About GPS input and GRASS

[Venkatesh Raghavan]

Hi,
Most of the GPS manufacturers these days claim NMEA (National
Marine Electronics Association) format support.
 I would like to interface a GPS via RS232Cserial
port and possibly the s.in.gps function to get the data into GRASS.
Since NMEA seems to be the standard format, I was wondering
if I could use s.in.gps to directly read the NMEA file.
Clifton Wood has given details about the NMEA format and
Peter Bennett's home page gives additional details of NMEA format and
also lists some software tools.
The URL is http://vancouver-webpages.com/pub/peter/index.html

If it would possible to have some thing like s.in.gps.nmea in GRASS
it would be very useful to me.

Thanks

Venkatesh Raghavan
Osaka City University


An example of  the NMEA output is shown below
Example: $GPGGA,170834,4124.8963,N,08151.6838,W,1,05,1.5,280.2,M,-34.0,M,
,*75

 Name                                         Example Data
Description
 Sentence Identifier                          $GPGGA                 Global
Positioning
System Fix Data                              170834
17:08:34 Z
 Time

 Latitude                                         4124.8963, N
41d 24.8963' N or 41d 24' 54" N

 Longitude                                         08151.6838, W         81d
51.6838' W or 81d 51' 41" W

 Fix Quality:                                     1
   Data is from a GPS fix
 - 0 = Invalid
 - 1 = GPS fix
 - 2 = DGPS fix

 Number of Satellites                         05                        5
Satellites are in view

Horizontal Dilution of Precision (HDOP)    1.5                    Relative
accuracy of
                    horizontal position


 Altitude                                         280.2, M
280.2 meters above
                           mean sea level

 Height of geoid above WGS84 ellipsoid -34.0, M                -34.0 meters

 Time since last DGPS update             blank                    No last
update

 Checksum                                     *75
Used by program to
                              check for transmission

    errors

Jill Schuler wrote:

> Venkatesh,
>
> I'm  not sure what the NMEA format is, but s.in.gps works with a comma
> delimited file.  The file format has 5 fields.  The script extracts
> the fifth field from the 2 to 15 character.  This information is then
> processed with s.in.ascii.
>
> I also have a new version of the command that works with PLGR gps units:
> s.in.gps2.
>
> If you provide me with the format,  I will modify the s.in.gps command
> to fit your format.
>
> Jill