Visit the where am I page to get all the details of your current location coordinates. You can also find the location of any GPS coordinates, and geocode its address if available. Use this map to convert any address in its GPS coordinates. Again, be sure that the setting in your GPS matches the Coordinate Preference selected in Terrain Navigator.GPS coordinates are formed by two components that are a latitude, giving the north-south position, and a longitude, giving the east-west position. Latitude/Longitude can be expressed in Degrees Minutes Seconds (Dº M' S"), Degrees Minutes (Dº M.M'), and Decimal Degrees (D.Dº). (If you are not sure the datum of your coordinates, WGS84 is usually a safe bet.)Īlso, be sure that the format of the coordiates match exactly.
Set the datum in Terrain Navigator (in the Coordinate Preferences) to match that of the GPS before entering coordinates. If your coordinates are off a little bit, you may be looking at a datum shift. Generally speaking, GPSs report their coordinates in WGS84 datum. Other factors that can give the impression of a false location include the use of different datums, and/or the use of a different coordinate format. Although the government reserves the right to reinstate this 'Selective Availability' during times of military campaigns, civilians can now enjoy the full pin-point accuracy that GPS provides. Additional information can be obtained from the USGS website: Until May 2000, GPS readings could have been off as much as 100 meters (110 yards or 328 feet). USGS 7.5-minute quads adhere to "National Map Accuracy Standards." In a nutshell, this means that a 1:24,000 scale map is accurate within 40 feet. Even large buildings on one or more sides of the GPS unit will skew the signal coming from the satellites.Īlso, although USGS topographic maps are the finest and most accurate available, they are not perfect. When accuracy is critical, ensure that the GPS unit has a clear view of the sky, free of any obstructions.
In general, if there are fewer than four satellites in view, the accuracy of the reading will be compromised. When obtaining a position, it is important to note the number of satellites in view at the time of the reading. Although (at worst) these factors can drive your readings off by several hundred feet, in practice, you should still be able to obtain very usable results. ← GPS: Connectivity, Configuration, and Troubleshooting There are two major factors that can contribute to inaccurate position locations: Satellite Coverage, and imperfections on the USGS map.
0 kommentar(er)
