[Tagging] Fixed position GPS receivers

[Alan Mintz]

At 2010-05-20 02:44, Jean-Guilhem Cailton wrote:
>Le 20/05/2010 06:29, John Smith a écrit :
> > Here's a sample generated from NASA site log files:
> >
> > <node id='-1' visible='true' lat='44.463944444444' lon='26.125738888889'>
> > <tag k='fixme' v='not_reviewed' />
> > <tag k='man_made' v='monitoring_station' />
> > <tag k='monitoring:gps' v='yes' />
> > <tag k='monitoring:glonass' v='yes' />
> > <tag k='iers_domes_number' v='11401M001' />
> > <tag k='antenna' v='LEIAT504GG      LEIS' />
> > <tag k='receiver' v='LEICA GRX1200GGPRO' />
> > <tag k='name' v='Bucuresti / Romania' />
> > <tag k='ele' v='143.2' />
> > <tag k='source:url'
> > v='http://igscb.jpl.nasa.gov/igscb/station/log/bucu_20100503.log' />
> > </node>
> >
> > Just to make things more interesting, the lat/lon given for some/all
> > sites are in country or region specific datums, eg Australian
> > locations use GDA94, but the site log file can't automatically be
> > parsed for which datum is used.

And it doesn't even always specify them :(


>Compared with the monitoring sites with other purposes (nice aircraft
>noise tracking site by the way), I thought that at least for the
>positioning systems monitoring sites, precise lat/lon should be available.
>
>Looking at the Toulouse log file (and Bucarest's as well), it seemed to
>use ITRF reference system (International Terrestrial Reference Frame -
>http://itrf.ensg.ign.fr/), apparently fairly close to WGS84 for OSM
>purposes (ftp://itrf.ensg.ign.fr/pub/itrf/WGS84.TXT).

The ITRF values do appear to be precisely what is being measured. However, 
the "Latitude" and "Longitude" below them are not always correctly 
transformed to WGS84. I spot-checked a few in my area, finding one that was 
correct, and some that were off by as much as 100m. I used GeoTrans3 and 
the WGS84 datum for the transformation. I looked up the Wikipedia source 
and was satisfied that this is supposedly sufficient to get within 10 cm.

The lat/lon for BUCU is correct under these circumstances, but that for 
TOUL is not. I get 43 33 38.5307, 1 28 51.2087, 211.655 - ~9 meters away 
from the spec'd lat/lon, which seems closer to what appears to be the 
correct structure in the Bing imagery - the square pad near the edge of the 
building about 2.7m SSW of those coords.

I'd also add ref=* for the 4-char identifier (e.g. BUCU) and start_date 
from Item 1 "Date Installed".

Note that at least one of these IGSC stations (LEEP) was previously 
imported by someone: http://www.openstreetmap.org/browse/node/740570067

--
Alan Mintz <Alan_Mintz+OSM at Earthlink.net>