Why there is difference in coordinates of GPS and the other application while tracking a point?
GIS is the powerful tool set for collecting, storing, retrieving, transforming, and displaying the spatial data from the real world. GPS (Global positioning system) is a satellite-based radio navigation system. It is a part of GIS. The report consists of tracking of two different points in our GPS system and other system and then comparing the results.
The KMZ file which is generated by tracking KML mark file in Google Earth Pro is used to compare the results with the output generated by My Tracks (GMZ file which is converted to KML file) from the phone device. The distance between the points is measured by the ruler. The horizontal and vertical accuracy is compared, and the table is drawn which gives the comparison of survey marks and GPS marks. The coordinates vary in both the cases.
1. Start Google Earth Pro (GE) by double-clicking on your KMZ file.
2. Set Tools> Options Navigation to ‘Do not automatically tilt while zooming’ to maintain a vertical rather than perspective view.
3. In the Layers pane ensure 3D Buildings is turned off, otherwise trees will obscure your ‘places’.
4. Drag your GPX files from the Windows Explorer file manager into the GE window, and accept the default prompt to Create KML tracks and Adjust altitudes to ground height.
5. Expand Places> Temporary Places> GPS device> Waypoints and right-click each one to rename it with its marker code if you didn’t do this in the field, so that it has the correct label.
6. Compare the accuracy of your GPS marks to the survey marks.
There is a difference of 8.42 metres and 8.22 metres in the case of A56K and DK9R respectively for actual and GPS survey points.
Many factors might be responsible for the difference in GPS and other server points. The GPS system is entirely based on the satellite system. Hence the rays that are captured by the device which are coming from the satellite may depend upon the position of satellite and the angle from which the server point is captured. So, the coordinates are not exactly same in both the cases.
The second observation regarding the difference in results for GPS servers for different devices might be the result of varying features and configurations for each device and the positioning of the device while capturing the points. Different angles for capturing the satellite rays by different devices may also result in accuracy variation.
It can also be noted that vertical distance is less than the horizontal distance. So, vertical distance is the more accurate criteria for tracking various points.