|
Cellular forums Home > Archive > Cingular cell phone service > April 2007 > Re: 911 Call location accuracy
You are viewing an archived Text-only version of the thread.
To view this thread in it's original format and/or if you want to reply to
this thread please [click here]
| Author |
Re: 911 Call location accuracy
|
|
|
| I'm not knocking or judging one system over the other, just referencing the
MSNBC article. I did read John's referenced link for additional
information. I realize (older) ATTWS phones can be used with the service.
The U-TDOA does reference "advanced triangulation", but I'm not sure I fully
understand this. I also realize Verizon's system may be poorer in
metropolitan areas.
I have been a happy ATT/Cingular customer for many years and have no plans
to change. Just trying to be informed.
Thanks.
"John Navas" < spamfilter1@navasgro
up.com> wrote in message
news:8fd9331s7r81249
66ssju3mb34p2j6cahi@
4ax.com...
> On Sun, 29 Apr 2007 00:09:37 -0600, Todd Allcock
> < elecconnec@AmericaOn
Line.com> wrote in
> < 46342a5d$0$16307$882
60bb3@free.teranews.com>:
>
>
>
> It's also dead wrong, like the rest of his anti-GSM mantra, endlessly
> trolled in GSM newsgroups. He's obviously got way too much free time.
> ;)
>
> --
> Best regards, FAQ FOR CINGULAR WIRELESS:
> John Navas <http://en.wikibooks.org/wiki/ Cingu...less_FA
Q>
| |
|
| al wrote:
> I'm not knocking or judging one system over the other, just referencing the
> MSNBC article. I did read John's referenced link for additional
> information. I realize (older) ATTWS phones can be used with the service.
> The U-TDOA does reference "advanced triangulation", but I'm not sure I fully
> understand this. I also realize Verizon's system may be poorer in
> metropolitan areas.
Actually it's not poorer, because it doesn't depend solely on GPS, it's
a hybrid system. It's far more accurate than the U-TDOA system.
The big advantage of U-TDOA is that it doesn't require a handset with a
GPS receiver. The trade-off is that it's less accurate. OTOH, it's
accurate enough for most intents and purposes, including E-911, but it's
not accurate enough for some location based services.
The GSM carriers in Europe are implementing similar systems to Snaptrack
because they want to offer location based services. Cingular has also
stated that they will roll out such a hybrid system. Cingular does offer
TeleNav, but TeleNav is not a hybrid system, it's strictly GPS based.
The hybrid systems are better because they work even indoors.
| |
|
| Sorry for the repost. I forgot to include alt.cellular.attws as we're
supposed to be doing.
al wrote:
> I'm not knocking or judging one system over the other, just
referencing the MSNBC article. I did read John's referenced link for
additional information. I realize (older) ATTWS phones can be used
with the service. The U-TDOA does reference "advanced triangulation",
but I'm not sure I fully understand this. I also realize Verizon's
system may be poorer in metropolitan areas.
Actually it's not poorer, because it doesn't depend solely on GPS, it's
a hybrid system. It's far more accurate than the U-TDOA system.
The big advantage of U-TDOA is that it doesn't require a handset with a
GPS receiver. The trade-off is that it's less accurate. OTOH, it's
accurate enough for most intents and purposes, including E-911, but it's
not accurate enough for some location based services.
The GSM carriers in Europe are implementing similar systems to Snaptrack
because they want to offer location based services. Cingular has also
stated that they will roll out such a hybrid system. Cingular does offer
TeleNav, but TeleNav is not a hybrid system, it's strictly GPS based.
The hybrid systems are better because they work even indoors.
[Copied to alt.cellular.attws. Please post all alt.cellular.cingular
posts to alt.cellular.attws as well. The Cingular name is going away,
and alt.cellular.attws is the proper venue for posts regarding AT&T's
Wireless Service.]
| |
| John Navas 2007-04-30, 10:33 pm |
| On Mon, 30 Apr 2007 00:37:19 -0600, Todd Allcock
< elecconnec@AmericaOn
Line.com> wrote in
< 46358280$0$16361$882
60bb3@free.teranews.com>:
>At 29 Apr 2007 19:09:03 -0700 al wrote:
>fully
>
>From what I understand, the system estimates the distance the phone is
>from the towers to allow "triangulation" with two towers instead of three.
It actually uses reception angle. With only two towers, timing alone
results in two possible position solutions. Angle data is used to
select one of the possible locations.
>
>I'm not sure that's necessarily true, since they can use triangultion
>when satellite data isn't available, so in theory, when the satellite
>data is available it works better, and when not, it works like Cingular's
>system.
CDMA2000 systems actually have to fall back to Enhanced Cell-ID, which
is substantially less accurate than U-TDOA with GSM.
--
Best regards, FAQ FOR CINGULAR WIRELESS:
John Navas <http://en.wikibooks.org/wiki/ Cingu...less_FA
Q>
|
|
|
|
|