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WEATHER RADIO

Weather FAX on the Cheap By Gary Jensen

W

ith the 2005 hurricane season here again, up-to-date weather maps and forecasts are critical to the safety of offshore and coastal voyaging. You can receive these forecasts while at sea using readily available, moderately priced equipment. You don’t need to have a dedicated Weather FAX (WEFAX) machine on board, nor is it necessary to use a new sophisticated marine SSB. In many cases, you already own one or more of the components needed to create a WEFAX system. Basic WEFAX System Architecture A basic WEFAX system consists of a radio capable of tuning to the WEFAX frequencies (See Table 1), a computer, some software, and an audio cable to connect the radio and the computer together. Audio from a radio is fed into the MIC connector on the computer sound card, where a program tells the computer’s sound card how to decode the signal, and store, print, or display the results on the computer screen. The Radio Your choice of radio is limited primarily by how much money is budgeted for its purchase. While new radios like the Icom M-802 marine SSB or Icom 706MKIIG ham radio are ideal, older marine radios like the Kenwood TMK-700 or Icom M-700 (not to be confused with the M-700Pro), or older ham radios like the Icom 735 or Kenwood TS-440 will work just fine. Even inexpensive general coverage shortwave radios from companies like Saegean, Sony, and Grundig, can be made to work, although the lower-cost models do not provide as good a result as do the more expensive models. If you are planning on buying a used radio, the three important features you are looking for are: Frequency stability. The radio must stay on the frequency to which it is tuned. Any up or down frequency drift will cause the WEFAX output to shift lighter or darker, making the received document difficult to read. The ability to “fine tune” the radio. To receive a readable WEFAX document the radio must be able to accurately tune in a signal to 100-

hertz accuracy. For example, to receive WEFAX documents from the Boston station NMF, the radio must be tuned to 9108.1 kHz. The number to the right of the decimal point is tenths of a kilohertz, which in this example equals one hundred hertz. The ability to reject adjacent signals. A good radio has the ability to reject interference from other stations broadcasting on nearby frequencies. The better job the radio does in separating the signal you are trying to tune in from adjacent signal interference, the clearer your WEFAX document will be. These important features come at a price, and they’re what differentiate a $2000 - $3000 radio from an $80 - $200 radio. Does this mean that you must spend thousands of dollars to get a radio that will produce the satisfactory WEFAX results that you want? No, not at all. As cruisers and hams update their radios with newer, more feature-laden radios, their used equipment frequently ends up on the used radio equipment market. Used marine radios in good condition from Icom and Kenwood can be bought for several hundred dollars, a fraction of their price when new. If you are in the market to buy a used radio and don’t know where to begin looking for one, you might start by asking the folks around the docks if they know of anyone selling a used radio. Other resources to check are dealers like Amateur Electronic Supply (www.aesham.com), and Ham Radio Outlet (www.hamradio.com), ham radio clubs in your area, and, of course, the listings on e-Bay. With a little diligence, for $300 - $400 you should be able to find a radio that will tune in WEFAX, and with the appropriate FCC licenses, lets you talk on the ham or marine frequencies. The Computer WEFAX technology was perfected during the 1940s, so you don’t need the latest and fastest computer to decode it. Just about any Pentium/AMD-based computer with a 16-bit or greater sound card, and Windows 98SE or later, should work just fine. The sound card is a requirement because the software will use it as a “radio modem.” That’s right; there’s no need to buy a separate “radio modem” or use a separate decoding module to decode the WEFAX signal. A computer and radio are the only hardware components needed. The Software There is a variety of freeware, shareware, and commercial software in the market that will decode, store, display, and print WEFAX documents. The cost of these programs ranges from free, to several hundreds of dollars. One of the more popular programs is the shareware program JVCOMM32. Written by Eberhard Backeshoff in Germany, JVCOMM32 can receive maps and forecasts broadcast on the HF (High Frequency) bands, and directly from low earth-orbiting (LEO) satellites like METEOSAT (if you have a satellite receiver and antenna). JVCOMM32 will also copy

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September 2005

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