AGPS, cellphones and LBS services

[xenophon]

With many cellphones apparently already capable of AGPS (e911 uses it) and SnapTrak type of technology, why are there not already location-based services developed? It would seem smartphones, such as Treo 650 and PocketPC phones that already have AGPS would not need a separate GPS device.

Shouldn't existing GPS/mapping software written for PDAs work on PDA smartphones w/out the need to separate GPS hardware such as a bluetooth GPS device?

What is the future of cellphone-based LBS and how it alter the future of GPS?

[lbendlin]

There are some misconceptions about AGPS - you do still need the GPS antenna in the phone. AGPS just helps you to get the basic data (Almanac, Ephemeris) in a much quicker way, greatly reducing the computing effort and the time to fix.

However, a phone without GPS antenna can only be located as accurately as the cellular network stability permits (by triangulation of the cellular radio signals from different towers) and this will only give you 150-250 metres accuracy at best.

This is sufficient for LBS and maybe for some of the navigation tasks (like accident avoids), but not for the street navigation itself.

You do need GPS hardware in the phone if you want accuracy in the 5-15 metres range.

Here's some more detail
http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=12287
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Lutz

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[xenophon]

I'm confused with what SnapTrak can do. It claims to be AGPS yet have 10m or better accuracy and works indoors. They claim there are already 15 million CDMA phones out there with the technology. That's 80% of the CDMA install base. Does the Treo 650 have this?

http://www.snaptrack.com/technology/index.jsp


If phones already have this built in, especially PDA phones, I'd think existing GPS PDA software could access this instead of needing an external GPS device for a PDA phone.

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