• Ephera@lemmy.ml
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    10 months ago

    I could imagine that those concave metal roof sheets reflect the electromagnetic waves all over the place, causing tons of interference…

    • CanadaPlus@lemmy.sdf.org
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      10 months ago

      Are they not equipped to deal with that? You’d think large metal surfaces are pretty common, so it’d be a bigger issue if so.

      • Ephera@lemmy.ml
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        9 months ago

        Well, straight metal surfaces are a whole different story from concave metal surfaces.
        The former causes interference in a line in one specific direction, with roughly the width and height of said metal surface.
        Concave metal surfaces on the other hand, can easily blast a whole room, depending on how concave they are.

        And I’m a bit out of my water here, but I believe, modern WiFi does try to

        1. direct its EM-waves towards the recipient, rather than send in all directions.
        2. adjust the strength of its signal, so that it reaches the specific recipient and not that much more beyond that.
        3. resolve multipath issues, so where a recipient can be reached in two or more ways, e.g. directly and through a reflecting metal surface. It can attempt to do so with 1) and 2).

        But yeah, ultimately this can’t be an exact science. Recipients move around. Interferences move around. You still need additional EM-waves to advertise yourself as WiFi to disconnected devices. A reflecting interference may be situated behind a recipient, where you do need to send signals to.

        And of course, no one expects the Spanish Inquisition Google’s house of mirrors, where any misdirected EM-wave will interfere with everything else in the room. That just ramps up any imperfections in WiFi by a lot…

        • CanadaPlus@lemmy.sdf.org
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          9 months ago

          This design looks like you could get more than one roof segment involved, too, especially if there’s a lot of traffic. I didn’t know that they actually manage spacial relationships like that, but I guess it makes sense. I suppose that’s why the extra antennas on some models.

          In theory, a radio reflection off something non-flat can be a treated a bit like an extra point source. My curved tea kettle won’t mess with wi-fi, because a reflection off it just looks like a straight but lossy path that’s the sum of the distances involved. If something’s a wavelength across weirder things can happen, of course, but wi-fi is in relatively short bands for the most part, and there’s more than one so it can just switch if it’s in a dead spot. A wi-fi signal will also be modulated pretty fast, though, so now you have to think in frequency space as well, I’m not sure how that works.

          Google’s hipster building is on a scale that’s very different from a kettle, but at least as complex geometrically, so maybe that’s where the gap in access point design lies. They expect small distortions and big perfect reflections.