[Geowanking] Re: E911 // cellular trilateration accuracy

[Debi Jones]

Dan those are GPS solutions.  Nextel and Boost Mobile who have deployed
A-GPS also provide cellid as a fall back.  There are 2 other distinctions
for GPS determined location and those are Quick Fix or Full Fix.  Full Fix
is more accurate, but takes anywhere from 30 secs to 3 mins to deliver.  A
Quck Fix takes at least 10 secs.  You must be outdoors for any of the
consumer GPS solutions to return a fix.  I was 3 feet inside a Starbucks and
the Boost phone I was using had to revert to cellid.  And if you're mobile
trying to get some information a 10 sec wait fills like an enternity.  More
times than not the consumer implementation of GPS fails and reverts to
cellid which is more useful than no location, but just barely depending on
the application.  Enterprise implementations of location services from
Sprint and Nextel are much better, but there's substantial revenue in those
solutions.

Verizon is in testing with it's location service, but unlikely to make it
available to developers before the end of the year.

Other solutions around cellid can be exposed by the user if you have a S60
phone.  You can write or download a python script to reveal the cellid lat,
long info already stored in your handset.  There may be some other
grassroots solutions for revealing location info already in the handset.

P.S. I dig what you guys at socialight are doing, btw.

...Debi

On 4/12/06, Dan Melinger <dan at socialight.com> wrote:
>
> Out of the larger carriers in the US, it's my understanding that Verizon
> and Sprint are using A-GPS and the GSM guys, T-Mobile and Cingular are using
> alternative technology like Uplink Time Difference of Arrival
> (U-TDOA) technology provided by TruePosition.
>
> A-GPS requires a chip in the phone while U-TDOA doesn't.
>
>
> On Apr 12, 2006, at 12:46 PM, Anthony Townsend wrote:
>
> It's the FCC not the FAA, and my understanding is that none of the US
> carriers are using tower triangluation (EOTD or other variants) because of
> the cost of network upgrades. Instead they are pushing to cost to you, the
> consumer, in the form of A-GPS equipped handsets.
>
>
>
> roger at sylvanascent.com (roger at sylvanascent.com) wrote @ 4/10/06 9:35 AM:
>
> I think this is a great question. I talked to a gentleman from South
> Africa
> last year at Where 2 who claimed to be a GSM expert. He said that GSM can
> locate you within something like 3 meters with no GPS support just using
> the towers, and that this was built into the GSM spec. He spoke of a case
> in South Africa where they located some sort of criminal using the GSM
> records.
>
> He said that CDMA on the other hand, cannot locate so precisely.
>
> So, to me, A-GPS was designed to make CDMA users locatable to the same
> degree as GSM.
>
> As an aside, does anyone know which type of cell phones are more lethal?
>
> Roger
>
> Original Message:
> -----------------
> From: Ian | Urban Mapping ian at urbanmapping.com
> Date: Mon, 10 Apr 2006 01:42:23 -0400
> To: geowanking at lists.burri.to
> Subject: [Geowanking] E911 // cellular trilateration accuracy
>
>
> At the risk of asking (another) obvious question, I continue my naïve
> streak
> on this listserv…
>
>
>
> I've heard very different reports of how accurate cellphone tracking
> is—the
> FAA mandates something like 50% of calls must be traceable to within a
> range
> of 30m but I've heard some mobile pros say they've heard of it getting as
> good as several feet. Obviously this varies depending on geography (urban,
> rural, topography), but does anybody have any idea how the US wireless
> carriers stack up? And how does this compare to phones with GPS?
>
>
>
>
>
> Ian White  ::  Urban Mapping LLC  ::   <mailto:ian at urbanmapping.com<ian at urbanmapping.com>
> >
> ian at urbanmapping.com
>
> 120 West 45th Street  20th Floor  ::  New York  NY  10036
>
> Tel.212.242.8267  :: Fax.866.385.8266  ::  www.urbanmapping.com
>
>
>
>
>
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> | dan melinger
>
> | kamida :: socialight
>
>
> | email dan at socialight.com
>
> | web http://socialight.com
>
> | office +1 212 561 5155
>
> | cell +1 917 494 5856
>
> | skype melinger
>
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