px4-firmware/msg/vehicle_gps_position.msg

# GPS position in WGS84 coordinates.
# the auto-generated field 'timestamp' is for the position & velocity (microseconds)
int32 lat			# Latitude in 1E-7 degrees
int32 lon			# Longitude in 1E-7 degrees 
int32 alt			# Altitude in 1E-3 meters above MSL, (millimetres)
int32 alt_ellipsoid 		# Altitude in 1E-3 meters bove Ellipsoid, (millimetres)

float32 s_variance_m_s		# GPS speed accuracy estimate, (metres/sec)
float32 c_variance_rad		# GPS course accuracy estimate, (radians) 
uint8 fix_type # 0-1: no fix, 2: 2D fix, 3: 3D fix, 4: RTCM code differential, 5: Real-Time Kinematic, float, 6: Real-Time Kinematic, fixed, 8: Extrapolated. Some applications will not use the value of this field unless it is at least two, so always correctly fill in the fix.   

float32 eph			# GPS horizontal position accuracy (metres)
float32 epv			# GPS vertical position accuracy (metres)

float32 hdop			# Horizontal dilution of precision
float32 vdop			# Vertical dilution of precision

int32 noise_per_ms		# GPS noise per millisecond
int32 jamming_indicator		# indicates jamming is occurring

float32 vel_m_s			# GPS ground speed, (metres/sec) 
float32 vel_n_m_s		# GPS North velocity, (metres/sec) 
float32 vel_e_m_s		# GPS East velocity, (metres/sec)
float32 vel_d_m_s		# GPS Down velocity, (metres/sec) 
float32 cog_rad			# Course over ground (NOT heading, but direction of movement), -PI..PI, (radians) 
bool vel_ned_valid		# True if NED velocity is valid 

int32 timestamp_time_relative	# timestamp + timestamp_time_relative = Time of the UTC timestamp since system start, (microseconds)
uint64 time_utc_usec		# Timestamp (microseconds, UTC), this is the timestamp which comes from the gps module. It might be unavailable right after cold start, indicated by a value of 0 

uint8 satellites_used		# Number of satellites used