Propagation models

This service offers a variety of propagation models for different purposes, all of which are open source so you can examine the algorithms used for your piece of mind. For maximum speed the models are all written in a low level language (C++). Feedback from radio professionals and developers is encouraged to optimise the models where possible.

Model Description Frequency range Source
Irregular Terrain Model (ITM) 'Longley Rice' Model. US Gov. general purpose model used by FCC 20-20,000MHz itm.cpp
Line of Sight (LOS) Simple model for viewing obstructions 20-100GHz main.cpp
Okumura-Hata (Urban) Hata model for cellular communications in urban areas 150-1500MHz hata.cpp
Okumura-Hata (Sub-urban) Hata model for cellular communications in suburban areas 150-1500MHz hata.cpp
Okumura-Hata (Open) Hata model for cellular communications in open areas 150-1500MHz hata.cpp
COST231-Hata (Urban) European COST231 frequency extension to Hata model for urban areas 1500-2000MHz cost.cpp
ITU-R P.525 Free Space Path Loss model 20-100,000MHz fspl.cpp

Irregular Terrain Model

This service uses the Irregular Terrain Model version 7, also known as the 'Longley Rice' model.
The ITM model is a long standing general purpose model developed by the US NTIA and used by the FCC which meets most radio engineering requirements for frequencies between 20 MHz and 20 GHz. It is suitable for everything RF from handheld VHF walkie-talkies to SHF microwave links. It factors in electromagnetic theory, terrain features, ground clutter and radio measurements to predict the attenuation of a radio signal at a given point on the earth.

Line of Sight (LOS) model

The LOS model is a simpler model well suited to super high frequency microwave links where LOS is key. It factors in terrain data and antenna heights to provide a clear yes/no result. It starts where the ITM model finishes at 20GHz and extends the maximum range up to 100GHz.

Okumura-Hata models

The Hata models were designed for Urban cellular planning which is evident by their focused frequency range (150-1500MHz) and minimum tower elevation of 30m. The model assumes the transmitter is higher than the average height of the rooftops.

COST231-Hata extension

The COST231-Hata model extends the Hata cellular models another 500MHz up to 2000MHz so is well suited to GSM1800 in urban areas.

ITU-R P.525 Free Space Path Loss

The free space model is a very simple model that assumes no obstacles exist between transmitter and receiver. It factors in the frequency and distance. It can be further enhanced with the addition of knife edge diffraction which will factor in terrain obstacles and antenna heights.

Future models

By popular demand we have added new models and are open to requests for more.

Knife edge diffraction

In their native form, the models do not factor in the significant effects of diffraction caused behind obstacles. To accomodate this without the processing overhead associated with recognised complex diffraction theories, a proprietary knife edge diffraction function has been written which simulates diffraction, varied by wavelength and the angle of the received point to the obstacle summit. Knife edge diffraction source

Signal server

The ITM and LOS models are implemented in a program called 'Signal server; which is the open source application that powers cloudRF.
It's a modified version of the popular SPLAT! program, written by John Magliacane and used by the FCC, NASA and engineers worldwide. Signal server is licensed under the GPL so you can download it, and the source code for free at GitHub.