Review of HF propagation analysis & prediction programs

58 programs at a glance

Unlike the other programs reviewed up to now that are on-the-air oriented, these ones are research-oriented or simulate some properties of shortwaves. Similar programs have been developed in the field of astronomy and many other fields.

Some of these propagation programs are only accessible on the Internet through a web interface and provide their solutions in graphical form. Some amateurs have also developed small applications simulating various ionospheric effects. Using either near-real-time data or renowned functions, most of them show a very high accuracy.

Do not hesitate to give me your feedback with any additional information.

DOS Programs - Non-VOACAP - VOACAP-based

Beacon monitors  -  Web & Research oriented 

PropLab Pro - IRI-2001 - CODE GIM - IRI-2001/TEC - PathSim - IONOS - MICROMUF

PropLab Pro

License, $240

PropLab Pro

PropLab Pro 3 is available since 2007. It comes with a new interface. It is always the best simulation program available to date for the advanced amateur or the professional. 

PropLab Pro is a down-sized version of IRI and includes also the International Geomagnetic Reference Field model (IGRF). It is dedicated to simulation at high resolution and with accuracy of ray-trace signals through a realistic two- or three-dimensional view of the ionosphere.

The ray-tracing mode is like hop-testing as it just goes forward for a given choice of radiation angle and the calculation stops if the trace is lost to infinity or stops in the vicinity of the receiver. But the main problem with that approach is that the hops may either fall short or go beyond the target, making it a slow, iterative process to get the path for RF from point A with point B. Beside that, the user would have to evaluate the suitability of the path, whether the number of E-hops would make it too lossy or otherwise.

The 2-D case comes fairly close to dealing with the problem in a proper sense by putting in the appropriate ionosphere for each hop on the path, considering date, time and SSN. But it does not take into account terrain, such as the slope of the ground nor the nature of the reflecting surface. Taking one hop at a time, the calculation does takes into account the change in height of the ionosphere but not any tilts or gradients. That is left for the 3-D case.

The three-dimensional ray-tracing is based on solving equations of motion for the ray path. There are equations for the path advance along and upward in the great-circle (longitudes) as well as the motion perpendicular to that plane, including the skewing of paths in the HF, mainly to take into account the magneto-ionic effect on the top band of 160 meters (Appleton's theory on gyration of ionospheric electrons).

Here are some features handled by PropLab Pro : Ionospheric Tilts, Chordal Hops, Non-Great-Circle Propagation, Spitzes, Effects of the Earth's Magnetic Field, Ordinary and Extraordinary Rays, Electron collisions, Electron density, Signal Ducting (Inter-Layer Reflections), Gray-Line Enhancements, Signal Strength of Ordinary or Extraordinary Rays, and global maps like MUF, FOT, including antenna radiation patterns.

Now at version 3, PropLab Pro is available for all Windows 32-bit platforms. License from $240. No trial version but a free manual is available. A forum is open to users.

NSSDC/COSPAR/URSI

Free access

IRI-2001

This is a web prediction form based on IRI-2001 model. This interface is dedicated to professionals rather than to amateurs.

IRI stands for International Reference Ionosphere. It is a general ionospheric model sponsored by the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI). 

IRI remains THE reference in propagation matter but very few amateur products uses its power and the accuracy of its functions. Up to date only DXAID by Peter Oldfield and DXAtlas by Alex Shovkoplyas use it.

This form is not really a propagation prediction tool but an interface to plot the electron and ion (O+, H+, He+, O2+, NO+) densities, total electron content, electron, ion and neutral (CIRA-86) temperatures, equatorial vertical ion drift and other parameters. This model is supported by NASA/NSSDC. Cf. the NASA IRI web page for more details.

Since 2012, a new model IRI-2012 is available on the NSSDC FTP website.

The IRI-2001 online version is available on NASA website via the old IRIWeb interface.

IRI-2001 was available for Windows platforms from University of Mass. Lowell site (no more now).

This form is in free access. It requests an active connexion to the Internet and a browser.

University of Berne

Withdrawed

CODE GIM

This is a web interface but it is no more available.

This interface without input screen displays forecasts based on real-time soundings.

Global ionosphere maps (GIM) are generated on a daily basis at CODE using data from about 200 GPS/GLONASS sites of the IGS and other institutions. CODE GIM results correspond to the results for the middle day of a 3-day combination analysis solving for 37 times 256, or 9472 vertical total electron (VTEC) parameters and one common set of satellite and receiver DCB constants.  In this way, discontinuities at day boundaries can be minimized. Furthermore, a time-invariant quality level is achieved. The VTEC content is modeled in a solar-geomagnetic reference frame using a spherical harmonics expansion up to degree and order 15. Piece-wise linear functions are used for representation in the time domain. The time spacing of their vertices is 2 hours, conforming with the epochs of the VTEC maps.

University of Leicester

Withdrawed

IRI-2001/TEC

This was a web prediction form based on IRI-2001 model. However it is no more available.

IRI is a general ionospheric model sponsored by the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI). IRI is the source from which have been derivated various models to name electron density models, electron temperature models, auroral precipitation and conductivity models, F2-peak models, geomagnetic storm model (foF2), etc. It incorporated also the CCIR noise model.

Since its release thirthy years ago, several F2-peak models have been developed for the amateur community among them the VOACAP signal model.

This form plots a global ionosphere map showing the electron concentration (TEC) taking into account several physico-chemical conditions and parameters like the date and frequency. This interfaces is as much dedicated to professionals than to amateurs. It uses indeed an user-friendly front-end written by Richard Beard from University of Leicester, U.K. and displays its forecasts on a color world map in cartesian projection.The same interface is used by the université de Berne in Switzerland to provide a dynamic map of the ionosphere, CODE GIM (see above) but based on a entirely different data processing.

This application managed by Chris Thomas is no more supported since 2004.

AE4JY

Freeware

PathSim

Moe Wheatley, AE4JY, wrote this Windows program in 2000 to simulate various radio propagation conditions. Its main purpose is to be able to take audio input from either a soundcard or wave file, and distort this audio signal in a manner similar to how a signal is distorted by the ionosphere and other affects. This distorted signal can then be sent to a sound card or wave file. This allows comparing various modulation modes against various signal conditions.

The main screen is fairly descriptive of the signal processing paths. Three HF paths are available though usually only two are used.

Each simulation "session" can be titled and saved to a file for future retrieval. A set of canned simulations are included in this zip file and are somewhat standard test conditions.

The input signal is first bandpass filtered and converted to an I/Q complex signal using a Hilbert transform (incorporated in the bandpass filter). Three paths are then created with two of them having a variable time delay. Each path has a spreading frequency selection and a frequency offset parameter. The spreading is performed by low pass filtering a complex AWGN signal to the desired bandwidth and then multiplying by the incoming complex signal.

Each path also has a frequency offset function which is just a complex NCO that is multiplied by the incoming signal. Just the imaginary or real term of the three paths are summed together to create a real output. Basically here's how the S/N ratio is achieved. The AWGN source is filtered by a 3 kHz LP filter to bandwidth limit the noise. The input signal's RMS "voltage" is measured and averaged over a second or so. There are two gain/attenuator blocks that are varied to achieve the desired S/N ratio in dB. The noise and signal are then added to produce the final output signal. A small FFT and real-time output plot are available to monitor output signals. The time plot turns red if you are overdriving the 16 bit soundcard/wavefiles.

For all Windows plateforms. Additional files are available on the author's website (manual, source code, MathCAD files). Requires a computer equipped with a soundcard, and a connexion to a receiver in option if you want to work with real signals.

For all Windows 32-bit platforms.

DL6IAK

Freeware

IONOS

Written in 2000 by Michael Keller, DL6IAK, this very interesting program based on the Watterson model simulates various ionospheric effects for two paths which frequency deviation is ranging between -30 to 30 Hz. Effects simulated are doppler spread fast (0-2000 mHz or 2-80 Hz), time delay for path 2 (0-10 ms), a gaussian noise or SNR at 4 kHz (40 to -40 dB), and drift (0-1120 Hz/min). The input file can be either an internal 1 kHz tone (default), a .WAV file or a signal coming from the soundcard. File output is directed to a .WAV file too.

This program can be used in real working conditions or to simulate some geomagnetic effects (storm, aurora, etc) or more simply the multipath time delay took into account in some advanced propagation prediction programs.

Pete Costello

Withdrawed

MICROMUF

Since December 2004 the form is no more available from Nexus.

This web form has been developed by Pete Costello for Unix. It is based on the first MICROMUF prediction program written for DOS in 1984 by Hans Bakhuizen, Technical Policy Adviser of Radio Netherlands.

This is a point-to-point prediction program using the SSN and locations as inputs. It only displays the MUF as shows the same approximative result as its mentor.

Requests an active connexion to the Internet and a browser.