3 ms·
> Remember that EM fields are subject to inverse-square law. Not inside a metal tube, they're not. This is not to say that I'm a "believer" one way or the oth
by marshray 15y ago
> Remember that EM fields are subject to inverse-square law.
Not inside a metal tube, they're not.
This is not to say that I'm a "believer" one way or the other, but you should also think about it in comparison to the signals that the navigation equipment is trying to receive with its omnidirectional antenna. I.e., a strong CB radio 26,000 miles away. It wouldn't take any power at all to interfere with it, if the interfering signal were on the magic frequencies (which are continually changing due to doppler effects).
- seer 15y agoO
- mikeash 15y ago"which are continually changing due to doppler effects" Doppler effects will be extremely small, since the greatest speed differential you'll see will be twice the speed of an airplane (when two planes are moving directly towards or away each other), which is not a substantial fraction of the speed of light. There will be some shift, but not nearly enough to bump a device from non-interference to interference. Or did I misunderstand something?
- gnaffle 15y agoIt might be that he is referring to Doppler VOR (http://en.wikipedia.org/wiki/VHF_omnidirectional_range http://en.wikipedia.org/wiki/VHF_omnidirectional_range), although I'm not sure how this effects interference scenarios.
- mikeash 15y agoInterference wouldn't alter the doppler effect, though, it would just very slightly change the frequency that would be interfered with. In any case, I don't think any airliner flying today is relying on VOR.