harpreetsingh5/p528

U.S. reference implementation of ITU-R Recommendation P.528 providing propagation path loss predictions for aeronautical mobile and radionavigation services using the VHF, UHF, and SHF bands

Recommendation ITU-R P.528-4 - U.S. Reference Implementation

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 125-15 500 MHz for aeronautical and satellite 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	Path distance between terminals
h_1__meter	double	meter	1.5 <= h_1__meter	Height of the low terminal
h_2__meter	double	meter	1.5 <= h_2__meter	Height of the high terminal
f__mhz	double	MHz	125 <= f__mhz <= 15 500	Frequency
time_percentage	double		0.01 <= time_percentage <= 0.99	Time percentage

Outputs

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

Variable	Type	Units	Description
d__km	double	km	Path distance. Could be slightly different than specified in input variable if within LOS region
A__db	double	dB	Total path loss
A_fs__db	double	dB	Free space path loss
propagation_mode	int		Mode of propagation. 1 = Line of Sight 2 = Diffraction 3 = Troposcatter

Return Codes

Possible return codes, including the corresponding defined constant name as defined in p528.h:

Value	Const Name	Description
0	SUCCESS	Successful execution
1	ERROR_VALIDATION__D_KM	Path distance must be >= 0 km
2	ERROR_VALIDATION__H_1	Low terminal height must be >= 1.5 meters
3	ERROR_VALIDATION__H_2	High terminal height must be >= 1.5 meters
4	ERROR_VALIDATION__TERM_GEO	Low terminal must be <= high terminal height
5	ERROR_VALIDATION__F_MHZ_LOW	Frequency must be >= 125 MHz
6	ERROR_VALIDATION__F_MHZ_HIGH	Frequency must be <= 15 500 MHz
7	ERROR_VALIDATION__PERCENT_LOW	Time percentage must be >= 0.01
8	ERROR_VALIDATION__PERCENT_HIGH	Time percentage must be <= 0.99
10	ERROR_HEIGHT_AND_DISTANCE	Terminals are occupying the same point in space (they are the same height and 0 km apart)
0xFF1	WARNING__DFRAC_TROPO_REGION	Warning that the diffraction and troposcatter model may not be physically consistent with each other. Caution should be taken when using the result
0xFF2	WARNING__LOW_FREQUENCY	Warning that the entered frequency is less than the lower limit specified in P.528. Caution should be taken when using the result

Note: Return codes over 0xFF0 signify warnings occured in the calculation. Use bitwise OR operations to diagnosis, as more than one warning could be possible.

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	time_percentage	A__db
15	10	1 000	500	0.5	-110.0
100	100	15 000	3 600	0.9	-151.2
1 500	15	10 000	5 700	0.1	-299.5

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. h_1__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 2017 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 4.7.2. 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, [phone], [email protected]