Recommendation ITU-R P.528-5 - U.S. Reference Implementation

Persistent Identifier:

This code repository contains the U.S. Reference Software Implementation of Recommendation ITU-R P.528. This Recommendation contains a method for predicting basic transmission loss in the frequency range 100-30 000 MHz for aeronautical services. The software implements Annex 2 of Rec P.528, the Step-by-Step method to computing propagation loss for air-to-ground paths.

Companion software (p528-gui) provides a Graphical User Interface (GUI) that can be used with this software implementation.

Inputs

| Variable | Type | Units | Limits | Description | |-------------------|--------|-------|--------------|--------------| | d__km | double | km | 0 <= d__km | Great circle path distance between terminals | | h_1__meter | double | meter | 1.5 <= h_1__meter <= 20 000 | Height of the low terminal | | h_2__meter | double | meter | 1.5 <= h_2__meter <= 20 000 | Height of the high terminal | | f__mhz | double | MHz | 100 <= f__mhz <= 30 000 | Frequency | | T_pol | int | | | Polarization

• 0 = Horizontal
• 1 = Vertical

| | time | double | | 1 <= time <= 99 | Time percentage |

Outputs

Outputs to P.528 are contained within a defined Results structure.

| Variable | Type | Units | Description | |------------|--------|-------|-------------| | d__km | double | km | Great circle path distance. Could be slightly different than specified in input variable if within LOS region | | A__db | double | dB | Basic transmission loss | | A_fs__db | double | dB | Free space basic transmission loss | | A_a__db | double | dB | Median atmospheric absorption loss | | theta_h1__rad | double | rad | Elevation angle of the ray at the low terminal | | propagation_mode | int | | Mode of propagation

• 1 = Line of Sight
• 2 = Diffraction
• 3 = Troposcatter

| | warnings | int | | Warning flags |

Error Codes and Warning Flags

P.528 supports a defined list of error codes and warning flags. A complete list can be found here.

Example Values

The below table includes a select set of example inputs and outputs for testing purposes. The P.528 CSV data files contain an extensive set of validation example values.

| d__km | h_1__meter | h_2__meter | f__mhz | T_pol | time | A__db | | --------|--------------|--------------|----------|---------|--------|---------| | 15 | 10 | 1 000 | 500 | 0 | 50 | 110.0 | | 100 | 100 | 15 000 | 3 600 | 0 | 90 | 151.6 | | 1 500 | 15 | 10 000 | 5 700 | 0 | 10 | 293.4 | | 30 | 8 | 20 000 | 22 000 | 1 | 50 | 151.1 |

Notes on Code Style

• In general, variables follow the naming convention in which a single underscore denotes a subscript (pseudo-LaTeX format), where a double underscore is followed by the units, i.e. h1_meter.
• Variables are named to match their corresponding mathematical variables in the underlying Recommendation text.
• Wherever possible, equation numbers are provided. It is assumed that a user reviewing this source code would have a copy of the Recommendation's text available as a primary reference.

Configure and Build

C++ Software

The software is designed to be built into a DLL (or corresponding library for non-Windows systems). The source code can be built for any OS that supports the standard C++ libraries. A Visual Studio 2019 project file is provided for Windows users to support the build process and configuration.

C#/.NET Wrapper Software

The .NET support of P.528 consists of a simple pass-through wrapper around the native DLL. It is compiled to target .NET Framework 4.8. Distribution and updates are provided through the published NuGet package.

References

• Recommendation ITU-R P.528
• Rec ITU-R P.528 GUI

Contact

For questions, contact Billy Kozma, wkozma@ntia.gov