from Hacker News

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

by elimisteve on 7/25/10, 8:29 AM with 29 comments

• by euroclydon on 7/25/10, 1:49 PM

  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?

  Here is an excerpt from his book:

  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.

  http://www.arachnoid.com/sailbook/Chapter_2_--_Oregon_to_Haw...

• by joshfinnie on 7/25/10, 3:20 PM

  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.

  That begs a good question. How many hackers here are also hams? I'm W1OFZ.

• by HeyLaughingBoy on 7/25/10, 11:12 PM

  Reading this thread is giving me the bug again :-)

  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.

  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?

• by jws on 7/25/10, 1:13 PM

  3600 miles, 100 milliwatts, 5Hz of spectrum near 10MHz, rooftop mounted dipole, $25 of parts to make radio (including obligatory Altoids tin) => 0.05 bits per second.

  [Edit: to lose that extra zero. Thanks Joe.]

• by th0ma5 on 7/25/10, 7:33 PM

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

• by rmason on 7/25/10, 5:44 PM

  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.

• by Luc on 7/25/10, 10:52 AM

  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.

• by joshu on 7/26/10, 4:22 AM

  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.

• by Kilimanjaro on 7/25/10, 5:41 PM

  Hmm, interesting.

  Makes me think about an alternet for when they switch the internet down.