Converting Lat/Lon from GPS

Hiya,

I've got to convert NMEA latitude/longitude into the following format
(milliseconds?) but don't know how.

Here is an example lat/lon, first in the format it is supposed to be
in, and then two normal examples of the lat/lon at roughly the same
location (to a couple of metres or so)

Any ideas!!!!!!!! Please help?

UK, Birmingham, Nr J7a M42, Coleshill Heath Road

Latitude
-6154441

Longitude
188921104


latitude
54.4809 degrees

longitude
-1.7096 degrees


latitude
52:28:51N

Longitude
1:42:35W

 

See: http://williams.best.vwh.net/avform.htm
http://www.ngs.noaa.gov/TOOLS
http://www.ngs.noaa.gov/PC_PROD/pc_prod.shtml
http://home.hiwaay.net/~taylorc/toolbox/geodesy/datumtrans/
http://users.erols.com/dlwilson/gpsfaq.htm
http://www.posc.org/Epicentre.2_2/DataModel/ExamplesofUsage/eu_cs.html
http://joe.mehaffey.com/transformation.htm
http://www.edu-observatory.org/maps/waypoints.html

 

(Steve) wrote in

WGS84 datum:
N54 degrees 28minutes 51.2400seconds W1 degree 42minutes 34.5600seconds
is the same as:
54° 28' 51.24"N 1° 42' 34.56"W
54° 28.8540'N 1° 42.5760'W
54.480900°N 1.709600°W
54.480900° latitude -1.709600° longitude
http://home.online.no/~sigurdhu/Deg_formats.htm

Now, you want this converted to something like:
Latitude -6154441 Longitude 188921104
I don't know what format that is using, but it seems
odd to be using a negative value for the latitude.
In what context is this format being seen or used?

 

Well there are 60 minutes in each degree, 60 seconds in each minute, and 1000
milliseconds in each second

So 1.7096 * 3600000 = 6154560 -ve because it is West rather than East of
Greenwich

And 52.4809 * 3600000 = 188931240 (Your type of 54.4809 had me fooled for a
while!)


Easy Peasy


Michael Chare

..

 

Except that the OP said that the value of -6154441 is the
Latitude(i.e. N/S), not the Longitude which is what you
have used in your solution ;-)

 

Well spotted, I will crawl away suitably admonished.


Michael Chare

 

Dave Patton wrote ...

He has obviously just transposed the lat/long values in milli-arcsec. The
conversion is simply from dms to decimal degrees then multiply by 3600 to
convert to arc seconds and by a further factor of 1000 because the target
format is an integral number of milliseconds. His measured coordinates are
in the correct order for his stated location (with the exception of his 54
degree typo as already pointed out).

My estimate of the location of the Coleshill Heath Road motorway bridge is
52d28m50s North, 001d42m37s West giving 188,930,000ms North, -6,157,000ms
East in good agreement with the above.

David