Verizon wireless - Re: Apple iPhone is GSM

Author

Re: Apple iPhone is GSM - GPS ?

JDa™©

2007-07-18, 10:33 am

karlkrandall@sbcglob
al.net wrote:
> On Tue, 09 Jan 2007 15:38:34 -0800, SMS <scharf.steven@geemail.com>
> wrote:
>
>
>
>
> Ummm.. It's also WiFi 802.11c and g
>

Looking through the spec's, theres no reference to GPS.
Isn't GPS *required* by the FCC on all new phones, so to
be compatible with new 911 location services?

If its not there, how did they get around not including GPS?

Scott Ehrlich

2007-07-18, 10:33 am

In article <m76dnUp1ps8- vgPbnZ2dnUVZ_sC3nZ2d
@comcast.com>,
Bill Marriott <wjm@wjm.org> wrote:
>There is a difference between the GPS that can be used to control one of
>those magic map and routing systems versus the locator technology mandated
>by E911. I'm not sure about the tech details, but my Treo 700p has a little
>crosshair icon on all the time and is compatible with Sprint's "family
>locator" feature, yet I can't use the TeleNav feature without the purchase
>of additional hardware.
>
>
>

Verizon Wireless, and possibly Sprint, via CDMA, use aGPS (*a*ssisted
GPS). It works with the tower to obtain and remain updated of your
location. Thus, it is not a truly self-contained GPS that a third-party
program can work with for directions. It is also possible that the GPS
receiver *is* capable of doing this but Verizon Wireless and/or Sprint may
have disabled that feature.

Scott

none

2007-07-18, 12:33 pm

Todd Allcock < elecconnec@AmericaOn
Line.com> wrote:

>
> No- SOME way to locate the phone if it calls 911 is required, but it
> doesn't have to have a "GPS." AT&T and other GSM carriers use a tower-
> location system (a sort of advanced version of triangulation.)
>
> This means AT&T knows where the phone is, but the phone doesn't. A few
> GSM phones have actual satellite GPS modules built in (HP 6915, Nokia N95)
> but the iPhone isn't one of them.
>
> While CDMA carriers (like Sprint annd Verizon) use a GPS-based system
> with a bit more accuracy, theirs is also network dependant- their phones
> don't know where they are either, unless you pay to receive that
> information from the carrier.

how it works is here:

http://people.howstuffworks.com/9-1-13.htm

Bob F.

2007-07-18, 3:33 pm

>
> how it works is here:
>
> http://people.howstuffworks.com/9-1-13.htm

There is an improvement on how this works but I am not sure which providers
implements it.

If you ever used a GPS (non-radio) device, you have noticed it takes several
minutes for the device to find you when first turned on. This is
problematic for a 911 solution. So in order to help this, the cellular
sight also has a GPS receiver in it and always has the preliminary data
ready when a cellphone calls in. If you turn your radio on and call
911(from a cold start), the cell sight sends the radio the preliminaries,
i,e, time, lat/lon map offset, all viewable satellite locations and other
data I can't remember. Then the cell phone can bypass this "setup and
finding" step and go right to calculating it's position step. Then it sends
it in. This cut off minutes of set up time which could be critical for a
911 call.

BTW, the GPS receivers in cell phones use for 911 purposes are cut down
versions of full receivers. They are intended to be activated for only
seconds and then go to sleep. Battery power is the issue. There may be
other cellphone GPS receivers capable of staying on for longer times but
recognize that these are more full blown GPS receivers, serve a different
market (tracking) and are not required for the 911 mandate. It will cost
you battery life when activated.

r. Bob F.

John Navas

2007-07-18, 3:33 pm

On Wed, 18 Jul 2007 14:43:13 -0400, "Bob F." <bob@N0ZPAMfurtaw.com>
wrote in < Y8CdnSNtYoaQwgPbnZ2d
nUVZ_jCdnZ2d@comcast
.com>:

>If you ever used a GPS (non-radio) device, you have noticed it takes several
>minutes for the device to find you when first turned on. This is
>problematic for a 911 solution. So in order to help this, the cellular
>sight also has a GPS receiver in it and always has the preliminary data
>ready when a cellphone calls in. If you turn your radio on and call
>911(from a cold start), the cell sight sends the radio the preliminaries,
>i,e, time, lat/lon map offset, all viewable satellite locations and other
>data I can't remember. Then the cell phone can bypass this "setup and
>finding" step and go right to calculating it's position step. Then it sends
>it in. This cut off minutes of set up time which could be critical for a
>911 call.

Assisted GPS as used in most handsets is actually quite a bit different
in that the assistance server computes position solutions, leaving the
GPS receiver in the handset with the sole job of collecting range
measurements.

--
Best regards, FAQ FOR CINGULAR WIRELESS:
John Navas <http://en.wikibooks.org/wiki/ Cingu...less_FA
Q>

Bob F.

2007-07-18, 3:33 pm

"John Navas" < spamfilter1@navasgro
up.com> wrote in message
news:17os931tgsopdgn
8vb6opf21fpfbrbfrk5@
4ax.com...
> On Wed, 18 Jul 2007 14:43:13 -0400, "Bob F." <bob@N0ZPAMfurtaw.com>
> wrote in < Y8CdnSNtYoaQwgPbnZ2d
nUVZ_jCdnZ2d@comcast
.com>:
>
>
> Assisted GPS as used in most handsets is actually quite a bit different
> in that the assistance server computes position solutions, leaving the
> GPS receiver in the handset with the sole job of collecting range
> measurements.
>
> --
> Best regards, FAQ FOR CINGULAR WIRELESS:
> John Navas <http://en.wikibooks.org/wiki/ Cingu...less_FA
Q>

Why and how would a GPS receiver collect "range measurements". I think what
you are talking about is "location assist" where trilateration is used to
find the handheld. No GPS device required in the handheld in this case. I
believe this is the most popular implementation (cheapest).

r, Bob F.

Dennis Ferguson

2007-07-18, 10:33 pm

On 2007-07-18, Bob F. <bob@N0ZPAMfurtaw.com> wrote:
> "John Navas" < spamfilter1@navasgro
up.com> wrote:
>
> Why and how would a GPS receiver collect "range measurements". I think what
> you are talking about is "location assist" where trilateration is used to
> find the handheld. No GPS device required in the handheld in this case. I
> believe this is the most popular implementation (cheapest).

What GPS receivers measure are the arrival times of signals from the
GPS satellites. The signals from the GPS satellites are DSSS, and the
arrival times are measured by observing the time offset at which the
receiver finds precise code alignment (arrival times of signals from
CDMA towers, which are also DSSS, can be measured in exactly the same
way).

A CDMA phone is closely time-synchronized to the tower it is homed to
(which in turn is closely time-synchronized to GPS time) since CDMA
requires this. When the base station wants a position fix from the
phone it tells the phone the satellite PRNG codes it should listen for
and the approximate arrival times it should expect those signals at
(since the phone is close to the tower the values observed from the
tower will be nearly the same). This eliminates the need for the phone
to do its own satellite acquisition. The phone makes precise measurements
of any of those GPS signals it can hear, along with measurements of tower
signals, and sends the arrival times of all of these back to the network.
A computer in the network uses all the GPS and tower data returned
to come up with a best estimate of the phone's position; the phone
doesn't need to be aware of any of the additional data it would need
to come up with a position fix on its own.

Note that the phone doesn't need to know anything about GPS satellite
locations, or tower locations, to do this, nor is it ever aware of
its own position. It just makes ToA measurements of the signals it is
told to look for, both GPS and tower, and sends them back; the network
does the heavy lifting. Also note that GPS and tower positioning data
aren't processed separately; if all the phone can hear is one tower and
two GPS satellites, all the arrival time data is used to compute a
positioning solution better than either tower or GPS data alone could
provide.

Dennis Ferguson

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