iPhone 3G: 5 Days and Counting Down to GPS!

iPhone Black: 3G Form Factor Rumor Roundup: Countdown to WWDC

This is it. We're in the home stretch. Third period power play, clock's all but run out, and Steve Jobs is cranking back for the slap shot. In 5 days we find out if Apple scores the go-ahead goal, the two-peat for smartphone (even gadget) of the year, or if they bounce it off the goal post with their mostly evolutionary, not so much revolutionary, next generation handset.

Yesterday we mentioned one big change: the fast 3G data chip. The other big change? GPS. (Global Positioning System).

What is this and why should it matter to you? Read on after the break!

The original iPhone (now dubbed iPhone 2G) launched without any location aware services. While it might or might not have known where it was, it didn't share that information with you. When firmware 1.1.3 was released, however, that all changed.

Using Google's cell tower mapping (where Google is recording the GPS positions of cell phone towers -- AT&T, Verizon, Bell, etc. in North America and increasingly around the world), and Skyhook's WiFi router mapping (where Skyhook drove down your street and wrote down the position and unique ID of your wireless router), this let the Google Maps app in the iPhone 2G kinda-sorta get a fuzzy idea of where it was. Drawbacks? It was about as precise as a few city blocks, and if for example, you were in New York but the closest router had just been shipped there from LA, you'd just as likely show up as being in the router's last-recorded location, LA. In other words it ranged from good enough to potentially equal parts comical or disastrous. Also, since transmitting the map graphics required an EDGE connection, it wasn't exactly speedy.

With the iPhone 3G, location becomes as precise as a few feet. Using an array of some three dozen satellites constantly beaming their signals down to us, the iPhone 3G trilaterates (i.e. figures out) exactly where we are based on which satellite's signals it receives and the distance of each of those signals. (Typically four or more signals are required, as unlike triangulation, it needs to calculate the timing of the signals as well). Geeky much? There's more.

GPS isn't all roses. It can often take considerable time and can burn a lot of power. It's another radio to leave running, and depending on signal strength, it can take minutes -- sometimes a lot of them -- to acquire satellites. Then its got to spend more time and power to crunch all the numbers.

To help compensate for this, the iPhone 3G uses aGPS (assisted GPS). With aGPS, cell phone towers handle acquiring the satellite signals and pre-crunch down the location information. Since cell phone towers, unlike tiny handsets, can host very large radios and much more computational power, they can receive more and better signals and they can keep track of location much faster. This means, when your iPhone 3G GPS goes active, a lot of the heavy lifting has already been done by the nearby cell towers, and it can just fetch the data and do the final, specific to its own location, calculations. This consumes less power and requires much less overhead than the iPhone 3G having to do all the work itself.

Speaking of consuming less power, the iPhone (and Apps via the SDK), is also able to leverage all three of its location-based technologies in an elegant, escalating manner, using only what it needs and only when it needs it. If you only require location within a few blocks, cell and wifi are enough and there's no need to waste power spinning up the GPS. Need something spot on? GPS is there, passed on the information, and then powers down again when it's no longer needed.

Another drawback? So far, no turn-by-turn audible driving directions, but that may change.

Not everyone will need full aGPS. For some, the less they know about where they are, the better. But if you want to know exactly where you are, the iPhone 3G's aGPS will definitely appeal to you.

I know I want it. What about you?

Have something to say about this story? Leave a comment! Need help with something else? Ask in our forums!

Rene Ritchie

EiC of iMore, EP of Mobile Nations, Apple analyst, co-host of Debug, Iterate, Vector, Review, and MacBreak Weekly podcasts. Cook, grappler, photon wrangler. Follow him on Twitter and Google+.

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Reader comments

iPhone 3G: 5 Days and Counting Down to GPS!


I must say I get a tinge of jealousy every time the Instinct commercial comes to the point where the phone announces "Turn Right. Turn Left."
But then I realize it is an Instinct and then I feel better.

@ H22kai,
True, the Instinct has audible turn by turn directions, but what they fail to tell you is you pay at least 10 bucks extra a month for that feature. Hopefully AT&T and the iPhone won't gouge on GPS help.

Does the 3G have GPS capability without the need for Cell towers? For example if I find myself in the middle of nowhere and I don't have a cell signal will the GPS capable of still locating or is it going to be useless as well without a tower to "do the work" for it?

@ ethan:
Thanks! I never checked into that as I would never use Sprint. That makes me feel a lot better!!! Fingers crossed that Tom Tom comes soon (and is included in the data price).

I think what everybody keeps missing is that we don't have to wait for apple or att to provide the features that are missing on the iPhone. U want turn by turn directions? TomTom is already writing a version of their software for the iPhone. U want video capture? Hackers have already developed a video camera and can just as easily do it with the sdk. Mms, it can be done. Voice dial? It can be written.

@brandon. yes of course it will still work it just receives the sigal from a satellite. I WANT ONE NOW!!! :P

@ethan...i've already checked with AT&T and they are going to charge you $9.99 for GPS usage a month.

GPS is one of the BIG things I was holding out for. I've stuck with my VZW Treo 700p for the past year waiting for 3G and GPS and finally on Friday I'll get my iPhone fix!

I've said it before and I'll say it again: GPS is absolutely essential for me -- I get lost easily and my sense of direction is slowly but surely dying.

Actually, Sprint Navigation is included with all the Simply Everything plans you have to get with the Instinct.

The iPhone G3 ships with Google Maps. Google Maps is pretty much useless compared to TomTom or Garmin when it comes to GPS. It is just not practical. If I tried to pay attention to the Google Maps "directions" which are on screen and do not follow you as you go and have manual push button page turns, I would wreck my car. Between the lack of a practical GPS navigation system and the lack of flash I am extremely disappointed with my iPhone. I should have waited for the Instinct to come out.

The Instinct's GPS comes with the phone's plan for $69/mo. Try visiting Sprint's website next time...

Nexus One - Google competes with Apple iPhone That's right, humans -- We are bequeathing you bozos the complete write up on every nook and cranny of the NEXUS ONE. In case you've holding out under a rock, here's the breakdown of the 'phone. The HTC-built device executes Android 2.1 on a a 1GHz Snapdragon CPU, a 3.7-inch, 480 x 800 display, pulls in 512MB of ROM, 512MB of RAM, and a 4GB microSD card (expandible to 32GB). The phone is a T-Mobile device ( having in mind no 3G if you want to engage it to AT