Discussion in 'Computer Games and General Discussion' started by Veho, Nov 15, 2008.


by Veho Nov 15, 2008 at 5:38 PM 1,378 Views 4 replies
  1. Veho

    Veho The man who cried "Ni".

    Former Staff
    Apr 4, 2006
    Reasonable Optical Near Joint Access


    [​IMG] [​IMG]

    "Ronja is an open source project for reliable DIY optical data links with a current range of 1.4km and a communication speed of 10Mbps full duplex." All the schematics, guides and tutorials are available on the site.

    Simply put, it's an IR port on steroids. The transmitter is an IR LED, focused through a concave lens, and the receiver is basically a telescope (with a 1 pixel resolution, but hey, nobody's perfect [​IMG] ). You need one of each on both sides, and since both are encased in plastic/metal tubes, the whole setup looks like a dual missile launcher mounted on your balcony (also, cue the "with RONJA, the Internet really is a series of tubes" jokes). The original designs are somewhat exaggerated, to make the setup withstand the elements, pigeons, earthquakes and the occasional meteorite strike, but I'm sure you could tone it down a bit for your personal use.

    The device itself acts like a router. Plugs into either the Ethernet or the USB port, depending on the version. The setup consists of one device at each end, and you need direct line of sight between them, although you can use a mirror to go around corners [​IMG]

    Or, you could set up a repeater/hub at a central location. But be ye warned, down that road madness lies.

  2. FAST6191

    FAST6191 Techromancer

    pip Reporter
    Nov 21, 2005
    United Kingdom
    I have a feeling if I tried such a thing around here I would soon find myself staring down several well armed "police" or more likely enjoying a car ride with a fashionable new hood in fairly short order. Then again as there is a curfew in all but name around here and knowledge makes you a target for the filth (at least they have the right target I suppose).

    Also nice spray paint job on the green wall.

    Back on topic only 10Mbps, I will stick with microwave link or wireless distribution/mesh networks for now.

    Also LEDs, I can understand those over lasers to a limited extent (LEDs are fine but I start firing lasers around and the initial scenario becomes 10x more probable) but noise (IR being emitted by hot objects after all) and extra signal power coupled with a nominally increased tendency to listen in (encryption would be my next query and a casual look around the site has nothing on it, sure I could set up encryption at network level but device level would be nice.
  3. Linkiboy

    Linkiboy GBAtemp Testing Area

    May 14, 2006
    United States
    ...Wouldn't this be really bad for the eyes of people who just happen to be looking at the receiver thing, wondering what it is?
  4. Veho

    Veho The man who cried "Ni".

    Former Staff
    Apr 4, 2006
    Nope, since it's directional, and you'd have to stand somewhere along the beam path to see anything. Merely standing on the street looking up at the array you wouldn't be able to see anything. Besides, the whole setup is very low power (around 10-20 milliWatt), and you could stare directly into the LED with no ill effects.

    @FAST: regarding security... since the transmission is directional, anyone eavesdropping on your communication would have to be either on your balcony, the roof of the building on the receiving end (peeking over the receiver's shoulder, as it were), or intercepting the beam somewhere along its path (hovering in midair). Better focusing would take care of the fact that the beam is over thirty feet wide by the time it reaches the receiver. Narrow it down to a foot or two, and put a black sheet to block the rest of the beam (you could use a laser instead of trying to focus a standard LED, and at shorter ranges a laser pointer will suffice, but then the setup gets extremely sensitive to shaking). Paint the receiver fuzzy matte black, to prevent anyone trying to hunt for reflections, extend the projector and receiver tube a foot or two so that the lens can't be seen from an angle.... there's probably more physical protection stuff, this is all off the top of my head, I can't be arsed to think of anything else right now. Probably enough to protect it from amateurs and script kiddies armed with standard WiFi cards.

    As for encryption on a device level, it can always be added while you build the thing (I'm sure there's room for a few (hundred) more lines of code). Probably safer that way, seeing how the device design and software is open source, and any preset encryption/decryption protocols would be available to anyone.

    That being said, the device as it is now is clearly not for any sort of professional use. Right now it's more suited to connecting to a friend's computer and sharing porn.

    Regarding noise. There's a red LED version as well as an IR one. The signal power level is (probably) higher than the background noise. The device is directional, and "ignores" sources outside its viewing angle. Though there are influences that could garble the connection briefly (lightning for example), but that should only slow the connection down.

    All that remains now is the problem of it looking like either a missile launcher or like a camera aimed at the local kindergarten, both of which implications would drop you headfirst into... trouble.
  5. UltraMagnus

    UltraMagnus hic sunt dracones

    Aug 2, 2007
    I would imagine the LED is a LASER LED, the sort you get in those £1 laser pointers, but in the IR range

    as for eye damage, unless they are using a very powerful LED, it won't do any damage unless you stand right in the path of the beam staring at it for several minutes

    Its nothing really new to be honest
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