gps的纬度，精度在地图上的显示

double lat=this.fileGpsConnection.Latitude;
double lon=this.fileGpsConnection.Longitude;
if(!(lat>=-90&&lat<=90))return;
if(!(lon>=-180&&lon<=180))return;
ESRI.ArcGIS.Mobile.SpatialReferences.SpatialReference spatialReference=
.SpatialReference;
ESRI.ArcGIS.Mobile.Geometries.Coordinate coordinate=spatialReference.FromWgs84(lon,lat);
gpsLocation=new ESRI.ArcGIS.Mobile.Geometries.Point(coordinate);
this.map.CenterAt(coordinate);