Digital terrain data
Digital elevation models Terrain data is not supplied with the program. The following digital elevation data formats are supported:
SRTM hgt and bil files (1 arc second - USA, 3 arc seconds - world wide)
USGS national elevation data (NED) 1 arc second, 1/3 arc second and 1/9 arc second
USGS ASCII files 1:250,000 3 arc second, 1:24,000 30 meter and 10 meter
DTED Canadian CDED files 1:250,000 (3 arc seconds) and 1: 50,000 (0.75 arc seconds)
ESRI GRIDASCII South Africa NES - Cape datum and ORT - Hartebeesthoek94 datum using Gauss conform projection
USGS GTOPO30 global 30 arc second
USA 3 second compressed CTE format Generic BIL format for both geographic and projected formats
Digital clutter models
The following digital clutter data formats are supported:
1992 and 2001 National land cover data (NLCD)
1 arc second Global Land Cover Characteristics (GLCC)
30 arc seconds Generic BIL format for both geographic and projected formats. (Planet clutter uses a BIL projected format)
Pathloss site database
An ODBC interface (open database connectivity) is provided to connect to a user's database. The connection is defined by the ODBC drivers supplied with the users data base. The database consists of a predefined set of relational tables. Site and link data can be transferred between the database and the network display. In addition, the database can be used in interference calculations with links in the network display.
Antenna and radio data files
A separate application, ant_rad.exe, is used to create and edit radio and antenna data files. This is included with the Pathloss program and is also available separately. There is no charge for this program. Version 4 used a directory search algorithm to locate the radio and antenna data files starting a user specified top level directory. In version 5, the radio - antenna codes (file name without the extension) are used as a key field in a lookup table. This means that the file names must be unique. The radio antenna code name lengths have been increased from 15 characters to 47 characters. File naming strategy becomes an important issue in this arrangement.
The NSMA / TIA antenna ASCII file format is used as the source data for antenna data. Version 4 used separate binary antenna data (mas /vas) files for microwave antennas and for VHF-UHF applications. Version 5 uses a single binary file format (asd) for all antenna technologies. Version 5 can use version 4 antenna data files with no restrictions.
Version 4 radio data files were used for microwave applications only. Version 5 uses an expanded file format (rsd) to all radio technologies including adaptive modulation and land mobile applications. Version 4 used a traffic code consisting of the modulation and capacity (e.g. 16E1-QPSK) as an identifier for different interfering radios. Version 5 will read version 4 radio files and use the same identifier convention; however version 5 radio files use the radio code as the identifier instead of the traffic code.
The documentation is integrated into the program in a compiled html format.
New file formats are used for the network (gr5) and link design (pl5) files. The program can read version 4 gr4 files but these will be saved in the version 5 gr5 format. The program can read and write version 4 pl4 files. Depending on the application and the specific data, some data may be lost when saving in the pl4 file format.
Pathloss Radio Link Design Software Algorithms
Microwave multipath fade probability
Vigants - Barnett
Frequency selective fading methods
Dispersive fade margin (North America)
Equipment signature (ITU 530)
Frequency, space and quad diversity improvement factors are calculated using the methods of Vigants and ITU 530.
The following rain fade algorithms are available:
ITU-R P.530-8 /13
The following sources of high intensity rain statistics data are included:
ITU rain statistics files for regions A to Q
Crane rain statistics files for regions A to G
Public city rain data for North America (Digital Microwave Communications - George Kizer - Wiley)
When using rain statistics files, the program automatically determines the required rain file based on the microwave path center coordinates
Obstruction (K) fading
This algorithm automatically determines the value of K which results in a diffraction loss equal to the thermal fade margin and then determines the probability of this K using the following refractivity data sources:
Public obstruction fading data for North America (Digital Microwave Communications - George Kizer - Wiley)
Diffraction Loss Algorithms
Single and multiple knife edge (Deygout / Epstein - Peterson)
Isolated obstacle (radius)
Tropospheric scatter loss
ATT average (90 - 20(C/F1 + 4)
Two ray optics
Ray tracing techniques are used to simulate ducting using M profiles. These profiles are created using the ITU-R P.453-8 data base for surface and elevated ducts at the microwave path center coordinates.
Microwave Antenna Heights
The clearance requirements for antenna heights on microwave links are determined by clearance criteria consisting of:
the earth radius factor K
a percent of the first Fresnel zone radius
a fixed height
a minimum clearance value.
Two separate clearance criteria can be specified for both the main and diversity antennas to account for variations in K
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