Saturday, July 18, 2015

VOACAP Propagation Planner Revisited!

UPDATE July 2017: MUFday assessments in place for all HF propagation prediction tables, resulting in even better predictions on Above-the-MUF frequencies. Read more!

VOACAP Propagation Planner is a comprehensive planning tool for HF contesters and DXers. So far, the only problem has been that you really must be a dedicated enthusiast to run all the software required to maximize your efforts either in contests or DXpeditions. Now, things have changed: A new, more user-friendly version — 2.0 beta — is finally available!

Preparing and planning for any worldwide contest or DX expedition (or hunting a DX) require a thorough analysis of propagation predictions. The propagation predictions help you, so to speak, get a good grasp of the playing field, i.e. where to play and when. The predictions tell you when and on what bands the best openings are in the given direction at a suitable signal strength, so that the QSO rates can be maintained at their best; at what times it’s good to use those valuable long-path openings, and when to focus on working those hard-to-reach areas while the band opens elsewhere at the same time.

The new online version now does all heavy-lifting and number-crunching on the VOACAP server, and visualizes the results in two ways: by CQ or ITU Zones (short-path or long-path) and by band-specific zone charts (short-path or long-path, as you wish). Be warned that there are quite a number of charts to analyze but I am confident all your efforts will greatly be paid off. The tables can easily be copied to word-processing software if you wish to make them fit better on paper. I strongly recommend using the Google Chrome browser to browse the pages as I found that some of the mainstream browsers on some platforms have hard time printing (and even copying) table cells with a background color.

It all boils down to making optimum use of the openings — being in the right place at the right time. So, the better predictions you have, the better basis for operating planning. Nevertheless, we must remember that predictions are just that — predictions, not exact science. And, due to the nature of VOACAP, you must visualize low-band openings with the help of grayline map software such as DX Atlas by Alex VE3NEA or GeoClock by Joe Ahlgren. VOACAP predictions are not so accurate there.

Here are some screenshots of the renewed service:

1. VOACAP Propagation Planner,

The home page of VOACAP Propagation Planner. Please note that you can enter your Maidenhead Grid Locator into the Name ("TX") field and press the "Loc calc" button. The program will calculate the latitude and longitude values respectively.

2. The Propagation Prediction Charts

The results can be viewed zone by zone from the TX site the user provided. The colors indicate the probability of making a QSO between the TX and the Zone in question.

A cropped example of zone-specific predictions.
The elements of the top row are as follows (from left): CQ/ITU zone number, Path from TX to zone, Short-path (SP) or Long-path (LP), month and year, followed by the distance (kilometers & miles) of the circuit, and the bearing (in degrees) from TX to RX.

Below each chart, the sunrise and sunset times for TX and RX locations have been calculated and visually presented as horizontal bars. The silver color denotes night-time and white day-time. The exact sunrise (SR) and sunset (SS) times (in UTC) will come up as you hover the mouse over the TX and RX label texts on the left column. Here, in this example, the TX is "enjoying" the polar night so the sun will not rise at all. The date used in the calculations is always the 15th day of the given month.

All charts are interactive: if you hover your mouse over table cells, you will see a pop-up text, indicating the (VOACAP's REL) probability in percents, and the (VOACAP's S DBW) signal power values in dBW. For instance, the signal power value of -164 can be considered to be on the verge of the noise in remote locations whereas -93 corresponds to S9 on the S meter. Read more about translating the signal power values (S DBW) into S-meter values here: .

The left-hand side column shows the Zone number and the location within the zone. Many zones are geographically wide so, in many cases, a number of locations have been chosen from that zone to give a fair picture of the propagation possibilities.

All colors - except grey - indicate QSO-making probabilities. White means 0%, blueish 10%, greenish 30-40%, yellowish 50-60%, yellow-orangeish 70-80% and orange-reddish 90%, and pure red 100%. The color of grey does not indicate any probability value. Instead, it shows that, although VOACAP does not predict any probability for that specific hour, some signal power has been predicted which may translate into workable conditions. So, in a sense, grey indicates "a grey area" where QSOs may be possible. Typically, these grey areas can mostly be found in low-band predictions charts.

Propagation predictions use a color scheme from white to red.

All predictions charts start at 01 hours UTC. You may ask, "Why not start at 00 UTC?". Well, it's a matter of taste. All VOACAP predictions span 60 minutes but not necessarily the way you may think. A prediction for 01 UTC does not span from 01:00 to 02:00 but, in fact, from 00:30 to 01:30 UTC! So, I decided, being inspired by the original makers of VOACAP, to start at 01 UTC and end at 24 UTC. Following the same logic, 24 UTC means a time frame of 23:30 to 00:30 UTC.


  1. Thanks a lot for this new great tool! 73

  2. A Romanian translation of this article is published at
    Thank you, Jari, 73!
    Fery, YO4PX

  3. Great tool once one gets one''s head around it! Is it possible to add quads and loops to the antennas list?

  4. I'm wondering whether is the "old" plain txt output is still available somewhere? I extended the original xls with coupe of feature and it was way easier to handle it offline. Could you please check the possibility to make it available again?

    Thanks a lot in advance.
    Csaba HA3LN

  5. Hi, the plain text prediction output is available on the result page by adding "prediction.txt" to the end of the URL. E.g. your result page is: , then the prediction output is here: ...

    Hope this is what you want,
    73 Jari OH6BG