1 || rx_packet->data.fix_type > 3) )
 		{	// invalid packet
 			if (parsing_errors) *parsing_errors++;
+			// shift all the bytes down one position
 			memmove(gps_rx_buffer, gps_rx_buffer + 1, gps_rx_buffer_wr - 1);
 			gps_rx_buffer_wr--;
 			continue;
@@ -173,14 +174,13 @@ int GTOP_BIN_update_position(uint8_t b, volatile uint32_t *chksum_errors, volati
 			if (checksum != rx_packet->checksum)
 			{	// checksum error
 				if (chksum_errors) *chksum_errors++;
+				// shift all the bytes down one position
 				memmove(gps_rx_buffer, gps_rx_buffer + 1, gps_rx_buffer_wr - 1);
 				gps_rx_buffer_wr--;
 				continue;
 			}
 		}
 
-		// checksum appears correct
-		//
 		// we now have a valid complete binary packet, update the GpsData and GpsTime objects
 
 		// correct the endian order of the parameters
@@ -237,10 +237,10 @@ int GTOP_BIN_update_position(uint8_t b, volatile uint32_t *chksum_errors, volati
 		else
 			gps_rx_buffer_wr = 0;
 
-		return 0;	// found a valid packet
+		return 0;  // found a valid packet
 	}
 
-	return -1;	// no valid packet found
+	return -1;     // no valid packet found
 }
 
 // ************