Mapping Tech Tip ~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
When working with the new Trimble Mapping/GIS H-Star products, like the Trimble Geo XH or Pro XH, to achieve optimum post processed accuracy, please follow these rules. When working within approximately 80 miles from the Base Station you plan on getting your post processed corrections from, you want to post process from the closest Base Station only. Do not use an H-Star group of 3 Base Stations, like you normally would. To do this in Trimble Pathfinder Office, select Utilities/Differential Correction. Use the (+) plus symbol to add your collection file or files, then select Next. Select “Automatic H-Star Carrier and Code Phase Processing,” then select Next. Confirm your Correction Settings, then select Next. Under Base Provider Group, hit the Select Button. Select the “New” button to create a new Group. Type in a Name for the Base Station, ie.. St. Cloud Base Only. Hit the (+) plus button to add a Base Station to the Group List. Navigate to the Base Station of choice, then click it to select. Once it is in your list as Provider #1, click OK, then Next. Choose your output folder and output filename settings, then click Start to begin the processing session.
If your Base Station is not in the list and you are close to one of the VRS CORS stations in Minnesota, you can add the Base Station with the details for where the data resides on the Internet. In the Select Base Provider screen, after you have hit the (+) plus button to add your base station of choice, select the New button to enter the details of the Base Station yourself. In the General Tab, give you Base Station a Name. All other commands in this tab are optional. In the Base Station tab, you must enter the position of your Base Station. This information can be seen by going to the following URL using your Internet Provider:  http://rocky.dot.state.mn.us/cors/StationInfo.pdf. When entering the Latitude and Longitude, type in using this example (Latitude: 46.123456N, Longitude 96.123456W). Enter the Height Above Ellipsoid (HAE) in meters. In the Internet Server tab, put in the location URL for the Base Station files. MN DOT Base Stations use the following URL for their Base Stations: ftp://www.olmweb.dot.state.mn.us/CORS.GPS/%YYYY%/Month.%Mmm%/Day.%DD%/Stwv%DDDDD%0.%yy%o.zip. The Only thing that must change is the 4 digit designation for the Base Station of Choice. For example in this URL, “Stwv” refers to the Stewertville Minnesota Base Station. Replace this designation with the Base Station you wish to use based on the list you selected to get the Base Station Position at: http://rocky.dot.state.mn.us/cors/StationInfo.pdf. Each Base Station has this designation. All other settings within this set-up are default and do not need to be changed. Select OK, and now you will see the Base Station you created in the List. These procedures can also be applied to GPS Analyst Software when processing GPS data within ArcMap.