$GPGGA,181908.00,3404.7041778,N,07044.3966270,
W,4,13,1.00,495.144,M,29.200,M,0.10,0000*40
All NMEA messages start with the $ character, and each data field is separated by a comma.
GP represent that it is a GPS position (GL would denote GLONASS).
181908.00 is the time stamp: UTC time in hours, minutes and seconds.
3404.7041778 is the latitude in the DDMM.MMMMM format. Decimal places are variable.
N denotes north latitude.
07044.3966270 is the longitude in the DDDMM.MMMMM format. Decimal places are variable.
W denotes west longitude.
4 denotes the Quality Indicator:
1 = Uncorrected coordinate
2 = Differentially correct coordinate (e.g., WAAS, DGPS)
4 = RTK Fix coordinate (centimeter precision)
5 = RTK Float (decimeter precision.
13 denotes number of satellites used in the coordinate.
1.0 denotes the HDOP (horizontal dilution of precision).
495.144 denotes altitude of the antenna.
M denotes units of altitude (eg. Meters or Feet)
29.200 denotes the geoidal separation (subtract this from the altitude of the antenna to arrive at the Height Above Ellipsoid (HAE).
M denotes the units used by the geoidal separation.
1.0 denotes the age of the correction (if any).
0000 denotes the correction station ID (if any).
*40 denotes the checksum.
The $GPGGA is a basic GPS NMEA message. There are alternative and companion NMEA messages that provide similar or additional information.
Here are a couple of popular NMEA messages similar to the $GPGGA message with GPS coordinates in them (these can possibly be used as an alternative to the $GPGGA message):
$GPGLL, $GPRMC
In addition to NMEA messages that contain a GPS coordinate, several companion NMEA messages offer additional information besides the GPS coordinate. Following are some of the common ones:
$GPGSA – Detailed GPS DOP and detailed satellite tracking information (eg. individual satellite numbers). $GNGSA for GNSS receivers.
$GPGSV – Detailed GPS satellite information such as azimuth and elevation of each satellite being tracked. $GNGSV for GNSS receivers.
$GPVTG – Speed over ground and tracking offset.
$GPGST – Estimated horizontal and vertical precision. $GNGST for GNSS receivers.
Rarely does the $GPGGA message have enough information by itself. For example, the following screen requires: $GPGGA, $GPGSA, $GPGSV.
The following screen, focused on the time capabilities of GPS, requires a slightly different set of NMEA messages: $GPGGA or $GPRMC or $GPZDA, $GPGSA, $GPGSV.
- 經度
- 緯度
- 定位完成代號
- 採用有效的衛星顆數
- 所用的衛星編號，及仰角，方向角，接收訊號強度。
- 衛星方位角
- 高度
- 相對位移位移速度
- 相對位移位移方向角度
- 日期
- UTC時間
- DOP誤差參考值
- 衛星狀態及接收狀態
NMEA-0183 輸出資訊表
NMEA 種類 說明
GGA 衛星定位資訊。
GLL 基本地理位置-經度及緯度
GSA GNSS DOP（誤差資訊）
GSV GNSS 天空範圍內的衛星
RMC 基本定位資訊（指已達到定位目的時）
VTG 相對位移方向及相對位移速度
