aGPS

Dear phone, we're not in Akron!

Update: Nokia just pinged us to let us know they are "...aware of the issue and it has been addressed, but users may need to restart their phones to see the fix take effect." Moreover, this does not seem to be a Lumia 900 issue per se but rather related to AT&T's LTE towers. Evidently some Android users have had this problem too.

It looks like the Nokia Lumia 900 on AT&T is experiencing yet another odd and seemingly random bug these days. For some users, when they fire up a GPS application such as Maps, Local Scout, Foursquare (for checkins) or Yelp, they show up as being in Akron, Ohio despite not actually being there.

The issue first popped up in Nokia's support forums with two threads and a handful of users noting the problem. Another thread appeared here in the Windows Phone Central Forums as well. But to be honest, we had only received one email complaint on the matter from reader Alex T. and we had not seen this bug ourselves to verify--so off it went into the "quirks" pile for further investigation.

This week though as we're paling around with Rafael Rivera and Paul Thurrott in sunny San Francisco, both of their devices suddenly had this happen. First up was Thurrott who's phone just would not budge from the great state of Ohio. Despite soft-resets, some toggling and a boatload of swearing, there it stayed.

Later that night, Rivera's phone did the exact same thing when we were at Denny's. What was curious though was how both phones, even when placed next to each other, did not have the bug at the same time. Both Lumia 900s, both on AT&T, yet one worked and the other did not. (Our 900 was in tow but we were using the Focus 2 as our primary device this week).

We're not sure if this is related to AT&Ts network for aGPS, an issue with full GPS or maybe something in between. We have noticed that more folks seem to experience it on the West coast but that could just be sampling error. 

So we figured we would crowdsource this a bit and ask you if you've experienced this on your Lumia 900. And if so, what state are you in? Hit the poll below. (And for our international users, have you had something similar?).

 

Has your Lumia 900 erroneously positioned you in Akron, OH?
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We've talked about the differences between aGPS and GPS before, but we can now add another form of aGPS to the bunch: QuickGPS

QuickGPS is from Qualcomm (technically called gpsOneXTRA Assistance) and is an Internet-based form of aGPS or offline aGPS whereby your device, once a week, downloads a data file that has all the ephemeris data contained (file = packedephemeris.ee).  This data is good for 7 days and helps calculate your position faster without the need for an Internet connection at the moment of initiation (ala network-based aGPS).  "Cold starts" go from a minute or more to just seconds. Very cool.

HTC has been incorporating this into some of its devices lately (e.g. Touch Pro) and Palm has it on the GSM Treo Pro.  HTC calls it QuickGPS as it made a nice app to initiate the system (see above photo). 

But as usual, some of us were not invited to the party (e.g. Sprint Mogul, Touch, etc.) and the community has effectively taken matters into their own hands, hacking this onto various devices.  The latest is the Sprint/Alltel Treo Pro and we have to admit, it works like a charm. 

So if you want to join in and speed up your GPS system, feel free to browse those threads!  And remember: back up before you do so!  This also may not work on all devices--if you get "QuickGPS.exe' cannot be opened. Either it is not signed with a trusted certificate, or one of its components cannot be found. If the problem persists, try reinstalling or restoring this file." that would be you, sorry.

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Quick Tip: You May Not Want aGPS On

We've gone to great lengths to explain the differences between GPS and aGPS and also generally celebrated the arrival of full-on aGPS on many a carrier. One thing, though, if you have one of these fancy, aGPS phones, you may not necessarily want to have the thing on, because it could potentially make your GPS acquisition times worse.

The advice comes to us by way of MyTodayScreen and here's the nut of it: if you're using an unlocked device or an otherwise non-carrier-supported device, it's a good bet that turning on aGPS is going to lengthen your acquisition time as the assisted part of it tries (and fails) to get location information from the local tower. They ran into the issue using a TouchHD, where turning off aGPS sped up acquisition time significantly. I've had the same issue on the HTC s740 on AT&T: turning off aGPS made a big difference for me, too.

Yeah, sorry, it's not a simple situation (this stuff never is). Even if you are using a fully-supported device on its proper carrier and aGPS is up and running in your area, it's still one more potential point of failure. Just because things are getting better on the GPS front doesn't mean that Microsoft, manufacturers, and carriers don't have a long way to go to making location hardware simple.

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AT&T gives your GPS a boost

AT&T has flipped the switch on its Autonomous GPS service, which should help your aGPS enabled phone connect to the satellites much more quickly. (Surprisingly, AT&T hasn't had this enabled until now.)

"But Phil," you ask, "I already have GPS on my phone. What's aGPS going to do for me?"

To answer that question, we return to everyone's favorite WM Expert, Malatesta, who in January brought us a great tutorial on the kissin' cousins of the Global Positioning System.

Read GPS vs. aGPS: A Quick Tutorial.

Then step outside, fire up your favorite mapping app, and let us know in the comments if you can see a difference.

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One neat feature that we've mentioned recently in our Podcast was Palm's unique "Maps" program and Today Plugin, which is nicely tied into the phone's aGPS system.

Palm has always done a nice job in marrying the hardware to the software and instead of just slapping some GPS on the phone, they actually made it...well, useful and easy.

Here are a couple of interesting things gleaned from past scoops and the recently released user manual...

Read on for more details on the 800w's GPS capabilities...

Features:

  • Look up a contact's location directly from your Today screen (p240)
  • Find people, restaurants, movies, etc. using the GPS Today plugin (p182)
  • Map your current, recent, and street locations

It also appears that at least for some of these functions, it uses the much superior assisted-GPS system, meaning your current geographical location should happen within seconds, as opposed to the longer "cold start" of traditional GPS systems (read our GPS vs aGPS tutorial here). This should make it faster than the Sprint Touch, Mogul and Q9c which don't use the assistance servers out-of-the-box. Stay tuned for more details.

Basically how it works is while on the today screen, you can just type the name of your contact, hold down the center key and select the "Find" menu entry. The GPS will then map that contact's address directly on the screen.

The other unique feature involves the "Point of Interest" plugin which is sort of like having Microsoft's Live Search built right in to the Today screen. All you do is type in whatever you are looking for and hit "enter" and it will look up and map the info directly, all based on your aGPS coordinates.

That brings us finally to that last aspect. the program "Maps". Not much is currently known about this except it looks like Goolge Maps (but isn't?) and it is not Live Search, though we understand both programs will work with the device's built in GPS. This app appears to be a custom mapping program that is streamlined and tied closely to the OS, for seamless integration.

Either way, these "little features" look to be quite useful and and at this point, unique to the Palm Treo 800w.

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GPS vs. aGPS: A Quick Tutorial

With discussions and speculation about what features the new Treo 800w will have, the convoluted and very confusing issue of aGPS versus GPS naturally arises and which, if either, the 800w will include. So what is aGPS? How does it differ from real GPS if at all? We'll fill you in on the full skinny -- which sadly can be anything from "just e911" to "Better than standard GPS."

Read on to learn what all of these terms actually mean and what it means for Windows Mobile users in general as this technology spans CDMA and GSM across the U.S on every device.

aGPS vs. GPS: The Basics

Okay, first let's do the basic definitions: aGPS = assisted global positioning system, while just regular GPS is non-assisted.

So who's assisting and why does it matter? When you use a GPS system and you turn it on, it needs to find orbit and clock data for the relevant satellites, this in turn results in what is called TTFF, or Time To First Fix how long before you get your location pinpointed. This initial TTFF is often called a cold start and on SiRF III systems (the latest GPS systems available), it can take anywhere from 30 seconds to a couple of minutes to acquire a signal. That time is dependent on your location, amount of interference and horizon information: open fields are faster than canyons or urban environments where buildings can interfere with the satellite-receiver line of site.

But when you use assisted GPS this whole process is much faster. Very often cellular network towers have GPS receivers (or a base station nearby) and those receivers are constantly pulling down satellite information and computing the data. This data is then passed on to the cellular phone (when requested) and acts like a cheat since the relevant satellites to your location are already identified and all that GPS computations is handled by 3rd party computers. This is the result of such a system, to you the end user:

  • Faster location acquisition
  • Less processing power is required by the device
  • Saves battery life
  • Location acquisition indoors or in non-optimal environmental settings

Sprint describes how their system is supposed to work from their online FAQ:

Q: What is Assisted GPS? How do you find me if only two satellites are available?
A: To meet the defined industry standards, a precision location fix requires a minimum of three GPS measurements. The term "Assisted" refers to how Sprint network resources are used to provide a more robust measurement when only two satellites are visible.
  • Precision fix in tens of seconds.
  • Very High accuracy (typically 5m-50m).
  • Line of sight to three satellites is not required as in regular GPS technology, but two satellites must be visible for a precise AGPS fix.
  • GPS chipset required in device. (All Sprint phones sold since Jan 2002 have the GPS chipset. Contact your Sprint account representative for additional information.)

This is why many of us in the forums often cringe when someone suggests that having a standalone SiRFIII chip in a phone is preferable to an aGPS system, although the confusion is quite understandable and that brings us to our next point: the caveats.

Caveat #1: aGPS configurations

This story of aGPS so far seems fairly reasonable and straightforward, but alas it is not. See aGPS is not some monolithic, written-in-stone-standard. In fact, Qualcomm, who makes the most popular aGPS chips (called GPSOne) has four different possible configurations for aGPS. How aGPS is actually implemented on the device appears to be up to the device OEM/cellular carriers.

These four options are:

  • Standalone - Your handset has no connection to the network, and uses only the GPS satellite signals it can currently receive to try and establish a location.
  • MS Based - Your handset is connected to the network, and uses the GPS signals + a location signal from the network.
  • MS Assisted - Your handset is connected to the network, uses GPS signals + a location signal then relays its 'fix' to the server, which then uses the signal strength from your phone to the network towers to further plot your position. You can still maintain voice communication in this scenario, but not 'Internet/Network service' ie Web Browser, IM, streaming TV etc..
  • MS Assisted/Hybrid - Same as above, but network functionality remains. Normally only in areas with exceptional coverage.

Standalone mode is important. This means you do not need the carrier network at all to use GPS and usually you can install any GPS mapping software to boot. This is how the HTC Tilt and modern BlackBerries work and the Sprint Q9c (a review of which will be posted on WMExperts next week). Here there is virtually no difference between a standalone SiRFIII GPS system and a standalone (aka autonomous). The fact that the Sprint Q9c operates in standalone should be a sign of how Sprint plans to adopt aGPS systems in their Windows Mobile lineup (read here and here regarding possible updates for GPS for the Mogul and Touch). Interestingly, someone came up with a hack to enable the assistance servers for the Q9c to give all the benefits of a true aGPS system.

So which configuration of aGPS is important to how you can utilize the service. If it 100% relies on assistance-servers, then using it off-network is not an option, which may be the case with the BlackBerry 8830 (Sprint Worldphone):

Q  Does GPS work internationally?
A  No, the GPS chipset on the 8830 is disabled when the device is in GSM/GPRS mode due to Qualcomm requirement.

Caveat #2: The role of the mobile carriers

Now for the other shoe to drop: the carriers. Every modern cell phone has an aGPS chip on it because of the enhanced 911 requirement, which is also why you don't have many phones with a separate SiRFIII chip on board: it is redundant and expensive.

But on Sprint, Verizon and some other carriers like AT&T they have devices with aGPS on board that is not accessible to the end-user for any purpose except for e911 (like the ppc-6700 or the Treo 700wx). Now why this is the case is a matter of debate and a lot of speculation, which ranges from the carriers have purposefully disabled this feature to the APIs were not ready (API= Application Programming Interface) or maybe even a combination. Some have also suggested that these devices need an internal antenna plexed to the chip in order to gain a satellite signal, although since cheap flip phones on Sprint can do aGPS, this remains controversial. Regardless, the fact that simple flip phones could do aGPS for mapping and $500 WM phones cannot, rubbed many in the mobile community the wrong way.

The point of this caveat is that it is up to the carriers ultimately do decide on whether certain devices have:

That last option, for whatever reason, is currently the most common but it at least appears that the carriers (except for maybe Verizon who is truly draconian) are moving towards the more open system.

Wrapping Up

Hopefully you have learned how aGPS can mean everything from it does nothing except for 911 to it is superior to traditional GPS. Where new WM devices fall on that spectrum is an ongoing adventure, but hopefully you now have the knowledge to ask the right questions:

  • Is the aGPS autonomous?
  • It is locked down (e.g. hidden COM ports)?
  • Can it use assistance servers when < 3 satellites are available?

Having answers to those will allow you to better gauge what GPS or aGPS really means.

PS Feel free to bookmark or pass this article on to others to help dispel any confusion out there on the 'net ;-)

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