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Ask Eric Blossom about Software-Defined Radio

Posted by michael on from the modern-crystal-radio dept.

Eric Blossom is an electrical engineer with a history of working with radio and communications security. He gave a presentation at the recent H2K2 conference about his work with GNU Radio, which is, bar none, the single most exciting software project in existence today. (Imagine computing devices that communicate seamlessly across the entire electromagnetic spectrum.) As usual, we'll forward some of the best questions to Eric and post his responses when we receive them.

3 of 181 comments (clear)

  1. Hardware requirements by wowbagger · · Score: 5, Interesting
    The GNU radio page is a little thin on the hardware requirements to run the code - could you spell them out?

    I realize this might be complex, and that the answer might be of the form

    to demodulate a 16QAM signal at 115.2kBaud, you would need an XYZ digitizer card reading the 455 kHz IF and a AAA GHz Athlon CPU. To recover standard multplex FM, you would need a 123 digitizer reading the 455 kHz IF and a BBB GHz Athlon. To decode GSM you need a FFF digitizer reading the 10.7 MHz IF and a quad Athlon.


    But as both a ham and one who designs SDRs, I'd like to know where this resides on the Home Hacking Scale....
    --
    www.eFax.com are spammers
  2. Re:FCC vs. Software Radio by killthiskid · · Score: 5, Interesting

    I'm thought something along the same lines... used to be that any RF that came into a person's airspace was fair game... now that's not true. It can be illegal just to 'listen in' (esp. if it involves decrypting the signal).

    It seems to me we're moving the complexity away from expense to duplicate hardware into 'free' to duplicate software. With the increase in power and decrease in cost of general purpose (programable) electronics (i.e. CPU, radio recievers, ADCs, etc), one person can write complex software that can then be used to utilize the (relativiely) inexpensive hardware.

    Once you have the hardware setup, you can change the software and:

    • Listen to police band.
    • Listen to cell phone.
    • Listen to XM radio
    • Listen to satelite transmissions
    • Listen to military communications?
  3. Some explanation of what can be done with this by eyefish · · Score: 5, Interesting

    After reading some posts, some people seem to be a bit confused as to what this is and how it can be used. Well, for the /. crowd, here's a specific example which will put all this into perspective:

    Now that generating waves becomes a software problem, it means that theoretically anything that before needed hardware to modulate/demodulate (or encode/decode, depending how you look at it) signals can now be done in software. Practially, this means that you can transform your machine into a WiFi or Bluetooth system by simply installing the right software. It also means that as new future wireless technologies emerge, your hardware can support them by a simple software install.

    Similarly, anything that uses radio waves can be "emulated", like a good old FM/AM radio (the website has sample code for this), a Walky-Talkie, a home wireless phone, or even a cell phone!!!

    So now you see why there's a lot of exitement around this. If the project could only get more funding (Intel? AMD? IBM? Sun? Motorolla? Sony?) to speed this up...