[ltp] Re: Linux-Thinkpad digest, Vol 1 #632 - 27 msgs

[morpheus]

I agree, shut them off during takeoff and landing.
As WAAS (Wide Area Augmentation System) gets phased in, things should
get much safer.  The current system of radio beacons and ILS/DME
transmitters is not optimal.  Transmitters are located at the airport,
where they are susceptible to ground interference due to vehicles moving
around, and their accuracy depends on the receiver in the aircraft being
properly programmed and calibrated with the correct assumptions on
flight characteristics.
My understanding of WAAS is that GPS will be augmented by a network of
ground transmitters that broadcast GPS-like signals, allowing for easier
triangulation and more accurate positioning.  Of course, these still
would be susceptible to interference, but given their geographic
separation, location in remote areas and the redundancy of the
transmitters, it will be much safer than the current system.



On Sun, 2004-10-03 at 10:36, Don Perley wrote:
> >
> >
> >>
> >> Does this make sense to all you experts out there?  Am I finally off the
> >> hook for my tragic "amps" error?
> >
> 
> Sort of.. we now know that it was a limited scope study, with limited 
> scope conclusions.
> 
> Just an example of  unexpected things that can cause interference when 
> you get beyond simple tests..  There is a interference situation on a 
> local mountain top where the best guess is that the signal from an FM 
> radio station and that from a weather radio transmitter are combining in 
> a parasitic diode mixer formed by rusty bolts on a tower and spitting 
> out interference on a 3rd frequency nowhere near the other 2 (but 
> related by a common intermodulation relationship).
> 
> The moral of the story is that when  you get a cabin full of passengers 
> with gadgets spitting out various frequencies even at micro or milliwatt 
> levels, you can get results matching those used by the avionics front 
> end, intermediate frequency, local oscillator, etc.  Antenna cables and 
> other wires  go all over the plane  giving a  path to the cockpit.
> 
> If the end result is a problem with the avionics, it is not going to be 
> a time critical emergency if the plane is on a stable flight path.  On 
> take off or landing you don't have time to deal with it; hence the 
> typical announcement to keep your toys off until the plane gets to 
> 10,000 feet.