Renowned Pentagon crazytech agency DARPA, which normally wouldn't touch a piece of low-hanging fruit with a bargepole, has announced a new plan which seems strangely practical and achievable. The idea is to develop a backup for satnav location systems using radio "signals of opportunity". DARPA refers to the plan as "Robust …
Sounds feasible, but...
I assume they want to use it in a warzone?
Not too many WiFi hot-spots there, particularly if the power grid is taken out(which is a popular target anyway... )
Again, if the grid is out, these have a battery to keep them operating for a while, but only for a day or so. (Large towers may have up to 3 days. But I doubt you'd find those inside a city)
And when fighting inside a city, you really want better acuracy than 'somewhere close to street X', particularly if you're taking enemy fire or yelling for a medevac...
The interesting thing about BT is that while it has a relatively short range(so that if you can locate one, you know you're close to its position) it's also primarily used in portable devices, so that you can't really be certain about its position.
That leaves setting up your own beacons.
They could set up ground-based GPS beacons(used for differential GPS, I believe?), but that would allow the enemy to also use them.
(Of course, the enemy may have local knowledge of the area and won't need GPS)
Mine's the jacket with a 1:50.000 map stuffed into a pocket.
Sounds really useful
But I can see it getting quite complicated quite quickly; presumably different sources will have to be assigned a weighting in determining where one is, and that kind of thing.
Can II have the $22m please?
OK what's really needed here?
GPS - check
Cell Tower Triangulation - check
Digital Compass - check
Accelerometers - check
All of these technologies combined do exactly what DARPA's after... can I lend them an iphone or a g-phone and pocket the $22m ????
methinks there's more to it
Perhaps they could be vying to make this more clever, such as getting a fix on other radio signals *before*, and as you move, you can get enough points to plot a location for that [generic] radio source. Then your device maintains a local database of these, and (presuming non-flat terrain) can get a 3D position of you relative to it.
Presumably sensible enough to recognise a signal that is mobile, but then you enter a 'canyon', and have built up a database of known points and a known position beforehand, and can work out the positions of *new* signals relative to the other signals. That means you could enter a really large GPS dead area (but signal rich), and then keep knowing where you all the while. That would be immensely useful and impressive.
That leaves setting up your own beacons.
On say an AWACs or similar long duration high altitude aircraft (or High altitude mylar balloon shh..)? assuming the beacon transmits its own Position from its uninterrupted sat fix...
adding to Trygve Henriksen's comments
I thought 'enemy' communication towers/masts/stations were a key target in the early stages of a conflict?
Despite the 'snigger at DARPA propellerheads' angle to this, you would like to think that they have considered this.
Unless they're gearing up for a conflict in a tech rich environment, i.e. Europe which has plenty of RF traffic. - Are the Russians coming again?
So your "modern smartphone - equipped with GPS, WiFi, cell and Bluetooth radios" can tell you precisely where you are to the resolution required to ensure an air strike hits a nearby target and doesn't land on your own head? In the middle of Afghanistan? A rainforrest? Antarctica?
No, thought not.
What's been missed...
....off the spec is the requirement to have the system mounted on a surveillance cockroach with full audio and video feed.
Mines the one being held by the fifth element.
Bah, you're clearly amateurs!
Have faith in the gadgetty goodness- it's DARPA. It'll also do localised location-finding based on the RF signature of the static discharges from soldiers uniforms while marching or the EM hum of power cables in buildings. Or navigation by lightning strikes, the EMP from a distant nuclear strike or even radio comms from the strongest enemy signals (presumably fairly static bases).
It could even work from more powerful satellite signals.
Also, using DGPS style beacons (mounted on supersonic SCRAM-jet equipped, AI controlled UAVs) is a possibility- and interception isn't a problem as the actual correction data provided could be encrypted. They could still navigate based on the beacons signals, but you'd just have to modulate the power outputs in a semi-random fashion to make this pretty much useless (they could get bearings but not location relative to the beacons).
Suddenly, $22Mn doesn't sound like a huge budget...
"i.e. Europe which has plenty of RF traffic. - Are the Russians coming again?"
I doubt it, but who's to say that DARPA aren't thinking in terms of a future conflict with the EU? After all the US use to wargame conflicts with Britain (in Canada and the Caribbean) right up to WW2.
Triangulating in a hall of silent echoes...
"a backup for satnav location systems using radio "signals of opportunity"."
Sounds great. What could go wrong, after all one of the primary targets is to take down all communications in the city, so the enemy cannot coordinate counter attacks. That means there won't be many signals of opportunity left standing after the first wave of attacks!
Add to this, even if a few transmitters survive being initial primary targets, they will still get silenced by the loss of power generation targets.
Oh and if that isn't a big enough problem, they will find navigation via radio signals in a built up area really fun as Steel reinforced buildings distort and reflect radio transmissions like a hall of echoes. No problem if all you want to do is listen to the radio, but big problem if you are attempting to triangulate and/or time signal sources.
Harder then it sounds
It's a bit more complicated then the article suggests, but should be possible.
EPLRS, for example, does most of this. Think of it as a data communications network that also provides you relative position information and has the capability to add a PLGR (Military GPS) or other position location information. When enough stations know where they are, suddenly the whole network can provide absolute position information as well.
The tricky part is to be able to dynamically assign beacon status to emitters not part of the network- For example, a TV tower. First, you have to identify the location of the tower itself. DF gear would make this much easier, but that's generally not included in stock commo equipment. You could play some tricks with signal strength from multiple receivers. Or you could allow operators to manually assign location and approximate signal strength.
Next, you need to be able to calculate location from the beacon. EPLRS uses time to detirmine distance, and I guess if the beacon varies in some manner (As a TV Broadcast would) you could play some tricks and do something similiar- But then you would require contact with your data network to make use of the position data provided by the non-network sources. It's still better then the current solution, as if you currently have direct contact with only 1 or 2 remote stations, you can't calculate position information.
Signal Strength would require contact with the network for initial setup of the beacon, but not afterwards. However, various terrain irregularities could case a "spoofing" effect, under precisely the same conditions as you would need to use it. Trees, buildings, cliffs, etc, could all cause either loss of strength, or create reflections that apparently increase signal strength.
Again, DF gear would seem the best solution (if you have to use non-system transmitters).
Even better might be integrating an EPLRS-style system, military grade GPS, and inertial. As I recall, HTU equiped Avengers (as an example) have all 3 systems, but gunners and slew-to-cue only make use of GPS and inertial, while the TOC receives information from the GPS and EPLRS systems. Scrap the whole nutjob use TV stations as GPS Locations (Like there is really an accurate database of MAC/Location information in a war zone, Lewis?), or just pay it lip service, add an extra ADDSI connector to existing equipment (Or an ADDSI hub device), update some firmware, and win.
Spend the rest of the cash on helicopters.
that's a relief
After all that crazy weirdness like ARPANET.
If their software is remotely like the software for the company I work for, it should be easy to determine where the radio sources are, in spite of the reflected signals. We ship our software out on every audio unit. It uses stereo mics to listen to the sound, then the software models the environment and corrects for obstacles/materials by changing the sound output from the speakers to image correctly. If we can do this for less than a hundred dollars per unit, why couldn't DARPA?
Wigle.net (http://www.wigle.net) has a large database of European and United States geocoded WIFI access points. Each access point (whether open or secured - both types are in the database) has a GPS lat/long. You can use the data however you wish, including for "assisted GPS" type projects.
This data is FREE to use. You don't have to "pay to play".
I think UK armoured cars do this already
As in cash carrying rather than AFVs.
Rather than dedicated "Beacons" they use one or more stations in (IIRC) the AM bands. Its referred to as "Datatrac."
But as others hae noted this is clearly not up to the bonkers level of DARPA's usual list.
Mine's the one with an old back issue of E&WW in it.
Been there, done that, god the camper van
Me-thinks DARPA should contact Mr Peter Duffet Smith. Who demonstrated on the BBC (~1995) a working 'signals of opportunity' navigation system, built into an old camper van.
This consisted of, 4 wide-band antennas mounted on the corners of the van, a computer controlled scanner with phase comparators and an old, even then, PC.
This device could use any set of transmissions from known fixed sources to locate the vehicle to within 2 meters.
OK job done, time to put the van on ebay under $22m buy it now .
Coincidence? i think not...
Hmm.... so DARPA is developing a system to use when satnav is unavailable, just when there is a report that the GPS network could collapse as soon as 2010. http://www.theregister.co.uk/2009/05/21/gao_predicts_gps_failure/