47 ms·

Avionics design must be resistant to interference. Unfortunately, perfect resistance is impossible (see GPS and LightSquared). The notion that you should turn

by ISL 14y ago

Avionics design must be resistant to interference. Unfortunately, perfect resistance is impossible (see GPS and LightSquared). The notion that you should turn off "anything with an off switch" as an open-loop solution to the problem is folly. Short of removing the batteries from a device, it's hardly guaranteed that it is truly de-powered. Furthermore, plenty of things don't have an off switch. Pebble watches run via Bluetooth. I doubt users think to turn them off. It's not an easy problem. Sealing the passenger cabin into a Faraday cage may be the only way to ensure RF isolation of instrumentation.

josh2600 14y ago
/Begin Tangent On the subject of LightSquared, I know quite a few people who belonged to that project and I think there's a lot more going on there than meets the eye. In the days following the DoD test for GPS there were a lot of outcries of fraudulent testing parameters that got thrown around and were never really resolved to anyones satisfaction. I still contend that low-orbit satellites can provide a potent and real alternative to the wireless systems we have today (or at least as a distribution path for backhaul). I'm still quite hopeful that the LightSquared kids will get a spectrum swap now that Obama has been settled in the office for a while. Here's hoping; it would be a net-boon for the whole wireless industry. /End Tangent
duaneb 14y ago
Why isn't the passenger cabin sealed into a faraday cage? I would think that would have been the first thing they would build into a plane once devices that broadcast RF became common. I also am quite bad at classical physics, so I don't know the limitations of such a cage.
- genericresponse 14y ago
  Nope, there are windows. That's why your microwave has that grid-looking stuff over the windows. It keeps the cage intact and avoids cooking your eyeballs when you look in.
  - duaneb 14y ago
    Well I'd be happy to sacrifice a few inches of cloud visibility so I could plug myself in to music and turn off the rest of the plane.
fnordfnordfnord 14y ago
The passenger cabin is already a pretty good approximation of a Faraday cage. As far as aircraft GPS go, their antenna is on the outside of the fuselage, top, (because it wouldn't receive a signal on the inside) and connected to the GPS receiver with a shielded coaxial cable. So, I'm not buying any of this nonsense about cell phones and readers and video games mucking up the GPS.

by ISL 14y ago

josh2600 14y ago

/Begin Tangent On the subject of LightSquared, I know quite a few people who belonged to that project and I think there's a lot more going on there than meets the eye. In the days following the DoD test for GPS there were a lot of outcries of fraudulent testing parameters that got thrown around and were never really resolved to anyones satisfaction. I still contend that low-orbit satellites can provide a potent and real alternative to the wireless systems we have today (or at least as a distribution path for backhaul). I'm still quite hopeful that the LightSquared kids will get a spectrum swap now that Obama has been settled in the office for a while. Here's hoping; it would be a net-boon for the whole wireless industry. /End Tangent

duaneb 14y ago

Why isn't the passenger cabin sealed into a faraday cage? I would think that would have been the first thing they would build into a plane once devices that broadcast RF became common. I also am quite bad at classical physics, so I don't know the limitations of such a cage.

genericresponse 14y ago
Nope, there are windows. That's why your microwave has that grid-looking stuff over the windows. It keeps the cage intact and avoids cooking your eyeballs when you look in.
- duaneb 14y ago
  Well I'd be happy to sacrifice a few inches of cloud visibility so I could plug myself in to music and turn off the rest of the plane.

fnordfnordfnord 14y ago

The passenger cabin is already a pretty good approximation of a Faraday cage. As far as aircraft GPS go, their antenna is on the outside of the fuselage, top, (because it wouldn't receive a signal on the inside) and connected to the GPS receiver with a shielded coaxial cable. So, I'm not buying any of this nonsense about cell phones and readers and video games mucking up the GPS.