HF propagation software seems to be full of mysteries. But its all about modeling physics. There are several models around, the most prominent surely is VOACAP, followed by ASAPS. VOACAP comes in very many different tastes like e.g. PropMan 2000 or ACE. It often has been coined to be the “Gold Standard” among hams and professionals as well. VOACAP gives reliable results on a statistical base for a month, whereas ASAPS returns propagation based on the current conditions of a day. It also gives propagation for an aircraft en route during its flight and takes at least a bit care of multi-path propagation which may degrade digital modes. Both work offline as online, and they are fast.
PropLab is giving you a much smarter view on what is really happening on a specific day and time at a specific path or area. It relies on the International Reference Ionosphere (IRI 2007) and uses the ray tracing technique. In short, PropLab is automatically fetching all relevant space weather data (not just sunspots) from scientific sources of the internet to model the ionosphere with its different “layers”.
You then give in your path, antenna etc. in a well-supported way. After having started “ray tracing”, PropLab lets refract rays at exactly this ionosphere with its high granularity and some real-world effect like tilts of layers which will result in e.g. propagation off the great circle. It will also beautifully show effects like focusing and gray line propagation, including Pedersen’s long ranging ray with time resolution up to one second – rather than one hour as that of VOACAP.
This ray tracing can be done in either fast 2D or more time-consuming 3D mode, the latter reflecting both ordinary and extra-ordinary rays plus off-great circle propagation.See the screenshot on top as a 3D example simulating propagation between ALE-station FERB in Far’gona (Fergana)/Uzbekistan and my location in Germany at 16:20 UTC on August 26th, 2016 on 8.066 kHz: elevation of the signal as well as its azimuth had been changed slightly and are drawn into an terrarium-like graphic. Each of the three dimensions has another scale to show all effects as good as possible. I don’t know any other software (after AREPS went out of the public) which only comes near to modeling propagation like real life. One great advance is that it reveals/shows opportunities of short-living propagation which the other software won’t show. Hence, PropLab is an ideal tool for the serious ham and SWL.
The following screenshots take the above path and its data, comparing the advantage of 3D raytracing over 2D raytracing only on a “footprint” map. The data is rather reduced showing the rays around just one main elevation angle of about 8,5°. If you model the antenna characteristics more realistic, the here empty regions will soon be filled with nice signals. But here I want to show nothing more than a DX example.
See this slide show changing between signals with and without extra-ordinary rays. The latter easily reach out much wider in the western direction.
Furthermore, 3D raytracing gives with great lucidity nothing more than an anatomy of propagation. This includes e.g. a synthesized oblique ionogram (2D and 3 D), a dispersion chart showing how a signal is spread over time due to different paths and so on. It includes a worldwide terrain profile, taking into account the different quality and angle of reflections on earth (2D).
I am using this software from its MS-DOS 2’er version, around 20 years ago. It now has arrived at version 3.1, fit for Windows 10. I can absolutely recommend this stunning work of Cary Oler – your shack is not completed without this vital tool. Don’t be scared off by its price tag in times where you expect everything for free: you get an excellent value for your money. And after a while using it you may ask: “How ever can I have lived without it?!”