Added flight mode build flag

src/gps/GPS.cpp

@@ -545,6 +545,12 @@ bool GPS::setup()
         } else if (gnssModel == GNSS_MODEL_ATGM336H) {
             // Set the intial configuration of the device - these _should_ work for most AT6558 devices
             msglen = makeCASPacket(0x06, 0x07, sizeof(_message_CAS_CFG_NAVX_CONF), _message_CAS_CFG_NAVX_CONF);
+
+#ifdef USERPREFS_GPS_FLIGHT_MODE
+            if (USERPREFS_GPS_FLIGHT_MODE) {
+                msglen = makeCASPacket(0x06, 0x07, sizeof(_message_CAS_CFG_NAVX_CONF_FLIGHT), _message_CAS_CFG_NAVX_CONF_FLIGHT);
+            }
+#endif
             _serial_gps->write(UBXscratch, msglen);
             if (getACKCas(0x06, 0x07, 250) != GNSS_RESPONSE_OK) {
                 LOG_WARN("ATGM336H: Could not set Config");
@@ -670,6 +676,11 @@ bool GPS::setup()
             }
             // Turn off unwanted NMEA messages, set update rate
             SEND_UBX_PACKET(0x06, 0x08, _message_1HZ, "set GPS update rate", 500);
+#ifdef USERPREFS_GPS_FLIGHT_MODE
+            if (USERPREFS_GPS_FLIGHT_MODE) {
+                SEND_UBX_PACKET(0x06, 0x24, _message_NAV5_FLIGHT, "enable flight mode", 500);
+            }
+#endif
             SEND_UBX_PACKET(0x06, 0x01, _message_GLL, "disable NMEA GLL", 500);
             SEND_UBX_PACKET(0x06, 0x01, _message_GSA, "enable NMEA GSA", 500);
             SEND_UBX_PACKET(0x06, 0x01, _message_GSV, "disable NMEA GSV", 500);

src/gps/cas.h

@@ -61,3 +61,26 @@ static const uint8_t _message_CAS_CFG_NAVX_CONF[] = {
     0x00, 0x00, 0x00, 0x00, // Time Accuracy Max
     0x00, 0x00, 0x00, 0x00  // Static Hold Threshold
 };
+
+static const uint8_t _message_CAS_CFG_NAVX_CONF_FLIGHT[] = {
+    0x03, 0x01, 0x00, 0x00, // Update Mask: Dynamic Mode, Fix Mode, Nav Settings
+    0x06,                   // Dynamic Mode: flight <2g
+    0x03,                   // Fix Mode: Auto 2D/3D
+    0x00,                   // Min SV
+    0x00,                   // Max SVs
+    0x00,                   // Min CNO
+    0x00,                   // Reserved1
+    0x00,                   // Init 3D fix
+    0x00,                   // Min Elevation
+    0x00,                   // Dr Limit
+    0x07,                   // Nav System: 2^0 = GPS, 2^1 = BDS 2^2 = GLONASS: 2^3
+                            // 3=GPS+BDS, 7=GPS+BDS+GLONASS
+    0x00, 0x00,             // Rollover Week
+    0x00, 0x00, 0x00, 0x00, // Fix Altitude
+    0x00, 0x00, 0x00, 0x00, // Fix Height Error
+    0x00, 0x00, 0x00, 0x00, // PDOP Maximum
+    0x00, 0x00, 0x00, 0x00, // TDOP Maximum
+    0x00, 0x00, 0x00, 0x00, // Position Accuracy Max
+    0x00, 0x00, 0x00, 0x00, // Time Accuracy Max
+    0x00, 0x00, 0x00, 0x00  // Static Hold Threshold
+};

src/gps/ubx.h

@@ -194,6 +194,26 @@ static const uint8_t _message_NAVX5_8[] = {
     0x00                    // useAdr
 };
 
+// Flight mode
+static const uint8_t _message_NAV5_FLIGHT[] PROGMEM = {
+    0xFF, 0xFF,             // mask
+    0x06,                   // dynModel
+    0x02,                   // fixMode
+    0x00, 0x00, 0x00, 0x00, // fixedAlt
+    0x00, 0x00, 0x00, 0x00, // fixedAltVar
+    0x05,                   // minElev
+    0x00,                   // drLimit
+    0xFA, 0x00,             // pDop
+    0xFA, 0x00,             // tDop
+    0x64, 0x00,             // pAcc
+    0x2C, 0x01,             // tAcc
+    0x00,                   // staticHoldThresh
+    0x00,                   // dgpsTimeOut
+    0x00, 0x00, 0x00, 0x00, // reserved2
+    0x00, 0x00, 0x00, 0x00, // reserved3
+    0x00, 0x00, 0x00, 0x00  // reserved4
+};
+
 // Set GPS update rate to 1Hz
 // Lowering the update rate helps to save power.
 // Additionally, for some new modules like the M9/M10, an update rate lower than 5Hz

userPrefs.jsonc

@@ -29,6 +29,7 @@
   // "USERPREFS_FIXED_GPS_LON": "2.294508368",
   // "USERPREFS_CONFIG_SMART_POSITION_ENABLED": "false",
   // "USERPREFS_CONFIG_GPS_UPDATE_INTERVAL": "600",
+  // "USERPREFS_GPS_FLIGHT_MODE": "true",
   // "USERPREFS_CONFIG_POSITION_BROADCAST_INTERVAL": "1800",
   // "USERPREFS_LORACONFIG_CHANNEL_NUM": "31",
   // "USERPREFS_LORACONFIG_MODEM_PRESET": "meshtastic_Config_LoRaConfig_ModemPreset_SHORT_FAST",