Weather Fax using an iPad and a $135 radio

Continuing on the theme of offshore communications, I thought I'd muck about with my iPad and a cheap shortwave radio, to see how easy it is to receive weather maps. The short answer: easy when there's a signal, but signals are hard to find, much of the time. I had trouble at any time of the day getting ANY signal that sounded even remotely like HF Weather Fax. Still, when I finally found one, turning it into a weather map was easy. Perhaps a better radio or antenna would make lighter work of finding a signal. I bought a fairly cheap but well regarded shortwave radio, just to play with at home, so hopefully a proper marine SSB set would be a lot better! I've always been a radio nut, for unknown reasons, and living in Honolulu one is literally in the middle of nowhere, so it will go into our emergency kit once I've finished playing.

I already have an iPad, and bought a $2.99 piece of software for it from the App Store called HF Weather Fax, by Black Cat Systems. As with all iPad software, installing it was a piece of cake, taking about 1 minute. This software listens through the iPad's built-in microphone, to the output from an ordinary HF radio with SSB (single-sideband) capability. When tuned to a station that is sending out weather faxes, the application will display the faxes on the iPad's screen.

But as mentioned in previous posts, how well would it work in practice. The early results are in, and it works just as advertised WHEN A SIGNAL IS PRESENT. Unfortunately, this doesn't seem to be all the time, and in fact it took me a couple of hours of listening over the last several days to get a signal at all! The software has a built-in schedule from NOAA of broadcast times and frequencies, and it reminds the user to tune the radio to about 2 Hertz below the carrier frequency. I'm not sure why this is, but it was easy to do. The schedule said that Honolulu would broadcast all day long on 11090, so I tuned the radio to 11088. I also set the radio up to listen to "Upper Sideband". Even though I'm a ham radio operator from way back when, I honestly can't remember why it's necessary to detune, and I'm also a little fuzzy on USB/LSB.

I followed the directions, but initially got nothing. Then I waited for a while, and eventually got a signal. I remember from my HAM radio days that SSB radio "comes and goes" as atmospheric conditions change, so I wasn't really put-off by the initial lack of success. Here's an example of the system receiving a NOAA weather fax while sitting next to the radio. Note: no wires -- I think it would likely work even better with some sort of speaker-to-mic cable between the radio and iPad, but it works just fine this way. The only downside is that each fax takes several minutes to come through, so you have to listen to the somewhat annoying noise if you don't have such a cable.

Just to be completely 100% clear, the picture you see on the iPad came completely from the Sony HF radio, not over the Internet. Despite all the difficulty I had acquiring a signal, in the end I felt this was pretty cool!

For the radio, I bought a Sony ICF-SW7600GR, as pictured here. It cost me about $135 online through I selected it because it had a very good reputation online. It is easy to use, compact, and has a "quality" feeling about it. It is made in Japan.

I was probably less than 100 miles from the transmitting station, so this was not really a fair test of offshore performance. I will attempt to tune in a further-away station at some point, and will append to this blog entry once I've done so. Over the past hour, however, I tuned every single frequency included in the guide, worldwide (about 50 total). I only found two signals, and of those, only one sounded like weather fax (it was from my local Honolulu NOAA station). Once I had a signal, getting a map was easy. But getting a signal -- that turned out to be hard, or at least frustrating.

For now, I can say this: With an HF radio and an iPad, if you can find the signal, you can get the weather map. But if, out at sea, it turns out to be as hard to grab a signal as it was for me over the past few days, let's just say that BGAN or Mini-VSAT are looking pretty good!


Winter 2011: Training from Lauderdale to Georgetown and back!