Friday, March 29, 2019

VOACAP Online services in a nutshell (March 2019 Update)

As I am still receiving emails where people complain about the loss of some of the VOACAP Online services after the renewal of the pages last summer, let me briefly summarize the content of the current VOACAP Online portfolio.

Background: Last year I was forced to revamp all my VOACAP Online services, due to a change in Google Maps policies. At that time, I also consolidated all my services under the same hood, changing the URL in the process. The new URL, as you may have noticed, is now, and it incorporates BOTH the point-to-point prediction services AND coverage area map services. So, instead of reducing the VOACAP Online service portfolio, I have actually expanded it quite considerably.

To understand the new service and how it works, I warmly recommend that you read the new manual at

Let me highlight all the services below; more detailed descriptions can be found in the aforementioned manual:

(1) Prop Charts, or Propagation Charts. Clicking the "Prop Charts" button on the right side of the map display 15 toggleable prediction charts for all amateur radio bands from 10 meters (28 MHz) to 80 meters (3.5 MHz). The charts show e.g. the probability (or, the REL parameter in the VOACAP language) for a communication contact (i.e. a QSO) between the TX and RX sites. The "REL Short-Path" chart is the default.

(2) Prop Wheel. This button on the right margin of the map will display the famous 24-hour Propagation Prediction Wheel, showcasing the REL parameter only. Keep this window open as you move the markers on the map, or change any settings. The predictions will change on the screen on-the-fly!

(3) Band-by-band Prediction, or all Prediction Charts on one page. If you wish to see all the prediction charts displayed on a single page available under the “Predictions” button on the right side of the map, click the button labeled "Band-by-band Prediction" below the map.

(4) Best FREQ. The Best FREQ button below the map provides an assessment of the Best Operating Frequencies for every hour of the day in a month for the circuit chosen. This means that all ham radio bands are being considered and, after a careful evaluation, the three best bands will be displayed, together with some VOACAP prediction data.

(5) REL & SDBW, or the original VOACAP point-to-point prediction graphs. The “REL & SDBW” graphs were the first graphs generated at the VOACAP Online Point-to-Point site, and by pressing this button, the detailed propagation prediction graphs will be calculated for the entire frequency range from 2 MHz to 30 MHz, showing the REL (Circuit reliability) and S DBW (Signal Power) graphs for the circuit.

(6) All-year Prediction, or point-to-point prediction tables for all months available at once. The All-year Prediction calculates the point-to-point predictions for the circuit (from TX to RX), covering the entire year and more if possible. The number of prediction tables generated will depend on the Sunspot Number predictions available from SIDC in Belgium. The colors in the table indicate the probability of making a contact between the TX and RX, using the TX mode selected (WSPR, FT8, CW, SSB or AM). All user-settable input parameters will be observed, except the Sunspot Number (SSN).

(7) QSO Window, know your window of opportunity to work DX! By default, on the interactive map, you will see two markers (for TX and RX). Another five markers can be revealed by clicking the triangle-shaped button on the left side of the map. These are the sites of the "competing" locations that are trying to make a QSO with the DX station, too. Now, for you to able to see your chances in relation to the other five, the QSO Window function runs five extra propagation predictions from the five sites to the DX site (RX), and displays the results as interactive charts where you can easily compare the output values to those from your location.

(8) Season. This service uses the user-entered or automatically determined Sunspot Number (SSN), and calculates the SNR (median signal-to-noise ratio), SDBW (signal power at receiver), and the REL (circuit reliability) values for each month of the year for the given circuit. The results will be displayed in a huge table band by band, together all-year averages of the three output values for each hour of the day, supporting more long-term propagation planning, or to choose the best month for a DXpedition.

(9) Planner, or the Propagation Planner is a comprehensive planning tool for HF contesters and DXers. The results can be viewed zone by zone and band by band from the TX site the user provided. The colors indicate the probability of making a QSO between the TX and the Zone in question.

(10) P2P Grayline, or sunrise/sunset times for the current and next month. The Grayline calculates a wealth of solar-related information for the Transmitter and Receiver, and for the geographical midpoint of the circuit, covering the two months: the current and the following.

(11) Distance. This graph shows how the propagation parameters of REL, MUFday, SNR, and SDBW (Signal Power) develop ALONG the Great-Circle Path from TX to RX. Work in progress.

(12) REL Map & SDBW Map. This service is able to plot coverage area maps featuring REL (circuit reliability) or SDBW (signal power) values. What is more, it can also calculate and display multiple coverage maps at one go. The input values for the coverage maps have a separate section under the “Settings” button on the right margin of the interactive map.

(13) DXCC Grayline, or sunrise/sunset/midnight times for all DXCC entities. The DXCC Grayline calculates the sunrise, sunset and midnight times for all the defined DXCC entities on the current day.

I hope this helps people understand the current offering of the services.