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Forget GPS, Hello WPS

timothy posted more than 9 years ago | from the ded-reckoning dept.

Wireless Networking 286

No France writes "A company known as skyhook wireless has announced the commercial availability of its Wi-Fi Positioning System, or WPS. The company has compiled a database of every wireless access point it can find in a given city. When a mobile user running th Skyhook client is in a recorded area, their position is calculated by selecting the surrounding signals and comparing them to the reference database. Currently there are 25 US cities mapped, including New York City, Boston, Chicago, Los Angeles and San Francisco. Apparently this device is accurate to within 20-40 meters, though one has to wonder how well it deals with people moving their wireless access points."

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The Positioning Sledgehammer (2, Interesting)

Theo de Raabt (893376) | more than 9 years ago | (#12878439)

All this effort to develop technology to determine your location is great if the reason for finding your location is because you're lost. But, otherwise, it seems like another case of the technology industry developing a new market for devices of questionable usage. Throw legitimate privacy issues into the mix - generally in the US at least and certainly elsewhere - the thought of some anonymous entity determining my location is positively horrifying. I can't help but think that this is one of those situations wherein the instrument precedes any of the truly challenging work of determining sensible, useful applications. (If one more dull-headed marketing guru uses the example of Starbucks ringing a phone as I walk by..) Why is it so difficult to simply self-identify my location rather than relying on the sketchy availability of GPS satellites or databases of WiFi APs and doing all that trigonometry. Here I am standing at 44th and Broadway, based on my profile and previous activities, give me some insights into other activities in the area? Or, are any of my friends within 6 blocks of me? PDPal was a project that provided a map and allowed you to target your location - easy-peasy. Dodgeball goes a light year beyond this, using technology that nearly everyone has in their pocket - a cell phone. No GPS, no WiFi positioning hacks, just a cell phone SMS. Is it because discovering application proves so difficult that the cart, burdened with gizmos, leads the applications cart?

Re:The Positioning Sledgehammer (3, Funny)

Technician (215283) | more than 9 years ago | (#12878703)

Or, are any of my friends within 6 blocks of me?

They only way a free AP sponsor would be interested if any of your friends are within 6 blocks would be to suggest you all meet at Starbucks.

Re:The Positioning Sledgehammer (-1, Flamebait)

Anonymous Coward | more than 9 years ago | (#12878709)

Oh, my God! What is with the fscking mods lately?! They all seem to be infected with some kind of negative mod infection! Hey, flamebait mod, get a damned enema!

This sounds really handy (-1, Redundant)

Anonymous Coward | more than 9 years ago | (#12878441)

Well, then again maybe not.

Too Simple (5, Funny)

nxtr (813179) | more than 9 years ago | (#12878442)

They might as well give everybody a peice of paper with a huge X on it that says 'You are here'.

Mine's a bit derivative, but... (0)

Anonymous Coward | more than 9 years ago | (#12878680)

"I'm with stupid ^"

...what? (0, Troll)

CommanderNacho (887836) | more than 9 years ago | (#12878443)

...and you can geocache with this how?

Re:...what? (1)

croddy (659025) | more than 9 years ago | (#12878649)

more to the point, how can we turn this into a blog???

fp (-1, Offtopic)

Anonymous Coward | more than 9 years ago | (#12878450)

first posttttereeeeski! yesireeeeski

20 - 40 meters? (3, Insightful)

Anonymous Coward | more than 9 years ago | (#12878452)

20 - 40 meters? Who will be forgetting GPS with that kind of crappy accuracy?

Re:20 - 40 meters? (3, Funny)

ouzel (655571) | more than 9 years ago | (#12878719)

Why, when you young whippersnappers were still in diapers we were feeling lucky to get 100m accuracy with SA enabled.

AND we had to walk uphill both ways in the snow to get it.

Oh man. (0, Redundant)

man_ls (248470) | more than 9 years ago | (#12878453)

I work for this company, collecting positioning data. Let me tell you, it's a slick setup, and they have a very novel idea for positioning.

Assuming people don't get swap-happy and trade access points all over the place, the reliability should be very high, too.

Re:Oh man. (0)

Anonymous Coward | more than 9 years ago | (#12878548)

Hi great blog, it really taught me everything I needed to know about life. Thanks

Now, I work for a company that supplies many of the world's top armies with landmines. Our clients absolutely insist on the highest quality mines for blowing to pieces little dark skinned kids who live in poor places. Our reliability is excellent.

Re:Oh man. (4, Insightful)

nmb3000 (741169) | more than 9 years ago | (#12878636)

To be honest, I don't care how novel their ideas are. Using a system where position is located based on such arbitrary measurements is not only silly, but a waste of time. Not only can anyone move the access points around, but as they get shut off or more get added it will only make things worse. Also considering it can be influenced by minute things like weather and the position of the microwave in the apartment across the street make it a waste of time. You'd need to rescan it at least monthly to maintain even 20-40 feet (screw that) accuracy.

Let's see, a near-absolute positioning system based on immobile and unchanging (or extremely slowly) data, or something based on what could probably be described as a chaotic system? Not to be a jerk about it, but "Forget GPS"? More like "Ignore WPS".

Re:Oh man. (1)

c1pher (586281) | more than 9 years ago | (#12878773)

"To be honest, I don't care how novel their ideas are. Using a system where position is located based on such arbitrary measurements is not only silly, but a waste of time."

Indeed. Sounds more like these two [skyhookwireless.com] conned some venture capital money out of some schmucks, using a lot of technological gibbirish to make it sound like a untapped gold mine venture.

How reminescent of the 90's. :-)

Re:Oh man. (0)

Anonymous Coward | more than 9 years ago | (#12878775)

even 20-40 feet (screw that) accuracy.

Its 20-30 Meters you FUCKNUT!

Re:Oh man. (4, Insightful)

andy jenkins (874421) | more than 9 years ago | (#12878787)

Yes, but my iPaq has Wi-Fi not GPS. And the screen can show a good map.

I could ensure I'm always carrying a GPS reciever or just a city map but you know what, I own both these and only carry them when I know I need them. Which in the case of GPS, is never.

Re:Oh man. (1)

nacturation (646836) | more than 9 years ago | (#12878796)

As a commercial venture, I'd have to agree with you. However, if this were some guy's hack I'd be impressed and would applaud the effort that went into it. Unless it is based upon SSIDs (yeah, right... found 18 "Linksys" at this location...) or MAC address (much better) the accuracy is sure going to suffer.

Re:Oh man. (2, Insightful)

Johnny Mnemonic (176043) | more than 9 years ago | (#12878651)


Assuming people don't get swap-happy and trade access points all over the place, the reliability should be very high, too.

Well, that would be an issue, wouldn't it? And, unlike, say, a system you own, other folks own and control these datapoints that your system depends on.

I have to say that I regularly reconfigure my WAP becasuse, well, it's mine, and I chose to use it like a toy. I notice that a great many of my neighbors have WAPs of their own, but, not so surprisingly, I find that everytime I look the configuration is a little different--cause they're playing with theirs too.

You know, they lose power so vanish for awhile. Or are configured for security, but then the owner decides that's too much a pain in the neck so reverts. Or buys a different brand, hoping to get better signal. Or people move away--I hear that "rentals" are common in "urban centers", which tend to attract a transient demographic. Or the mix changes for any number of other reasons.

I hope for your sake that you guys took a snapshot and then took another 3 mos. later to determine average drift; I suspect that it'd be significant, enough that you couldn't triangulate off of it, at least.

Really, at this stage of your product cycle you shouldn't be guessing if this is feasible; you should be able to respond to this (obvious) criticism in the strong affirmative, without the guessing you displayed. How else can I be expected to trust it? And while it may be accurate for a month or so, it'll only be updated once a year? Gee, I sure hope I'm trying to get my position at the beginning of the year rather than at the end.

Sorry to be harsh, but really this is one of the stupider ideas I've seen posted here. You may as well give directions based on the make, model, and color of cars parked in driveways. Those don't change, much either. But over the course of a year, I guess they actually do, huh?

Been there, done that! (4, Informative)

wintahmoot (17043) | more than 9 years ago | (#12878460)

PlaceLab [placelab.org] has been doing this for a while, and it's free.

Re:Been there, done that! (4, Interesting)

Myself (57572) | more than 9 years ago | (#12878629)

Strange how the world turns, I just mentioned PlaceLab to a friend before loading Slashdot. Spooky!

PlaceLab's big advantage is the ability to use multiple sources. Wardriving data is just one potential input. If you have a GPS receiver and a wi-fi card and a CDMA phone all connected, it'll use whichever is giving the most trustworthy results. So you can move smoothly between urban, rural, and indoor environments.

What absolutely makes me giggle is this: "Morgan adds that GPS typically only locates things within a few hundred meters, whereas the Wi-Fi location system can get within 20 to 40 meters of an object."

Re:Been there, done that! (1, Interesting)

Anonymous Coward | more than 9 years ago | (#12878658)

Actually, having been part of the PlaceLab research team, I can confirm that "WPS" can be far more accurate than GPS. Consider that GPS is a single sample, and PlaceLab is a particle filter system which leverages many thousands of correlated samples with extra inputs such as relative signal strength.

Re:Been there, done that! (2, Informative)

Myself (57572) | more than 9 years ago | (#12878788)

But the original wardriving that put the APs into the PlaceLab database was using GPS as a reference.

I see what you're saying though, that a moving GPS on a single wardrive will have some error based on atmospheric effects, but repeated resurveys of an area on different days would tend to average these out, similar to the long-term averaging of a stationary GPS receiver.

My point was that the spokesdude in the article is either misquoted or misinformed about the accuracy of GPS, and that the neither Skyhook nor PlaceLab is likely to return better outdoor results than a consumer GPS receiver. Indoors is where this concept really shines.

Re:Been there, done that! (2, Interesting)

kormoc (122955) | more than 9 years ago | (#12878751)

that's funny, mine typically is about 3 meters.

see http://www.delorme.com/earthmatelt20/waas.asp [delorme.com]

"it is possible where WAAS is available to experience accuracy of under three meters for the majority of tracking time."

Mine has never been more then 10 meters off.

Re:Been there, done that! (5, Informative)

suineg (647189) | more than 9 years ago | (#12878752)

Well think about the fact that you pretty much need to be within 20 to 40 meters of an AP to even pick the signal up then it would make absolute sense.

What a joke... (5, Funny)

nemostultae (524156) | more than 9 years ago | (#12878466)

Apparently this device is accurate to within 20-40 meters

Hell, I can guess where I am to that accuracy. I thought GPSs where accurate within 5-8 meters nowadays. And this sounds really useful out in the open ocean, you know, where all those rouge wireless access points hang out.

Re:What a joke... (0)

Anonymous Coward | more than 9 years ago | (#12878514)

Trimble sells sub-meter and sub-centimeter GPS systems. This wireless setup may be useful in a guess-which-block-I'm-on kind of way.

Re:What a joke... (1)

Svet-Am (413146) | more than 9 years ago | (#12878534)

Really? I know that sub-6-meter GPS resolution was long protected by the US military for security reasons. When was that range opened up for public consumption?

GPS SA off since may 1, 2000 (3, Informative)

slew (2918) | more than 9 years ago | (#12878582)

GPS selective availability has been turned off since May 1st 2000..Here's some more information [kwarc.org] .

Basically, the military figured out how to easily jam GPS in an area. But before then, there were GPS field units available that averaged out the error and got better than 2-3 meters so that it didn't really matter that much...

Re:What a joke... (4, Informative)

Andy Dodd (701) | more than 9 years ago | (#12878741)

Sub-5-meter accuracy: As another poster pointed out, SA was turned off a while ago. Pretty much any GPS unit will be accurate to within 5 meters if it has a decent signal. With tricks like code smoothing, most errors are probably less than 3-4 meters even for a moving receiver.

Sub-meter accuracy: A little bit of position averaging + basic DGPS makes this easy for a stationary receiver, even when SA was on DGPS could cure the intentionally added errors. Very difficult to use with a moving receiver unless combined with an inertial navigation system. (Rare except in modern airplane navigational systems)

Millimeter accuracy: Also possible before SA was turned off, but required the receiver to be stationary for a long period of time, and required significant postprocessing of the data using a variant of DGPS. It still requires stationary receivers for nonmilitary systems.

About the only thing that can't be done without a method for decrypting the P code is sub-centimeter positioning of a moving object. Even with the P code available it can't be done without combining a high-grade inertial navigation system with the GPS system.

Re:What a joke... (2, Funny)

gardyloo (512791) | more than 9 years ago | (#12878711)

And this sounds really useful out in the open ocean, you know, where all those rouge wireless access points hang out.

Ah, yes, the pink ones.

Not very accurate (1)

westyvw (653833) | more than 9 years ago | (#12878469)

20 to 40 meters of accuracy? I work with various grades of GPS and even with low accuracy gps I can get within 10 feet no problem. I mapped wireless access points before and they really turn out to be VERY inaccurate overall.

Oh well maybe some fun could be had, like PHYSICAL address spoofing.

Re:Not very accurate (1)

Mozk (844858) | more than 9 years ago | (#12878654)

WPS actually stands for What a Piece of Shit, which would explain the inaccuracy.

but there's really no point! (1, Insightful)

cryptoz (878581) | more than 9 years ago | (#12878470)

If you're in a major city, you seriously don't need GPS or any positioning system. Look out the window of your car, ask someone, etc. GPS is needed and useful when you're NOT in the city, when you're out in the middle of nowhere or on a highway getting lost. Cities are the one place a positioning system is useless, so why develop it there?

Re:but there's really no point! (1)

Mr2001 (90979) | more than 9 years ago | (#12878488)

A human being may not need GPS to figure out where he is in a city(*), but it's definitely useful for automated navigation systems. It's nice to be able to press a button and have a friendly voice guide you back to the freeway.

(* though that's debatable - what if you're in an unfamiliar area, and it's the middle of the night so you can't find anyone to ask?)

Re:but there's really no point! (1)

nmb3000 (741169) | more than 9 years ago | (#12878652)

It's nice to be able to press a button and have a friendly voice guide you back to the freeway.

Until somebody unplugs their AP and the friendly voice tells you the freeway has gone missing.

Really though, it's not like a GPS receiver is going to cost any more than an "WPS" receiver. Even dirt cheap GPS receivers are accurate withing about 10-15 feet, all day, every day.

Re:but there's really no point! (4, Interesting)

JanneM (7445) | more than 9 years ago | (#12878504)

Cities are the one place a positioning system is useless, so why develop it there?

You haven't tried to find a specific place in Tokyo or Osaka, have you?

Having a Gps is a life saver. You look up the place you want to go to on an online map, get the coordinates, and you're set. Without it, it's just too easy to miss the right building, mistake streets for each other or get lost in many other creative ways.

You could argue the other way round (and just as stupidly) - since there's one single highway or road in the entire area, why would you need a Gps to know which one you're on?

Re:but there's really no point! (1)

TheSloth2001ca (893282) | more than 9 years ago | (#12878516)

what if there are no roads??? and in a city if all else fails just stop teh car at an intersection then look it up on a road map. u do have a road map in teh car dont u?

You've never been to Japan I see! (2, Informative)

KNicolson (147698) | more than 9 years ago | (#12878566)

Road naming is non-existant outside major thouroughfares; it works more by an irregular grid numbering system of blocks, not the roads in between them. House numbering is similarly vague, with no guarantee that house number 2 will be beside number 3 or 4. Block nameplates are usually pretty small and not in easy-to-predict places very often; GPS, even for pedestrians, is very useful in Japan. Even the taxi drivers haven't a clue where most places are!

Re:but there's really no point! (2, Funny)

JanneM (7445) | more than 9 years ago | (#12878626)

u do have a road map in teh car dont u?

I'll get a road map in my car the moment I get a car. I'll put it right next to my dictionary.

Re:but there's really no point! (0, Troll)

cryptoz (878581) | more than 9 years ago | (#12878517)

Eh? I think you have the wrong country here. It's talking about cities in the United States, not Japan...your examples are completely irrelevant!

And with an accuracy of 40 meters, how does it even know what street you're actually on? There are plenty of places where there are streets inside of 40m from each other.

Re:but there's really no point! (1)

JanneM (7445) | more than 9 years ago | (#12878589)

Eh? I think you have the wrong country here. It's talking about cities in the United States, not Japan...your examples are completely irrelevant!

I talked about Japanese cities since that's where I have my most recent experience of this. Rest assured that I can get lost in any city in the world, no sweat.

Yes, you can ask people, bring a map, even a compass and so on. But you can do that (and should, if you aren't following roads, Gps or not) out in the countryside as well. I didn't say things were impossible in a city without navigation aids, I just stated that they are far from useless - on the contrary, they are pretty handy devices in a dense urban area.

And with an accuracy of 40 meters, how does it even know what street you're actually on? There are plenty of places where there are streets inside of 40m from each other.

It doesn't. I fully agree that this particular system stinks, basically. Even I know where in Osaka I'm at with 40 meters accuracy (well, usually). It's singularily unhelpful to know that I'm probably within three or four block of where I'm going, maybe, if nobody has moved or messed with their wifi equipment in the area.

Your statement was about navigation systems in general, however. And good systems, like the combined Gps/celltower system in my mobile phone, is worth its weight in gold in urban areas.

Re:but there's really no point! (0)

Anonymous Coward | more than 9 years ago | (#12878611)

pedantic post:
Grandparent poster did not specify the country. The parameters specified were major and city. Since Tokyo and Osaka ARE indeed MAJOR CITIES in Japan, the parent poster was indeed relevant.
Furthermore, the parent poster DID specify roads in Japan, which I've been told are confusing even to Japanese people who are unfamillar with the area, not to mention a foreigner who may or may not have the communication skills necessary to navigate said roads by asking for directions.
Also, the grandparent said GPS or "any positioning system", which the parent chose GPS from, which has far greater accuracy than 40 meters.
Therefor, I wish I had 2 mod points left, one "+1 insightful" for JanneM, and one "-1 unnerdly" for cryptoz, for failing to think clearly before posting to /. ;)

Re:but there's really no point! (0)

Anonymous Coward | more than 9 years ago | (#12878619)

Calm down there Cryptoz-boy. It's being rather anal-retentive to be all indigent about the country used in the example as if that makes any difference to the tech.
Parent clearly stated that GPS was "a life saver", get it? GPS. Your "40 meters" comments are totally unrelated to Parent.

Re:but there's really no point! (0)

Anonymous Coward | more than 9 years ago | (#12878506)

For automated systems, not for people. This might also be useful for inside buildings.

Re:but there's really no point! (2, Funny)

cryptoz (878581) | more than 9 years ago | (#12878527)

Say what?!

Determine your location in a building with an accuracy of somewhere inside 40 meters. Oh yeah, that's useful. Which floor again? Which room? Eh?

Re:but there's really no point! (0)

Anonymous Coward | more than 9 years ago | (#12878676)

If you live in a big city you do need GPS, because you can and frequently do get lost. I can understand someone like yourself living in a small town of a few thousand people wouldn't need GPS navigation, but where I live in Tokyo it is neccessary to navigate the city!

Re:but there's really no point! (1)

Technician (215283) | more than 9 years ago | (#12878736)

GPS is needed and useful when you're NOT in the city, when you're out in the middle of nowhere or on a highway getting lost. Cities are the one place a positioning system is useless, so why develop it there?


Want to bet? I use mine most in the city. On my commute of about 30 miles, I hit the backup due to the sideways semi. I take the next exit whatever it it. I let the in car nav (GPS based) route me through the housing complex to get back on past the blockage.

Ever notice how many housing developments are designed to not make it easy for someone to enter from one end and find the way out on the other. In car nav fixes that problem and makes it easy to get from one major street to another or pass a blockage and emerge past the stoppage.

A good GPS nav system saves time and gas in the city. In time and gas saved, mine has paid for itself in just city driving.

Re:but there's really no point! (1)

wramsdel (463149) | more than 9 years ago | (#12878782)

On the contrary, a city is exactly where you need GPS if location-aware advertising is your gig. Trust me, advertisers won't be happy until they can display a popup on your phone for Starbucks' new chocolate-hazelnut-vanilla-mochalattechino as you're walking by the Starbucks. I think the "location based services" to which Skyhook refers on their main page are none other than these advertisers. That and the laptop-LoJack folks under the first news entry.

Dynamic data would be better (2, Insightful)

photon317 (208409) | more than 9 years ago | (#12878480)


Rather than trying to maintain a static database of AP locations and signal strengths, they should just put some live wifi nodes out there with real GPS on them and track the AP map in realtime as it shifts. Or they could give free service to a select small percentage of customers in return for attaching a GPS device and helping recalibrate the map with some background software once a month or something.

wigle.net (1)

X00M (526040) | more than 9 years ago | (#12878481)

looks like this is already being discussed over at wigle.net

Or, use JASYKPS (0)

Anonymous Coward | more than 9 years ago | (#12878491)

Only accurate within 30-40 metres... pffft! Why not use JASYKPS (Just Ask Someone You Kultz Positioning System) - it's free and very accurate. (Note this system fails dismally when no-one else is around)

The problem: lousy baseline? (0)

Anonymous Coward | more than 9 years ago | (#12878521)

It's no wonder the technology is only accurate to 20 to 40 metres. GPS uses multiple satellites that are hundreds or thousands of kilometres apart, plus very high timing accuracy (provided by atomic clocks on the satellites), to produce accurate measurements of position. Whereas WiFi can only get baselines of tens of kilometres at best, and I don't know what kind of timing accuracy they can get, but it's surely no better than what the GPS satellites can provide.

Bwhahaha (1)

gustgr (695173) | more than 9 years ago | (#12878524)

Forget GPS

Weeeeeee! This mean we can nuke the GPS stationary satellites now? ''Shut 'em down guys!''

FWIW, there ARE stationary GPS satellites (kinda) (1)

slew (2918) | more than 9 years ago | (#12878628)

It's probably not well known, but there have been effectively "GPS stationary satellites" in operation in major cities for quite a long time called WAAS. Basically WAAS (or Wide Area Augmentation System) has about 25 stationary ground system that correct for GPS signals with a signal that's compatible with GPS broadcasts. Originally designed by the FAA, it's really helpful for GPS car navigation systems...

Read more at this site [garmin.com] ...

Sometimes reality is better than you know... ;^)

Nope: Re:FWIW, there ARE stationary GPS satellites (1)

MDMurphy (208495) | more than 9 years ago | (#12878753)

WAAS is not "stationary satellites". There is such a thing, called a pseudolite, but that's not WAAS.

The ground stations generate the corrections, but these are sent to stationary satellites in geosynchronous orbit. A WAAS capable GPS receiver can receive those signals in addition to the GPS signals with a compatible GPS receiver. This information is in the linked article.

It's actually pretty useless for car navigation systems, but good for marketing. Since SA was turned down, the WAAS signals only are correcting for atmospheric or small timing errors in the GPS signals. These errors are fairly small. In a car doing down a highway the error is very tiny when compared to the "error" you get when a vehicle has moved 25 meters in the time between position updates. Additionally, WAAS corrected positions do not correct for errors that are local to the moving receiver, that is relections or multipath errors seen by the receiver but not by the reference stations. Those errors can easily be an order of magnitude larger than the errors WAAS might have corrected.

So for walking around a field looking for a rubbermaid containter filled with chotchkes, it might be handy, but for car navigation it's just so marketing can list it as another feature.

Position of each AP? (0)

Anonymous Coward | more than 9 years ago | (#12878540)

Who said that they, in fact, knew the exact position of every access point to begin with? Who cares if the known APs get moved, they most have accounted for that anyway.

Karma whore (0, Flamebait)

NanoGator (522640) | more than 9 years ago | (#12878552)

Cue karma-whoring privacy concerns in 3...2...

Re:Karma whore (4, Funny)

nametaken (610866) | more than 9 years ago | (#12878677)


I'm worried less about privacy, and more about how I'm going to tape my wireless access point to my roomba just to mess with them.

But then, with such poor accuracy, it's not like anyone will be worried about 40 or 50 feet here and there.

Only 20 to 40 meters? (2, Insightful)

meatflower (830472) | more than 9 years ago | (#12878558)

I honestly would expect it to be even worse.
If this determines position by signal strength wouldn't it then be dependent on the type of antenna you were using with your WiFi card? Sometimes my signal moves around even in the same position or drops significantly lower in "dead spots". What if I'm using one of those crazy Pringles can antennas?

"Hey! 100% signal here, I'm here, over there and...yep, that a ways too!"

Anyhow, what an awesome idea, I mean, it's not like we have anything like this in existence, you know, that millions and millions of dollars were put in to launch satellites into orbit. No, nothing like that, nothing that has 10 feet or less accuracy. Guess we should all start usin this POS. No thanks.

Re:Only 20 to 40 meters? (1)

nametaken (610866) | more than 9 years ago | (#12878689)


I'm thinking, worse than my wireless cards strength, what about that of the AP's around me? Wouldn't this have to work by triangulation, assuming all AP's broadcast with the same strength?

Moving APs (1)

suso (153703) | more than 9 years ago | (#12878562)

though one has to wonder how well it deals with people moving their wireless access points.

And thats exactly what it will not catch on. No company in their right mind would make products that counted on devices that aren't guarenteed to not be moved. Although it might work if the WiFi APs received GPS data and then acted as base stations to enhance the resolution of your GPS device. What I'd really like to see if GPS that worked in buildings and underground.

Re:Moving APs (1)

JanneM (7445) | more than 9 years ago | (#12878604)

What I'd really like to see if GPS that worked in buildings and underground.

We have that, sort of, in Japan. Modern mobile phones can use infro from the cell towers to trianglulate where they are and show you a map, indoors or out. It also helps the Gps-enabled phones to calibrate themselves a lot faster. Really convenient, and surprisingly accurate. Of course, it'll only work well in urban areas, but then, that's where you're most likely to need it indoor or underground anyway.

Re:Moving APs (1)

HermanAB (661181) | more than 9 years ago | (#12878756)

Well, first of all, there is no shortage of companies that are not in their right mind...

Secondly, this may be very useful for uhm, uhh, well, I dunno...

Interesting. . . . (4, Insightful)

Bagheera (71311) | more than 9 years ago | (#12878575)

. . . but I suspect ultimately of little practical value. Having done quite a bit of RF scanning on the WiFi bands in one of their listed cities (San Francisco) I've seen first hand how signals behave in that dense urban environment.

GPS and WAAS operate on time signals and highly accurate positioning. Cell towers would be inherently more accurate since thier positions are accurately known and don't change (except under very unusual circumstances.

WiFi nodes come up and down constantly, and their position is rarely going to be accurately known by anyone but the person who installed it - and chances are they're not telling "you" exactly where the node is.

Given "walk around surveying" to map the nodes, it's not really a surprise they have accuracy that's no better than an early 2 channel GPS receiver.

And, as others have pointed out, if I'm in downtown San Francisco (or any other city) I don't need my GPS to tell me I'm at 5th and Townsend. For directions there's Mapquest, Google, Yahoo Maps, etc...

Interesting technology. But it sounds more like something a hobbiest would come up with than business.

Re:Interesting. . . . (1)

Andy Dodd (701) | more than 9 years ago | (#12878754)

In addition, cell tower broadcasts are done with timing requirements nearly as stringent as those used by the GPS system. (In fact, most cell towers have a GPS receiver in them for the sole purpose of providing a time reference.) As a result it's possible to get a semi-decent position fix from cell towers without even relying on signal strength. Combine this with a few GPS signals and you get Augmented GPS, aka E911.

WiFi APs don't even come close to such timing accuracy.

20-40 meters? (4, Interesting)

Jurisenpai (261790) | more than 9 years ago | (#12878586)

Don't these people realize how accurate GPS positioning has become?

MGIS-grade equipment [trimble.com] can now give positions with sub-foot ( 30cm) postprocessed accuracy. Survey-grade equipment can get within 5-10 cm.

As neat as WPS sounds, I don't think that anyone will be giving up GPS soon if WPS can't get any more accurate than 20-40 meters.

Re:20-40 meters? (1)

RedWizzard (192002) | more than 9 years ago | (#12878657)

As neat as WPS sounds, I don't think that anyone will be giving up GPS soon if WPS can't get any more accurate than 20-40 meters.
That was my first thought. 20-40 metres isn't even good enough for street navigation. What is it good for, telling you which wireless cafe you're sitting in?

Re:20-40 meters? (1)

rehannan (98364) | more than 9 years ago | (#12878665)

Actually survey-grade equipment can give real-time positions within about 1cm via RTK GPS.

Re:20-40 meters? (1)

Jurisenpai (261790) | more than 9 years ago | (#12878693)

Point taken, but RTK equipment is insanely expensive and out of the price range of most small surveying companies (that my company deals with, anyway).

Re:20-40 meters? (2, Interesting)

Bastian (66383) | more than 9 years ago | (#12878669)

Yeah, but most GPS equipment of that grade falls into the "If you have to ask how much it costs, you can't afford it" price range.

The system I work with can do sub-meter, sub centimeter with post-process. It retails for ~$40,000 plus a couple thou for a DGPS subscription and a few hundred to a couple thou for the DMI (odometer) equipment. And its precision falls off sharply (to as bad as 5 meters) in metropolitan areas where you get the GPS signal getting blocked by and bouncing off of tall buildings.

My guess would be that this system is sort of the opposite - a relatively cheap solution that works well when you don't need incredible accuracy , and it probably works best in dense urban areas where GPS tends to perform the worst.

That said, I'm not entirely sure how big their market is, because I imagine most people that need positioning equipment and work exclusively in areas with good wireless coverage are probably the type of customers who can afford expensive GPS equipment.

Re:20-40 meters? (2, Informative)

Jurisenpai (261790) | more than 9 years ago | (#12878721)

I'm not sure what kind of system you're working with (or how old), but the system I linked to above is *very* roughly $3500. The software would add another $1500. So for about $5000, you have submeter accuracy. Multipath is still a problem, yes, but there have been great advances in solving that, too.

GPS has come down in price incredibly in the last few years. You don't even need a subscription to a DGPS service anymore.

Open Source DGPS? (1)

DigitalRaptor (815681) | more than 9 years ago | (#12878708)

I wish there were an open source DGPS project out there.

The premise seems simple enough: Have one GPS at a fixed position, and the other receives corrections via radio.

But I haven't been able to find anything.

My house sits on a large lot (over an acre) and I've wanted to survey it fairly accurately (within a foot at least) to recreate it digitally and be able to plan shops, gardens, landscaping, etc.

Re:Open Source DGPS? (1)

Bastian (66383) | more than 9 years ago | (#12878737)

I imagine that there's no open-source DGPS software because equipment that can receive a DGPS signal already has the firmware for decoding it built in. Why bother?

If what you're talking about is free DGPS service, that does exist, but only in certain localities. UW-Madison has set up several beacons and differential transmitters around Madison, WI, and they are free for anyone to use. I believe that the Ohio Department of Transportation has done a similar thing for the entire state, but I'm not sure if they let the public use it or not.

Re:Open Source DGPS? (1)

DigitalRaptor (815681) | more than 9 years ago | (#12878765)

What I'm talking about is using 2 separate GPS units, each connected to a linux box.

The fixed unit is on a known, surveyed point.

The other unit is out and about taking measurements. The fixed unit sends the mobile unit real-time data corrections.

Commercial DGPS equipment works in much the same way, but is very, very expensive.

Perhaps it's not possible to do what I'm thinking using a couple of old linux boxes, a couple off the shelf GPS's, and a means of communication (wi-fi, bluetooth, UHF / VHF radio) to send corrections, but since it's the way commercial systems work, it seems like it could be done as an open source project supporting any NEMA compatible GPS receiver.

Re:20-40 meters? (3, Insightful)

invisigoth (131518) | more than 9 years ago | (#12878734)

This can solve some problems associated with standard GPS. Namely, that satellite-based GPS systems fail when structures block line-of-sight to the satellites in the sky. This can include things like tall buildings in urban areas, or underground parking garages, etc. Since WPS is purely terrestrial, it can overcome many of these problems. Of course, satellite-based GPS is still preferable if you don't have these issues.

Giant leap for mankind... (0)

Anonymous Coward | more than 9 years ago | (#12878597)

Sometimes a new technology comes along, and you just have to say WOW! THAT IS COMPLETELY UNNECESSARY!

Useless? (2, Funny)

knightPhlight (173012) | more than 9 years ago | (#12878600)

I'm currently surrounded by the SSIDs, "linksys" and "default". Can someone tell me where I am?

Re:Useless? (1, Informative)

Anonymous Coward | more than 9 years ago | (#12878726)

Access point MACs are (mostly) unique.

Re:Useless? (1)

Subrafta (848399) | more than 9 years ago | (#12878757)

I was there yesterday -- you're at the corner of Walk and Don't Walk.

Re:Useless? (1)

cbiffle (211614) | more than 9 years ago | (#12878771)

GET OUT OF MY HOUSE!

Cellular towers (1)

HoeDing (828412) | more than 9 years ago | (#12878617)

Doesn't it make more sense to use the signals off of Cell towers? They are much more powerful, and fixed point.

Re:Cellular towers (1)

prockcore (543967) | more than 9 years ago | (#12878748)

Doesn't it make more sense to use the signals off of Cell towers? They are much more powerful, and fixed point.

They already do that.. that's how E911 works. My audiovox cellphone has it.. calculating my position based off the cell towers.

E911 (1)

Andy Dodd (701) | more than 9 years ago | (#12878763)

That (In addition to the ability to receive GPS signals) is what E911 is.

The fact that cell towers are in fixed positions and broadcast with strict timing requirements is why E911 works even when signals from less than 3 GPS satellites are available - the towers themselves are essentially used as "pseudolites" in the position calculations.

What about in your house? (0, Offtopic)

gremlins (588904) | more than 9 years ago | (#12878639)

Could you do something like this in your house? I know this sounds a bit crazy but I am trying to figure something out so I figure out where my roomba is inside my house. That way I could send it to rooms that get more traffic. This would require more hacks for Roomba but I got a good idea how to do that what I need is a way to figure out where Roomba is in my house.

Re:What about in your house? (0)

Anonymous Coward | more than 9 years ago | (#12878742)

Could you do something like this in your house? I know this sounds a bit crazy but I am trying to figure something out so I figure out where my roomba is inside my house.

Sure! First you'll need 10 access points with GPS coords. After that it will tell you exactly where your Roomba is (give or take 20 to 40 meters). Uh, how big are your rooms?

Re:What about in your house? (1)

Wizarth (785742) | more than 9 years ago | (#12878806)

LOL

forget gps? forget you! (1)

east coast (590680) | more than 9 years ago | (#12878661)

20-40 meters? try to navigate on that.

Not to mention the tons of other problems such as access points moving and disappearing and the inharently weak signal makes wps less reliable under minor amounts of interference.

it's a neat trick for someone who has nothing better to do but with as advanced as gps is and the ability to track via cellphone I don't see this having any real market.

Finally I can find my keys! (1)

icecow (764255) | more than 9 years ago | (#12878668)

I can use this technology to find my keys because I use RFID keys to open my front door and start my car. RFID is more secure then most people think, because it can be used in combination with keying in a short security code. RFID can be used in combination with biometrics for an unpresidented level of security. For example, to open my front door my RFID keychain has to be within 10 feet of the door awhile I shit in a special box.

Re:Finally I can find my keys! (0)

Anonymous Coward | more than 9 years ago | (#12878743)

I like the cut of your jib young man. Good work, keep it up

Default Names & Ad-Hoc Networks? (1)

djblair (464047) | more than 9 years ago | (#12878695)

Most people don't even bother to name their networks. "Linksys" "default" "netgear" are what I typically see.

> one has to wonder how well it deals with people moving their wireless access points

This is especially true with ad-hoc networks.

Not useful for typical GPS uses, but... (3, Interesting)

SnprBoB86 (576143) | more than 9 years ago | (#12878730)

20-40 ft? This is totally useless for street navigation, surveying, etc.

What this is useful for is grander scale positioning without the need for a GPS device built into a portable device.

For example, timezones are far larger than 20-40ft. Laptops could be configured to automatically adjust the timezone setting to match the closest access points, no GPS device needed. A weather monitor utility could always automatically show the local weather. A star map could be configured to show the local sky. I'm sure many people can think of others.

WIFI Range (0)

Anonymous Coward | more than 9 years ago | (#12878740)

Let's see. According to this ling http://www.linksys.com/products/wirelessstandards. asp [linksys.com] WIFI range is 100-150 feet for an indoors AP. In other words... Given a map of San Francisco and a list of APs, I can get roughly 30-50 meter location accuracy as soon as I can spot an AP.

Practical? (1)

mstefanus (705346) | more than 9 years ago | (#12878750)

I failed to see the practicality of this.

First the resolution; 20 meters? The common GPS receivers have around 3 meters resolution. Which one do I prefer? Well GPS of course.

Number two on the list, range and availability. WiFi signals are everywhere in large cities, but once you move away a bit then it is gone. What is the point of having a positioning system that only work in the city center?

Then there is the convenience. It depends on a database of APs, but APs are not things that you can use as landmarks. The rate of changes is much too quick. With the GPS? It works globally without me worrying about anything. Which one would I choose?

GPS rocks (0)

Anonymous Coward | more than 9 years ago | (#12878774)

I remember using it hiking, and found it quite useful. I hope that this technology spreads to other devices!

Old news, with GSM this has been possible for ages (1, Interesting)

Anonymous Coward | more than 9 years ago | (#12878776)

Hi, I'm working with GPS tracking and have just finished one of the worlds largest online tracking of a sail reagatta using GPS/GPRS devices. (watski.watland.net). Earlier I have worked with various other systems for tracking, one of them using the distance from a GSM antenna as the measurement. Every base station(antenna) keeps a log of wich GSM phones are in the area and the strength of the signal, if you cross reference this with other base stations you get a pretty accurate measure of the position, but still there is a huge difference between this and GPS. It is pretty hard to get the accurancy lower than 50 meters (you probably wouldn't navigate your car after this...)

So, what I try to say, is after several years of working with various technologies, it is hard to match GPS on accuracy, then there is reliability and different service providers and so on...

WiMax? (1)

Piranhaa (672441) | more than 9 years ago | (#12878781)

I wonder how long after WiMax is released that the same type of method can be used. It could really be a better technology than GPS if done correctly. I really don't like waiting for my GPS handheld to determine where every satellite is and connect to each... Just my two dollars -P-

jungle (1)

ad1 (881260) | more than 9 years ago | (#12878786)

Are there any access point in the jungle? It will not be practicle for outdoor usage.

SSID or MACs? (1)

prostoalex (308614) | more than 9 years ago | (#12878800)

The article states:
The way it works is that the company has compiled a database of every wireless access point in a given a city. It did this by having people literally drive the streets "listening" for 802.11 signals. Using the unique identifier of the wireless router, it notes in the database where the access point is located.


Is that unique identifier such as SSID or access point MAC address (is that even accessible to a client)? Since a large number of people would check "Do not broadcast the SSID" following their manufacturer's manual on security, while the other would leave, as people before mentioned, some default setting.
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