Working with DGPS to Get High-accuracy Field Data
Differential GPS uses the differential correction techniques to increase the accuracy of the location data collected by using global positioning system (GPS). The DGPS add-on in the SuperGIS desktop allows users to post-process their location data and enhance the data quality. For example, if you are collecting data in the urban areas where all the human-made features are close to each other, you definitely want to get a high accuracy data. Otherwise chances are you may mistake one building from another. To use the DGPS add-on, there should be a GPS receiver, which is the reference/base station, set up on a known location. The GPS receiver calculates the difference between its position based on satellite signals and its actual location. The difference is the applied to the collected location data to increase the accuracy.
Workflow of Using DGPS add-on
To use DGPS, users should download the data from reference/base stations ahead of time, and use GNSS extension to collect log, rinex, and features during survey. The GNSS extension is one of the powerful extensions in SuperPad. To use it, please turn on the GNSS extension in the settings page. And its icon will show up in the toolbar, as shown in the figure below. Then click the red button to start collecting the field data, including the log, rinex, and the features.
Afterwards, users can apply post-process function of DGPS add-on in SuperGIS Desktop to the data.
Three main steps for using DGPS in SuperGIS Desktop：
1. Download data from reference/base stations
2. Copy the data collected from the mobile devices
3. Use DGPS in SuperGIS Desktop
Download Data from Reference/base Stations
While downloading data from reference/base stations, it is recommended to use the reference/base station within 100 kilometers from the users’ location. Users can link to the hyperlink to find the nearest station: http://www.igs.org/network . The required data include RENIX data and navigation data.
Copy the Data Collected from the Mobile Devices
In addition to downloading the data from the stations, users should also copy the data collected from the mobile devices, including all the related .geo/.shp file, dgps.gnss, Rinex_OBS_(yyyymmddHHMM).txt, POS_(yyyymmddHHMM).txt, Speed_OBS_(yyyymmddhh).txt.
Use DGPS in SuperGIS Desktop
To increase the accuracy of the data, users can run post-process function to the data. By running DGPS add-on in SuperGIS Desktop, users can perform post-processing on the collected data and the downloaded data to obtain the accurate result.