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NAVSOP Navigation System Rivals GPS
dangle writes "BAE Systems has developed a positioning solution that it claims will work even when GPS is unavailable. Its strategy is to use the collection of radio frequency signals from TV, radio and cellphone masts, even WiFi routers, to deduce a position. BAE's answer is dubbed Navigation via Signals of Opportunity (NAVSOP). It interrogates the airwaves for the ID and signal strength of local digital TV and radio signals, plus air traffic control radars, with finer grained adjustments coming from cellphone masts and WiFi routers. In any given area, the TV, radio, cellphone and radar signals tend to be at constant frequencies and power levels as they are are heavily regulated — so positions could be calculated from them. "The real beauty of NAVSOP is that the infrastructure required to make it work is already in place," says a BAE spokesman — and "software defined radio" microchips that run NAVSOP routines can easily be integrated into existing satnavs. The firm believes the technology could also work in urban concrete canyons where GPS signals cannot currently reach."
If its just using signal streangth then there are going to spots in cities or other cluttered terrain where it could be innaccurate. It would be ok if there is no terrain to interfere.
Google has been using this for some time and is used on Android devices - you can see their patent here: http://www.google.com/patents/US7532158
A-GPS is not new (http://en.wikipedia.org/wiki/Assisted_GPS), though they seem to want to extend it to other radio sources.
Never happened. True story.
Sure in an open area the signal strength from broadcast and third-party location services is fine but so is GPS.
But in an urban environment these are not accurate signal strength is only loosely proportional to inverse square of the distance so any accuracy will utterly break down. I can't see them having the money investing on getting a location DB for coverage outside major cities meaning you have to ship an unusable feature to most of the population.
The firm believes the technology could also work in urban concrete canyons where GPS signals cannot currently reach.
This will only work by regularly updating a database of local signals by driving down these roads and walking around areas. You might get the reliability for a consumer device but SDR like this can hardly be cheap, small and low power.
Possibly they have algorithm to make this manageable but i would think installing purpose built transmitting devices at every street corner would be a better option.
While it sounds like this would work decently well in cities, it probably won't have nearly as many signals to work with in less populated areas, and it would be practically useless out in, say, the middle of the Pacific. So at best, it's a complement to GPS, not a replacement.
Second, how is it going to match up different sources with physical locations? I assume they'll just have a massive database of "this wifi router is located at 31.41592N 27.18281W, this AM transmitter is at....", but that brings up even more problems. Who will maintain that database - the big regulated transmitters can probably be figured out easily, but WiFi routers? How much space will that DB take up - could make it prohibitive on some devices?
It interrogates the airwaves for the ID and signal strength of local digital TV and radio signals,
So let me drive 3 hours north of Perth, Western Australia and find that this system is as useful as an ashtray on a motorbike.
I cant really see a use for this technology that GPS doesn't already fill and a huge drawback because as soon as you get to places with only one mobile phone tower or one source of TV signals (most rural towns in Oz) its fucked (the fewer sources you have for triangulation, the less accurate the result). Then we have the great wide expanse between towns which can get up to 500 KM of open road with no TV, no mobile coverage, no WiFi networks and even AM radio is spotty at best. In fact in many places the only source of radio transmissions will be from 2 way radios mounted on trucks... if there happen to be any trucks in the area.
Really this is some nice research BAe but it has no practical use outside the lab. Seeing as it's only useful within cities any commercial product will remain inferior to traditional GPS.
Calling someone a "hater" only means you can not rationally rebut their argument.
Because we all know how reliable & accurate cell tower triangulation is. That's why wireless phone's all have A-GPS being built-in, because the networks accuracy was at best a few blocks, which the FCC considered unacceptable for the nation's 911 systems. WiFi systems have such a long signal reach, many miles no doubt. Radio stations always broadcast as exectky the same power, which is why somedays you can hear them much better than others. I doubt that this will be long lived
Cheers !
This isn't really a new concept. Rosum was doing this years ago, calling it RadioCamera. They used GPS to record a broad range of signals, including reflections, and map them out. Using that data they built a map that could be used to locate a receiver.
http://www.prnewswire.com/news-releases/trimble-and-rosum-team-to-develop-universal-positioning-technology-74497582.html
When Rosum liquidated it's assets they were bought by TruePosition: http://www.trueposition.com/technology/
One interesting challenge not mentioned in the description of BAE's system is how they create the map. GPS has relatively few satellites and they broadcast their positions which is used by a receiver to determine it's own position. Relying on other radio sources will mean having them all mapped. Either the receiver needs knowledge of all of these ( unlikely) or it gets updates for it's local area periodically over a data channel. The map is also likely to be more than just an antenna's location, but data as to how it's received based on local topography. Alternatively it could send a snapshot of what radio signals it receives and the position is actually determined back at a server and relayed back to it. Either way seems to presume a separate data connection to the receiver to either load the whole database of signals sources ( and update it ) or a continuous connection to get the local database as it goes.
Using other signals of opportunity would be a good way to augment GPS, but surely not a replacement. Not being a replacement, I'd have a hard time calling it a rival.
I used to work for a subsidiary of TruePosition. One of the ventures they worked with developed this technology several years ago. It used the timing differences in the TV signals to ascertain position. TP acquired interest in that it provided the ability to obtain a location in areas where GPS sucks - like downtown Manhattan or other dense cities. Using external positioning devices, this technology could also provided high accuracy positioning within buildings - including altitude.
At Zoombak, we extended the positioning technology of our device to be able to use the signal strength and radiation patterns from the various cell towers to derive a lower accuracy location when GPS is not available (you need 4 visible satellites). And, WiFi can be used for even positioning by knowing the location of WiFi routers and map the RF signal.
Hi All
It's great to see this much interest in NAVigation via Signals of OPportunity. I can't reply to everyone individually and certainly can't get into huge discussions, I've scanned this thread and thought I could give you some information to help clear some of the mist.
1 - Radio positioning is certainly not new, people are discussing Rosum here, and (in a round about way) Cambridge Positioning Systems - the latter funded my PhD at Cambridge in this topic, and I've been driving developments in this field for the last 5 years. I'm not claiming to have invented multilateration or opportunistic positioning, what we have been doing at BAE is working on removing a lot of the restrictions discussed on here - for example getting rid of the need for access to a database someone else created of all the transmitter locations, or access to differential corrections from a reference receiver. A lot of the "this is not new" comments refer to differential positioning using reference receivers and having access to databases of transmitter locations (Rosum, the old Cursor positioning system from Cambridge Positioning Systems, etc). We consider those aspects to be undesirable constraints on a flexible opportunistic positioning system and don't rely on them. The system determines the transmitter locations itself, or gets by witout actually needing to locate the transmitters at all (for example our indoor positioning system does not aim to or need to locate the transmitters to function) We have developed some Simultaneous Localisation and Mapping algorithms (again not pretending to have invented the concept, just developing new algorithms building on these methods for use in opportunistic radio positioning) to aid the learning process and allow operations during GPS denial but before any transmitters have been fully calibrated via GPS, and we also exploit the fact that we are not limiting ourselves to jerry-rigging existing devices (e.g. cellphones) to do things they weren't designed for. We also look at some exotic concepts that are too computationally expensive or demanding in hardware to ever be applicable to the civilian sector, but are applicable to other sectors.
2 - We record as many metrics as we can - phase, phase rate, arrival of certain repetitve signal structure (time of arrival), signal strength, etc. We use different metrics in different environments - for example signal strength is more useful indoors to discriminate motion than outdoors. See my ION paper for more on the indoor system http://www.plansconference.org/abstract.cfm?meetingID=36&pid=51&t=C&s=1
3 - The entire concept is based around learning - the system gets better with use. When GPS is available you can start learning about the locations of the transmitters around you, their signal stabilities, start recording signal strength fingerprints, etc. Most (but not all) types of radio transmitter can be localised by our techniques. So imagine driving into a city along a motorway - you start to learn about the DAB transmitters, DVB, cellular etc available and start to localise them. Even without fully determining their location you quickly determine what driving East looks like in "radio eyes" versus driving North based on relative arrivals of repetitive timing structures within digital broadcasts, etc. So already you can handle short dropouts and freewheel through short GPS dropouts (a few minutes) using the opportunistic radio data with only a few minutes of operation. The further to go and more you have the system on, the better, and eventually you work out where all the transmitters are (short range cellular are located very quickly, long range DAB, DVB etc take more time to locate). Eventually you have enough data to confidently state where the transmitter is and it goes in the database. These signals punch into cities much better than GPS, so calibrating these sources on the way in means that you can use them during GPS dropout inside the city. The accuracy depends on a whole host of factors - typically ~10-150 metres, and