DIY: Cheap, ultra low-power radios that communicate over thousands of miles

I wonder if this is similar to what Paul Lutus did to communicate from the open seas back to his Oregon home during his sail around the world?<p>Here is an excerpt from his book:<p>My ham radio link is working better than expected. Before I started this sail, I spent some time installing and testing ham radios and computers in both the boat and my house in Oregon. I wanted to be able to write a message here, transmit it by radio, and print it on paper in Oregon. At the Oregon end, because a normal person (not a radio nerd) has to be able to use the system, there's a simple "message screen" on display. A person just sits down at the computer and types a message, then presses a key that saves it. The next time I make contact I collect the messages.<p><a href="http://www.arachnoid.com/sailbook/Chapter_2_--_Oregon_to_Hawaii.html" rel="nofollow">http://www.arachnoid.com/sailbook/Chapter_2_--_Oregon_to_Haw...</a>

It should be noted that he is on the 30m Amateur Radio band. I would not suggest doing this unless you are a licensed ham of general or better.<p>That begs a good question. How many hackers here are also hams? I'm W1OFZ.

Reading this thread is giving me the bug again :-)<p>I might just go into the basement and put together a simple 40 meter receiver tonight just to see if there's any activity there and maybe build a small transmitter later.<p>ISTR that the FCC went to non-expiring licenses. My last one is from the late 80's/early 90's. Anyone know what the likelihood is that I still have a valid license?

3600 miles, 100 milliwatts, 5Hz of spectrum near 10MHz, rooftop mounted dipole, $25 of parts to make radio (including obligatory Altoids tin) =&#62; 0.05 bits per second.<p>[Edit: to lose that extra zero. Thanks Joe.]

hey there i'm kd8mek, i wrote a blog piece about software radios and such the other day <a href="http://verily.posterous.com" rel="nofollow">http://verily.posterous.com</a> there are a billion of these qrp small radio blogs out there, all kind of people dreaming up all kinds of things

While it is interesting I can't really get excited because to me a QSO is a two way conversation. Far more interesting to be running a few watts and be having two way conversations with people instead of being merely captured on their computer screens.

Why do they transmit a square wave, instead of just short and long dashes of a single frequency? Only the top of the square wave is the signal, the bottom is the 'negative' of it.

I wonder if this could be combined with UWB-like principles: you encrypt the clock at both ends and only look at the signal at certain timestamps.

Hmm, interesting.<p>Makes me think about an alternet for when they switch the internet down.