Q: How do I use the Terrain Analysis Package (TAP)™ software for point to point studies.

A: TAP includes a variety of functions that will help in the point to point design process, as described below.

Use the Point Elevation function (under the Map menu in TAP6) to determine the elevation of a site given the coordinates of the location. This enables you to compare the elevations of several sites in the area of interest. The Point Elevation form also includes an option to find the maximum elevation within a user-specified radius of a location. The topographic elevation data files provide the elevation of the potential sites. Naturally, final site selection should be based on elevations determined from a detailed USGS map or other source.

Use the Area Grid function (under the 3DDisplay menu in TAP6) to extract the elevation values over a rectangular area. The data values can then be plotted in SoftWright's 3DDisplay program (or SURFER or other 2-D or 3-D plotting software) to give you a visual overview of the area, which may be useful in selecting potential sites.  The HDMapper program also includes a function to Export 3DDisplay Files that will create the area grid and coverage information for use in 3DDisplay.

Use the Shadow Study module (accessible in the HDCoverage function under the Area menu in TAP6) to evaluate line of sight and Fresnel obstructions in the vicinity of a site. The shadow study can create a map showing areas that have line of sight from your base station (or from your remote station), as well as areas that have grazing or blocked paths.  You can add potential obstructions in the area (vegetation, ground clutter, buildings, etc.) using the Surface Feature editor.  These features will be included in determining the shadowing and line of sight locations in the shadow study, and can also be used in the path profiles and field strength studies described below.

For example, suppose the base station site is already determined and you are trying to find the best location for a remote station in a particular area. You can run a shadow study to find the locations in the vicinity where you have the best line of sight or path clearance. Likewise, if you have a known location for a remote site, you can run a shadow study from the remote site to find the best location for a base station. In the case of multiple base stations and multiple remotes, you can use the shadow study function in TAP to run numerous studies to determine the which base station will best serve each of the remote locations.

Use the HDCoverage function (the Area button or menu in TAP6) to compute field strength values at numerous locations, based on the parameters of your base station.  Surface Feature files can be included in the coverage calculations  for a radial, contour, or tile coverage study.  You can also compute the field strength at individual target points, such as telemetry stations.

While the Shadow Study described above can give you general information on the line of sight and Fresnel zone clearance for a point to point path, the actual value of the predicted field strength for different locations can be found from an area coverage study. This information will also be useful in selecting the best sites and the best paths for your point to point system.

You can also set up coverage studies from your remote locations to determine the field strength over the surrounding area. The areas of highest field strength would be a guide to the best base station to serve each of the remote locations.

Use the Path Preview function in HDMapper to get a preliminary idea of the topography between base and remote stations. You can draw a map of the area (from the Map function  in TAP6) and by clicking on locations on the map, a simple preview of the path between the points is displayed.  You can also view path previews on the map displayed when you set up a coverage study in HDCoverage.

Use the Path Profile function (under the Path menu in TAP6) to draw a detailed profile showing the effective curvature of the earth, line of sight, Fresnel zone clearance at your operating frequency, etc. As you move the mouse cursor over the profile, other information about terrain elevation, path clearance, knife-edge losses, etc., is displayed. You can add obstacles ("surface features") on the path to determine the effects of buildings, vegetation, etc., on the line of sight and Fresnel zone clearance. 

Add obstacles in the area that may affect your path. You can import or create a database of buildings, vegetation or other "clutter" to be considered in addition to the topographic data (using the Surface Feature File function under the Editors menu in TAP). Path profiles, shadow studies, field strength studies, etc., can use this "Surface Feature" information to determine line of site, etc., considering buildings, vegetation, or other obstacles on or near the path.  You can also add surface features directly on the profile using the mouse.  You can also use USGS Land Use Land Cover information to determine the location of potential obstructions on a profile of the path.

Compute the needed antenna heights at each end of the path. You can use the Antenna Elevation function (in HDPath in TAP6) to determine the height of the antenna at one or both ends of a path in order to achieve line of sight or Fresnel zone clearance over the intervening terrain and surface obstacles.

Use the Path Reflection Analysis module to determine if there are potential problems on the path resulting from destructive reflections from points on the path.

Enter (or import; see below) the facility information for your base and remote stations. The TAP Fixed Facility database (accessible from numerous forms in TAP, as well as the Editors menu) enables you to create and maintain an extensive database of facility information for base stations, remote stations, repeaters, etc. You can use the Fixed Facility editor in the design process by specifying the transmission lines, antennas, etc., and trying various configurations to meet the path link requirements for your installation.

Once the parameters for a fixed facility have been entered into the database, that information can be used to define path end points, shadow study or field study stations, and so forth. You can use the Fixed Facility database to enter existing facilities, proposed facilities, proposed modifications for existing facilities, etc.