Sunday, April 16, 2006

Ham Radios, Coding Theory and the Internet

Venkat Guruswami talked at TTI last week giving an overview of recent work in list decoding. Someone asked him about practical applications of his work and he mentioned ham radio operators now able to error-correct signals bounced off the moon.

My memories of ham radio go back to summer camp. As one of the activities, we could go to a trailer with the Ham Radio Guy (who looked something like this) and we would try, not always successfully, to reach other ham radio operators around the world using Morse code and occasionally voice. Plastered around the trailer were postcards from other ham radio geeks he did talk to.

Ham radio was sort of a precursor to the Internet, which begs the question—Why hasn't the Internet made ham radio obsolete? You get much better bandwidth over TCP/IP than bouncing signals off the moon and you don't need a license to use the Internet.


  1. Why did he mention ham radio, and not the much more important application of 802.11? Is there something about 802.11 which makes it inapplicable? My understanding is that it should allow for a straightforward swap-in (aside from error correction generally being done in hardware) and produce a side-effect-free positive result.

  2. But for all intents and purposes, ham radio is obsolete.

    That a few people are still using it today is due to what you could call the Renaissance Faire effect.

  3. Ham radio remains useful as a backup communications medium in emergencies where other media with greater infrastructure requirements are not functioning.

    It's been widely used in various natural disasters in the past decade.

  4. These days, kids should never go into a trailer with the ham radio guy.

  5. As well as the renaissance-faire effect (such as the people running WW2 Hellschreiber kit), there's also still interesting new technical stuff that radio hams can do -- for example, there are several amateur TV groups in the UK that are running their own (legal) terrestrial digital TV services using DVB-S rather than DVB-T. There's also the usual degree of fun in doing stuff for yourself.

  6. Will the Internet make ham radio obsolete?

    Heck, we think ham radio will make the Internet obsolete! Specifically, the GNU Radio Project, which we use in our end-to-end quantum simulations when we want volts, not pictures.

    GNU Radio Home Page

    GNU Radio on OS X

  7. Why hasn't the internet replaced ham radio? May as well ask why it hasn't replaced the telephone which is even older. We still send faxes and that is WW2 technology. Amateur packet radio (w/ error correction) was a precursor to the internet. Bouncing signals off the moon isn�t new either. Packet radio is only a very small part of ham radio. There are still parts of the RF spectrum that the knowledgeable ham may experiment with and have much greater bandwidth than available via the internet. Internet service is also dependant upon several entities whereas the ham operator is dependant on his/herself and can play radio anywhere. Disconnect the phone lines, cable systems, OC3�s or power companies and there is no internet. Ham radio still works. Remember also that ham radio is an emergency service because each station is a stand alone entity. I will say that many hams today in this country aren�t too technically skilled or intelligent, perhaps even half of about 700K. That�s 350K who still were at least smart enough to get licensed. How many people turned to the internet instead? Oh, we hams are already licensed to use 2.4GHz at much higher power levels than can be achieved with standard 802.11 gear.

  8. In Body of Secrets, Bamford describes how a US spy ship used radio (?) signals bouncing off the moon to send intercepted communications home to the NSA. This was as early as 1962, I believe.

  9. Ham radio cannot be obsoleted.

    It is unique. There is no infrastructure-free long distance communications mode aside from propagating a radio signal using something naturally occuring, whether that be ionospheric or moon reflection , or ducting in the troposphere, or something else.

    The only way an average person not affiliated with a specific government or private radio service has access to the radio waves is via ham radio.

    I also think asking why the internet has not succeeded in obsoleting ham radio is like asking why email hasn't obsoleted stamp collecting. It's impossible to render a hobby obsolete.

    There is a larger percentage of the U.S. population licensed as radio amateurs now than ever before.

    That percentage is 0.24%

    There has never been a time when ham radio was used like the internet, by a majority of people for routine communication. At the heyday of radiotelegraphy, the routine communication was handled by paid professionals! Landline telegraphy and telephone also existed and were reliable.

    I think that the ham radio hobby may possibly be considered a precursor to the internet HOBBY.

    The "ham radio operators" of the internet are those who enjoy pushing the limits of content delivery on the web, page design, or their hardware. This is a tiny percentage of internet users.

    I think the morse code and large, heavy, old tube radios make it seem like ham radio *should* be obsolete, and technology-wise they are.

    But my radio has microprocessor control of almost all operating parameters, digital signal processing, covers almost all of the popular ham bands and is about 6 inches x 2 inches x 9 inches.

    I sat down this morning with my coffee and contacted a guy named Ilshat in Siberia using just my radio, 20W of power, and 100 feet of wire so fine as to be practically invisible from the ground. We used morse code. You just have to have the radio bug to get it.

  10. I need internet communications out in the middle of the Central Pacific Ocean where I will be coconut reforesting for the next 14 years. Is it possible to link throught the ham satellite?