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Global Positioning Without GPS
GadgetMike sends word of an award to Boeing for work on a Robust Positioning System that could make use of cell signals, television transmissions, and other clues to provide position information when GPS is unavailable. (Wonder if they've heard about Skyhook Wireless, which does a similar job based on Wi-Fi hotspots, for 2500 US cities and towns.) The work is being sponsored by the US military, so it's not surprising that they don't want to rely on upcoming GPS enhancers or replacements from France, China, and Russia. Here is the Boeing press release.
Pilots have used VOR http://en.wikipedia.org/wiki/VHF_omnidirectional_r ange for a long time. Knowing the lat/lon position of other radio beacons and being able to detect them is (IIRC) something that was experimented with for robotic vehicles.
Using geo-data and good state of the art receivers, it would be possible to locate your position reasonably accurately if you have many landmark transmitting beacons. The trouble is making those receivers small enough to be useful. Of course, this might not work too well in the middle of a desert but would function well enough for many problems.
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Robust navigation? From a jumble of tv/mobile signals? I don't think so. For absolute position VOR+DME is pretty good and ILS/MLS around terminal areas. Relative collision avoidance is handled by S-mode transponders and TCAS.
Use existing systems. ATC could gather all the TCAS negotiation information via the s-mode datalinks and use that to make a more accurate picture of the traffic than the survaillance radar alone can provide and broadcast that back to the planes. All that the planes really need anyway is their relative position to other planes more accurately. Absolute geographic position is accurate enough with the existing systems for purpose of terminal procedures and terrain avoidance.
Then again I think we should develop the reliability of GPS satellite constellation and adding Galileo to that will make it very robust with dual receivers and multiple antennas on the planes. To make ADS work will need dependable GPS type vector information anyway...
We've had http://en.wikipedia.org/wiki/LORAN since WWII. It works fairly well for ships and airplanes, I'm sure it will be quite enough to guide airplanes to nearest aerodrome in case of aliens knocking off GPS satellites.
An excellent point when considering developed countries.
What about use in Afghanistan, though? Even Iraq in the months directly following the invasion when power and basic utilities were scarce? The number of measurable signals would have been cut harshly and the ability to confuse such a system would have increased.
I have no doubt about the viability of the signal/location system in good circumstances. I remember navigating on flight-sims using the system.
I am worried about more military money going into a system that assumes even a reasonable level of infrastructure stability to operate. Adding to that, I am concerned about all of the military's pet projects.. the failure of an initiative (ie. the Osprey project which has killed many servicemen and is now being deployed in combat situations) only justifies further spending, not review of standards and procedures.
Maybe I am dissillusioned, but I don't see this working in ultra-harsh conditions. Sattelites seem safer.
To be precise, the Blackbird used an astro-inertial navigation system originally developed for the Skybolt missile. This used the position of the sun or other selected stars to refine the position estimates given by the inertial nav system. A related guidance system is used in the Trident II missile.
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Oh come now, You must be referring to Galileo system that is being buid for the EU and ESA (European Space Agency) by European Satellite Navigation Industries. So it's basicly european system not French. Get your facts straight.
More on subject:
The EU site for the Galileo project http://ec.europa.eu/dgs/energy_transport/galileo/
The wikipedia site: http://en.wikipedia.org/wiki/Galileo_positioning_