Extracting GPS coordinates

rvk2 · 06-11-2006, 08:57 PM

Hi everyone,

My team recently ordered a BU-303 GPS unit for a class project. Is there a way to extract the GPS coordinates in Windows? We want to extract the coordinates, save it in a text file and send it to a server.

DJiK · 06-11-2006, 09:25 PM

Yeah, use Hyper Terminal at first.
[

+R, "hypertrm", OK]
Set up the correct port, baud rate, etc.

Since it's constantly updating, you'd eventually want to write a program that reads it line by line and saves to a TXT file after a certain number of lines or seconds.

If you just need a one time example, save/export the text from Hyperterminal to a TXT file and use that for your project.

The sting that you're looking to parse begins with $GPRMC.
And this is what it means:

Code:

$GPRMC

Recommended minimum specific GPS/Transit data

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

--Courtesy of http://www.werple.net.au/~gnb/gps/nmea.html