A Technology Blog About Code Development, Architecture, Operating System, Hardware, Tips and Tutorials for Developers.

Thursday, October 28, 2010

NMEA GPS Reads

8:58:00 PM Posted by Satish Kumar , , No comments
GPS modules typically put out a series of standard strings of information, under something called the National Marine Electronics Association (NMEA) protocol. More information on NMEA standard data strings can be found at this site.
GPS receiver gives the reading starting with the following strings and each string appended data has its own significant.
  • $GPGGA: Global Positioning System Fix Data
  • $GPGSV: GPS satellites in view
  • $GPGSA: GPS DOP and active satellites
  • $GPRMC: Recommended minimum specific GPS/Transit data
Each of these sentences contains a wealth of data. For example, here are a few instances of the $GPRMC string.
eg1. $GPRMC,081836,A,3751.65,S,14507.36,E,000.0,360.0,130998,011.3,E*62 eg2. $GPRMC,225446,A,4916.45,N,12311.12,W,000.5,054.7,191194,020.3,E*68
225446 Time of fix 22:54:46 UTC A Navigation receiver warning A = Valid position, V = Warning 4916.45,N Latitude 49 deg. 16.45 min. North 12311.12,W Longitude 123 deg. 11.12 min. West 000.5 Speed over ground, Knots 054.7 Course Made Good, degrees true 191194 UTC Date of fix, 19 November 1994 020.3,E Magnetic variation, 20.3 deg. East *68 mandatory checksum
eg3. $GPRMC,220516,A,5133.82,N,00042.24,W,173.8,231.8,130694,004.2,W*70
1 2 3 4 5 6 7 8 9 10 11 12
 
1 220516 Time Stamp 2 A validity - A-ok, V-invalid 3 5133.82 current Latitude 4 N North/South 5 00042.24 current Longitude 6 W East/West 7 173.8 Speed in knots 8 231.8 True course 9 130694 Date Stamp 10 004.2 Variation 11 W East/West 12 *70 checksum
eg4. for NMEA 0183 version 3.00 active the Mode indicator field is added
$GPRMC,hhmmss.ss,A,llll.ll,a,yyyyy.yy,a,x.x,x.x,ddmmyy,x.x,a,m*hh
Field #
1 = UTC time of fix 2 = Data status (A=Valid position, V=navigation receiver warning) 3 = Latitude of fix 4 = N or S of longitude 5 = Longitude of fix 6 = E or W of longitude 7 = Speed over ground in knots 8 = Track made good in degrees True 9 = UTC date of fix 10= Magnetic variation degrees (Easterly var. subtracts from true course) 11= E or W of magnetic variation 12= Mode indicator, (A=Autonomous, D=Differential, E=Estimated, N=Data not valid) 13 = Checksum
The full documentation you can get here.

Sunday, October 24, 2010

GPS Receiver Module - iW-GPS-01

6:06:00 PM Posted by Satish Kumar , , 2 comments
Got iW-GPS-01(with Active Antenna) and iWave's GPS Platforms. The GPS board is mounted on a GPS platform with serial out and has a external antenna. The board has got a serial port and a power input.The board operates on 5 - 35 V input.

Full specification attached here.

Reads I got from Hiper Terminal.

$GPGSA,A,3,14,06,24,03,30,31,21,22,,,,,2.1,1.0,1.8*3D
$GPGSV,3,1,12,31,72,201,17,22,47,056,15,24,38,314,26,14,37,004,24*72
$GPGSV,3,2,12,18,26,093,,30,26,106,24,06,17,219,25,25,16,084,19*73
$GPGSV,3,3,12,19,14,265,,21,13,150,22,03,13,232,27,16,06,191,*7C
$GPRMC,181611.000,A,1257.7947,N,07740.3910,E,0.16,57.21,231010,,,A*54
$GPVTG,57.21,T,,M,0.16,N,0.3,K,A*38
$GPGGA,181612.000,1257.7948,N,07740.3910,E,1,08,1.0,916.6,M,-88.4,M,,0000*75
$GPGSA,A,3,14,06,24,03,30,31,21,22,,,,,2.1,1.0,1.8*3D
$GPRMC,181612.000,A,1257.7948,N,07740.3910,E,0.40,131.00,231010,,,A*69
$GPVTG,131.00,T,,M,0.40,N,0.7,K,A*0D
$GPGGA,181613.000,1257.7946,N,07740.3911,E,1,08,1.0,917.4,M,-88.4,M,,0000*78
$GPGSA,A,3,14,06,24,03,30,31,21,22,,,,,2.1,1.0,1.8*3D
$GPGSV,3,1,12,31,72,201,17,22,47,056,14,24,38,314,26,14,37,004,24*73
$GPGSV,3,2,12,18,26,093,,30,26,106,24,06,17,219,25,25,16,084,19*73
$GPGSV,3,3,12,19,14,265,,21,13,150,22,03,13,232,27,16,06,191,*7C
$GPRMC,181613.000,A,1257.7946,N,07740.3911,E,0.74,149.98,231010,,,A*6E
$GPVTG,149.98,T,,M,0.74,N,1.4,K,A*06


Some pictures of my setup.





Let play around it.