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GPS-20 Operating Manual
Rikaline
Rikaline Marketing Corp.
5F-1, 125, Roosevelt Road, Sec. 5, Taipei, Taiwan 116
Tel: ++886 2 2934 5456 Fax: ++886 2 2934 4373 E-Mail: info@rikaline.com.tw
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4. Software Interface
4.1 NMEA Transmitted Messages
The GPS-20 supported by SiRF Technology Inc. also outputs data in NMEA-0183 format as defined by
the National Marine Electronics Association (NMEA), Standard.
The default communication parameters for NMEA output are 4800 baud, 8 data bits, stop bit, and no
parity.
Table 4-1 NMEA-0183 Output Messages
NMEA Record Description
GPGGA
Global positioning system fixed data
GPGLL Geographic position- latitude/longitude
GPGSA GNSS DOP and active satellites
GPGSV GNSS satellites in view
GPRMC Recommended minimum specific GNSS data
GPVTG Course over ground and ground speed
4.1.1 Global Positioning System Fix Data (GGA)
Table 5-2 contains the values for the following example:
$GPGGA,161229.487,3723.2475,N,12158.3416,W,1,07,1.0,9.0,M, , , ,0000*18
Table 4-2 GGA Data Format
Name Example Units Description
Message ID $GPGGA GGA protocol header
UTC Time 161229.487 Hhmmss.sss
Latitude 3723.2475 ddmm.mmmm
N/S Indicator N N=north or S=south
Longitude 12158.3416 dddmm.mmmm
E/W Indicator W E=east or W=west
Position Fix Indicator 1 See Table 5-3
Satellites Used 07 Range 0 to 12
HDOP 1.0 Horizontal Dilution of Precision
MSL Altitude 9.0 Meters
Units M Meters
Geoid Separation Meters
Units M Meters
Age of Diff. Corr. second Null fields when DGPS is not used
Diff. Ref. Station ID 0000
Checksum *18
<CR> <LF> End of message termination
Table 4-3 Position Fix Indicator
Value Description
0 0 Fix not available or invalid
1 GPS SPS Mode, fix valid
2 Differential GPS, SPS Mode, fix valid
3 GPS PPS Mode, fix valid