Terrain Databases

A terrain database is required for area coverage analysis, OHLOSS calculations in interference analysis and the terrain view feature. Single path profiles can also be generated from a terrain data base

Primary and Secondary Databases

The Pathloss program supports a primary and secondary database. This allows a high resolution database with partial coverage to be supplemented with a second database of lower resolution, but complete coverage. An example of this situation is the USGS 1 degree and 7.5 minute digital elevation models in the United States. The 1 degree DEM has a resolution of 3 arc seconds for latitudes less than 50 degrees and has complete coverage. The 7.5 minute DEM has a 30 meter resolution. The coverage of the latter is not complete. One could specify the 7.5 minute DEM as the primary database and the 1 degree DEM as the secondary. A terrain profile would be generated from the 7.5 minute data, where it is available, and default to the 1 degree data if the required files are not available. The program creates a report on the primary and secondary file usage over the profile.

Datum - Coordinate Transformation

If a database is based on the WGS84 datum, the users geographic coordinates will be automatically transformed to this datum for all database operations.

Supported Terrain Database Formats

The following terrain data base formats are currently supported.

USGS 1:250,000 DEMS (3 arc second)
USGS 30 and 10 meter data for 7.5 minute quad mapping
USGS GTOPO30 global 30 arc second terrain data
DTED (Digital terrain elevation data - US DMA format)
CRC - Canadian Research Council)
ESRI (ArcInfo) GRIDASCII in geographic and UTM formats
South African National Exchange Standard
MDT200 and MDT25 - Spain
Odyssey Terrain data in UTM, Swiss, Irish and UK grid formats
Phoenix -Airtouch Cellular format
Micropath - 3 second terrain data
AUSLIG - Australian 3 second terrain data
UK Ordnance Survey
MSI Planet

Formats Under Development

USGS 30 and 10 meter data supplied in SDTS format
DGM - Germany

Pathloss Terrain Data

Both the USGS 1:250,000 3 arc second DEMS and the GTOPO30 global 30 arc second terrain data are available at no charge from the USGS web site.

For Pathloss users in the United States, the program ships with compressed 3 second terrain data for the United States and Alaska on a single CD-ROM. This data has been taken directly from the USGS 1:250,000 DEMS. The Pathloss program reads the compressed data directly.

As a convenience to Pathloss users, the program ships with USGS GTOPO30 data for the world (except for the Antarctic region). The header and elevation data files are supplied in the native USGS format on two CD-ROMS.

Last Update: 06/08/00