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Chapter 9

FAQ and Tips

 

 

9.1Overview of FAQ and Tips

This is a valuable section to pass on some of Waypoint’s processing knowledge to you along with a few tips that can vastly improve certain data sets. Many of the answers to the FAQ and the tips listed for GrafNav can also be applied to baselines in GrafNet.

9.2General FAQ and Tips

9.2.1How can I store Master Station Coordinates?

Every time a new project is created, the software prompts you for the coordinates at the master station. If certain base stations are being used repeatedly, it is easier to store the station coordinates by using Add To Favourites in the Enter Master Position window, and loading the master station coordinates using Select from Favourites when needed. This method is faster and removes the possibility of typing errors.

Station coordinates from network or traverse solutions can also be added to Favourites Manager using GrafNet. Once a network solution has been processed, and you right-click on the station in the Map Window, a menu appears with the Add point to Favourites option. If no network solution is available, the software prompts you to see if the traverse solution should be used instead. Stations added in GrafNet will also be available for use in GrafNav.

If the antenna is permanently mounted, then you can store the antenna height and attributes along with the point coordinates.

It is worth noting here that CORS, IGS, AUSLIG, IGN, and GSI control points are pre-loaded into the Favourites Manager. However, these coordinates should only be used as guidelines, as they are subject to change. Additionally, be careful to note the datum of the coordinates found in the Favourites Manager. For instance, IGS coordinates are given in WGS84. If high accuracies are desired, the exact coordinates should be found via the Internet.

By selecting the datum prior to clicking on the Select from Favourites button, coordinates in this datum are favoured. This has application for stations that are part of two networks, such as CORS and IGS. While CORS coordinates are in NAD83, those from IGS are in ITRF/WGS84.

9.2.2How can I obtain Master Station Coordinates?

For differential processing, accurate master coordinates are very important. The previous section discusses how point coordinates can be stored for easy loading later on. In many situations, the coordinates are either not known or are suspect. The following methods can be used to determine precise coordinates:

1.For permanent stations, consult the Internet for the official published coordinates.

2.The PPP processor can accurately determine base coordinates if there is sufficient dual frequency data available. Such processing requires precise clock and ephemeris files, which are generally available within 24 hours.

3.Use GrafNet in conjunction with two or three nearby permanent stations, which can be downloaded using the Download Service Data utility. Stations should only be used in the project if precise coordinates are available.

4.Submit your data to OPUS, an on-line processor from NGS. This service is free of charge and works well for North American data sets. It computes the coordinates for your submitted station by processing against the nearest CORS stations. It is similar to GrafNet, but without the graphics.

5.Submit your data to SCOUT or Auto GIPSY, which are both free on-line point processors that work well

GrafNav / GrafNet 8.10 User Guide Rev 4

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