Rick Muething KN6KB, Tom Lafleur KA6IQA, Tom Whiteside N5TW
This project introduces a practical high-performance stand-alone and OS independent Ionospheric Channel Simulator. Full open source documentation is available here.
A feature article with more detail is in the QEX March/April 2022.
The Amateur Radio Safety Foundation introduces the IONOS Channel Simulator, an audio-processing, 1-4 path (ray) simulator that models common HF and VHF/UHF propagation channels. It is intended to accelerate modem and protocol design, analysis, optimization and comparison, but has other uses as well. It allows off-air laboratory testing and evaluation of radio protocols and modems using statistically-standardized channel characteristics that would be almost impossible to achieve with over-the-air RF testing. Automation features allow scripting for multiple test runs under automatic control for huge time and labor savings. Since no transceivers are needed, the device may also be used as an inexpensive operator training station for exercising and teaching digital mode software. The simulator is based on the well-documented Watterson model [1] used by many laboratory grade instruments costing many thousands of dollars.
What is An Ionospheric Simulator?
Every ham learns that much of our communication relies heavily on radio wave propagation through the Ionosphere layer. This layer reflects radio waves and can create single or multiple hop paths from station to station. While most radio waves involve this type of propagation it is not trivial to model the constantly changing Ionosphere to test and optimize the performance of our radios and protocols. On-air tests are notoriously unpredictable and difficult or impossible to duplicate at another time.
In 1970 a landmark paper by Watterson, Juroshek, and Bensema was presented in the IEEE Transaction on Communication Technology. They described a mathematical process (model) that could fairly accurately model and simulate radio propagation over narrow band HF. This and follow-on papers by others and the CCIR/ITU defined a set of standardized “representative test channels” that would allow computer software or hardware simulators to statistically model HF radio propagation by manipulating the modulating audio. This has been used over the years to develop, test, and improve many of the various digital and digital voice protocol we use today.
A few complete units are available from The Amateur Radio Safety Foundation.
Featured in the March/April 2022 issue of ARRL's QEX Magazine.
BUY IONOS