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The NCDXF (Northern California DX Foundation), in cooperation with the IARU, has constructed and operates a worldwide network of high-frequency radio beacons on 14.100, 18.110, 21.150, 24.930, and 28.200 MHz. These beacons help both amateur and commercial high-frequency radio users assess the current condition of the ionosphere.

These automatic beacon stations transmit every three minutes on the given frequency, 24 hours a day. A transmission consists of the callsign sent in Morse code at 22 words per minute followed by four one-second dashes. The callsign and the first dash are sent at 100 watts. The remaining dashes are sent at 10 watts, 1 watt and 0.1 watts.

The current NCDXF beacon list is as follows:

    DX Entity       Call   Location         Lat      Lon

1   United Nations  4U1UN  New York City    40 45 N   73 58 W
2   Canada          VE8AT  Eureka, Nunavut  79 59 N   85 57 W
3   United States   W6WX   Mt. Umunhum      37 09 N  121 54 W
4   Hawaii          KH6WO  Laie             21 38 N  157 55 W
5   New Zealand     ZL6B   Masterton        41 03 S  175 36 E
6   Australia       VK6RBP Rolystone        32 06 S  116 03 E
7   Japan           JA2IGY Mt. Asama        34 27 N  136 47 E
8   Russia          RR9O   Novosibirsk      54 59 N   82 54 E
9   Hong Kong       VR2B   Hong Kong        22 16 N  114 09 E
10  Sri Lanka       4S7B   Colombo           6 54 N   79 52 E
11  South Africa    ZS6DN  Pretoria         25 54 S   28 16 E
12  Kenya           5Z4B   Kiambu            1 01 S   37 03 E
13  Israel          4X6TU  Tel Aviv         32 03 N   34 46 E
14  Finland         OH2B   Karkkila         60 32 N   24 06 E
15  Madeira         CS3B   Santo da Serra   32 43 N   16 48 W
16  Argentina       LU4AA  Buenos Aires     34 37 S   58 21 W
17  Peru            OA4B   Lima             12 04 S   76 57 W
18  Venezuela       YV5B   Caracas          10 25 N   66 51 W

Each station consists of a 100W transceiver and a vertical antenna.

Setting VOACAP input values

Just follow the nine easy steps below to set up your VOACAP correctly (we suppose you have made the default VOACAP installation at C:\itshfbc):

• Download ncdxf.zip (containing all user input data preset).
• Unzip ncdxf.zip (unzipped: ncdxf.voa) to the C:\itshfbc\saved\default\ directory.
• Create a directory called "user" under the C:\itshfbc\antennas directory.
• Unzip the following files to the C:\itshfbc\antennas\user directory: rxgp.zip (unzipped: rxgp.ant) and txgp.zip (unzipped: txgp.ant). These antenna files contain the typical pattern for a vertical antenna and will be used in the calculations. The files are courtesy of Fabio Bonucci, IK0IXI.
• Launch VOACAP.
• Open ncdxf.voa from the File menu (File > Open).
• Set the appropriate month and SSN (Smoothed Sunspot Number) to "Groups". The current SSN numbers can be downloaded from National Geophysical Data Center (Predicted Monthly Sunspot Numbers).
• Set the "Transmitter" location by choosing the location from a list that comes with the VOACAP package (ncdxf.geo), or by entering the transmitter location and coordinates manually.
• Set the "Receiver" location, e.g. the coordinates of your location.

Running the predictions

• Run the graphical prediction by choosing Graph from the Run menu (Run > Graph).
• When the calculations are done, you will be prompted to choose the output parameter you are interested in. Choose REL (Time availability, % time SNR exceeds required SNR).

The different colours will indicate the reliability (%) to achieve the required SNR for communication. The best reliability is shown in white and the worst in dark gray. Look at the colour legend for values.

Now when you are all set, try running the circuit analyses from various NCDXF beacon locations to your receive location, and you will get a glimpse of best times for openings to all corners of the world.