diff --git a/libraries/AP_GPS/AP_GPS.cpp b/libraries/AP_GPS/AP_GPS.cpp
index e2e0d623d8..e8b7c9b04e 100644
--- a/libraries/AP_GPS/AP_GPS.cpp
+++ b/libraries/AP_GPS/AP_GPS.cpp
@@ -553,6 +553,32 @@ void AP_GPS::send_blob_start(uint8_t instance, const char *_blob, uint16_t size)
     initblob_state[instance].remaining = size;
 }
 
+/*
+  initialise state for sending binary blob initialisation strings
+ */
+void AP_GPS::send_blob_start(uint8_t instance)
+{
+        if (_type[instance] == GPS_TYPE_UBLOX && (_driver_options & AP_GPS_Backend::DriverOptions::UBX_Use115200)) {
+            static const char blob[] = UBLOX_SET_BINARY_115200;
+            send_blob_start(instance, blob, sizeof(blob));
+        } else if ((_type[instance] == GPS_TYPE_UBLOX_RTK_BASE ||
+                    _type[instance] == GPS_TYPE_UBLOX_RTK_ROVER) &&
+                   ((_driver_options.get() & AP_GPS_Backend::DriverOptions::UBX_MBUseUart2) == 0)) {
+            // we use 460800 when doing moving baseline as we need
+            // more bandwidth. We don't do this if using UART2, as
+            // in that case the RTCMv3 data doesn't go over the
+            // link to the flight controller
+            static const char blob[] = UBLOX_SET_BINARY_460800;
+            send_blob_start(instance, blob, sizeof(blob));
+#if AP_GPS_NMEA_ENABLED
+        } else if (_type[instance] == GPS_TYPE_HEMI) {
+            send_blob_start(instance, AP_GPS_NMEA_HEMISPHERE_INIT_STRING, strlen(AP_GPS_NMEA_HEMISPHERE_INIT_STRING));
+#endif // AP_GPS_NMEA_ENABLED
+        } else {
+            send_blob_start(instance, _initialisation_blob, sizeof(_initialisation_blob));
+        }
+}
+
 /*
   send some more initialisation string bytes if there is room in the
   UART transmit buffer
@@ -684,25 +710,7 @@ void AP_GPS::detect_instance(uint8_t instance)
         dstate->last_baud_change_ms = now;
 
         if (_auto_config >= GPS_AUTO_CONFIG_ENABLE_SERIAL_ONLY && new_gps == nullptr) {
-            if (_type[instance] == GPS_TYPE_UBLOX && (_driver_options & AP_GPS_Backend::DriverOptions::UBX_Use115200)) {
-                static const char blob[] = UBLOX_SET_BINARY_115200;
-                send_blob_start(instance, blob, sizeof(blob));
-            } else if ((_type[instance] == GPS_TYPE_UBLOX_RTK_BASE ||
-                        _type[instance] == GPS_TYPE_UBLOX_RTK_ROVER) &&
-                       ((_driver_options.get() & AP_GPS_Backend::DriverOptions::UBX_MBUseUart2) == 0)) {
-                // we use 460800 when doing moving baseline as we need
-                // more bandwidth. We don't do this if using UART2, as
-                // in that case the RTCMv3 data doesn't go over the
-                // link to the flight controller
-                static const char blob[] = UBLOX_SET_BINARY_460800;
-                send_blob_start(instance, blob, sizeof(blob));
-#if AP_GPS_NMEA_ENABLED
-            } else if (_type[instance] == GPS_TYPE_HEMI) {
-                send_blob_start(instance, AP_GPS_NMEA_HEMISPHERE_INIT_STRING, strlen(AP_GPS_NMEA_HEMISPHERE_INIT_STRING));
-#endif // AP_GPS_NMEA_ENABLED        
-            } else {
-                send_blob_start(instance, _initialisation_blob, sizeof(_initialisation_blob));
-            }
+            send_blob_start(instance);
         }
     }
 
diff --git a/libraries/AP_GPS/AP_GPS.h b/libraries/AP_GPS/AP_GPS.h
index 65c37b2a68..cf73c3985d 100644
--- a/libraries/AP_GPS/AP_GPS.h
+++ b/libraries/AP_GPS/AP_GPS.h
@@ -473,6 +473,7 @@ public:
     bool blend_health_check() const;
 
     // handle sending of initialisation strings to the GPS - only used by backends
+    void send_blob_start(uint8_t instance);
     void send_blob_start(uint8_t instance, const char *_blob, uint16_t size);
     void send_blob_update(uint8_t instance);