Filed under: iPod Family, iPhone
Looking Forward to the 3G iPhone: GPS
There are just two weeks left until the 3G iPhone bows with its new onboard GPS. The new iPhone will use several location methods using data from providers including Skyhook Wireless, Google Maps and the US Department of Defense NAVSTAR Global Positioning System. From most to least accurate, these are discussed after the jump.GPS. The US Department of Defense has built and deployed a number of Medium Earth Orbit satellites. These units emit microwave signals that your iPhone will be able to detect and use to triangulate your position to extremely close proximity.
GPS capabilities are nothing new to smart phones but the iPhone provides a great match between the technology and simple third party application development with Apple's well publicized Core Location library. Look for third party apps to support all kind of tagging and tracking features.
When outside, with a clear signal (no trees or tall buildings) GPS can locate you to within a few feet of your true location.
WiFi Positioning. SkyHook Wireless offers extremely accurate WiFi positioning. The iPhone or iPod touch scans local WiFi and WiMax routers in your area and uses their MAC addresses to search SkyHook's databases to position you from that data.
This works great when WiFi routers stay still. This works terribly when people pack up their WiFi routers and move with them to, say, Kentucky. That having been said, SkyHook data does get updated.
It provides pretty accurate positioning and can usually locate you within a few hundred feet of your actual location, even though people and their routers will continue to move to Kentucky and other places. WiFi positioning can locate you to within a city block of your true position.
Cell Tower positioning Less accurate than WiFi location, Cell Tower triangulation figures out where you are by mapping Cell Tower locations. Cell Towers, which never pack up and move to Kentucky, provide stable guidepoints located every few miles.
Although the iPhone prefers to use WiFi and GPS when available, Cell Towers provide a pretty good fallback -- usually locating you to within a half mile or so of your true location.
IP Location. To be fair, let me just say that I have never once seen the iPhone actually use this method. Then again, I live in a major metropolitan area; I haven't given it a very good try. This last ditch approach uses IP location to find the nearest mapped Internet Provider's central office.
This is a solution of last resort. The returned data is typically up to several miles off your actual location-unless you happen to be visiting your IP that day.
As you can see, the iPhone uses a rich set of geopositioning tools. Skyhook tells me that the FindMe application I wrote for a TUAW reader a few months ago, which will now be replaced by the SDK's built-in Core Location, has already been used several million times. Between new location aware technology like social networking and tried-and-true favorites like Geocaching, the iPhone is poised at the forefront of a geopositioning revolution.
Reader Comments (Page 1 of 2)
Richard said 2:47PM on 6-26-2008
^WAHHHHHHHHHHBULANCE.
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Adam said 4:59PM on 6-26-2008
Can someone please ban this a-hole. All he does is rip on Erica's posts and doesn't even contribute anything.
totoro said 3:05PM on 6-26-2008
Erica, what about A-GPS?
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Jon said 3:55PM on 6-26-2008
http://en.wikipedia.org/wiki/AGPS
totoro said 4:03PM on 6-26-2008
hah, thanks. I was referring more to the article though-in an article about the iPhone 3G's GPS abilities, shouldn't it mention A-GPS, without having to Google? ;p
junk_mail77 said 3:12PM on 6-26-2008
A-GPS = Assisted GPS. It is just regular GPS in combination with cell tower positioning. I don't think WiFi and IP location are technically considered part of A-GPS. Just do a web search for more info.
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SpinThis! said 3:40PM on 6-26-2008
http://en.wikipedia.org/wiki/A-GPS
Tony said 6:29PM on 6-26-2008
It's not cell tower positioning - that's a common misconception
AGPS loads the alamanac and ephemeris data from a remote server rather than load it from the satellite (which only sends at a few bytes per second) - it can reduce the fix time from several minutes to a few seconds in an ideal case.
It can also offload the calculations made by the chipset onto the more powerful AGPS server. although I don't thing the iphone will do this as it's got a reasonably powerful processor on its own.
The wikipedia link is quite instructive on the details.
fileai said 3:26PM on 6-26-2008
I already love using Google Maps on my iPhone to plot out directions, view the traffic situation, and to be able to find an alternate route if needed.
Once it is able to know exactly where you are in real-time, it will completely be able to replace any hand-held GPS devices. As my car nav DVDs go out-of-date as time goes on and new roads are built, this will be invaluable.
C'mon, July 11! :)
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tevetorbes said 4:48PM on 6-26-2008
I could be wrong, but your new iPhone will NOT be able to totally replace your handheld GPS device as it will NOT support turn-by-turn directions right out of the box.
Whether or not this functionality will be available via a 3rd-party application remains to be seen, but the Apple SDK says the following:
"Applications may not be designed or marketed for real time route guidance; automatic or autonomous control of vehicles, aircraft, or other mechanical devices; dispatch or fleet management; or emergency or life-saving purposes."
Which means that turn-by-turn navigation is unlikely.
Now, I'm a fanboy myself, but let's get real: the iPhone GPS functionality seems a little janky out of the box, and I'm rather disappointed. Why more people aren't also expressing this disappointment is curious to me: do people not CARE to have turn-by-turn directions (doubtful) or do they just not UNDERSTAND that this is the case (more likely).
Basically you're getting the functionality that the iPhone CURRENTLY HAS (ie the ability to locate yourself) with *much* better resolution. But don't think that you'll be strolling down the sidewalk and your iPhone will say "in 300 yards, turn right" so that you can make it to Starbucks.
Nay said 3:26PM on 6-26-2008
I though AGPS used cell towers to retrieve gps info since the cell towers have better line of sight with satellites and then that info is relayed to your phone.
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Tony said 6:31PM on 6-26-2008
You can use AGPS without any cell towers at all.. it's not only used in mobile phones.
jescoolman said 3:41PM on 6-26-2008
My mac geek father said something about how the new iPhone's GPS will be a subscription based service. Will using the GPS on my new phone cost me anything extra? I'm in the US. Is there a website out there that confirms this info?
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Matthew Yohe said 9:11PM on 6-26-2008
You should probably tell him he's wrong.
Nick said 3:56PM on 6-26-2008
I guess we all missed the mass migration of routers as they left for the greener pastures and clear skies of the Bluegrass state... that would have been a sight.
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mentalsticks said 4:15PM on 6-26-2008
And... another filler.
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rvinny said 4:41PM on 6-26-2008
"Cell Tower" Positioning is better than WiFi (Skyhook, Navizon). Look up TDOA. It is the predecessor to A-GPS and what AT&T is currently using to be FCC compliant. Accuracy ranges from 3m-30,000m depending on site density, terrain, etc. etc. GPS's are installed at cellsites but get they your location via timing. GPS is only reference.
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Tony said 6:34PM on 6-26-2008
Depends on where you are.
At one point the Skyhook database had my wifi router in it. It pinpointed my house exactly :p
OTOH Cell tower positioning can be hillariously innacurate - for example all the local cell towers are broadcasting the coordinates of the city centre, so all google maps give me is a picture of the city with a circle round it... not very useful. Most of the provincial towers don't broadcast any data at all.
The real fun ones is the ones that are simply wrong - in the right places Google maps thinks I'm located somewhere in the atlantic ocean :p
From what I hear in the US they seem to make an effort to have the towers broadcast reasonable coordinates.. that's not so elswhere in the world.
junk_mail77 said 7:02PM on 6-26-2008
What's strange in all the iPhone 3G GPS discussions I'm seeing is that no one is mentioning AT&T's Navigator service (http://www.wireless.att.com/source/uconnect/navigator/). I have to guess that AT&T had something to do with the SDK restriction on turn-by-turn apps, and I also have to guess that they're not going to let TomTom release a turn-by-turn app for the iPhone either. Especially with the subsidizing of the 3G, AT&T is going to definitely want to protect its opportunities for increased revenue through services like Navigator.
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Mike said 9:17PM on 6-26-2008
I wonder if someone will write an add-on to use terrestrial-based gps correction data to get even more accurate results....
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