AQ-300 Operating Manual
12
Appendix A
Software Interface
The AQ-300 interface protocol is based on the National Marine Electronics
Association's NMEA 0183 ASC
Ⅱ
interface specification, which is defined in
NMEA 0183, Version 2.2 and the Radio Technical Commission for Maritime
Services (RTCM Recommended Standards For Differential Navstar GPS
Service, Version 2.1, RTCM Special Committee No.104).
NMEA
Transmitted
Messages
The AQ-300 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 A-1 NMEA-0183 Output Messages
NMEA Sentence
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
Global Positioning System Fix Data (GGA)
Table A-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 A-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 A-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
