| Steve & Susan 2005-05-24, 5:58 pm |
| On Sun, 22 May 2005 10:38:58 -0700, John Nelson
<DieSpammerDie@njabl.org> wrote:
>First of all, the notion that the location of a cell phone caller can be
>determined quickly and reliably (without the use of GPS enabled
>handsets) is a MYTH.
Even WITH GPS, there are severe limitations to cellular ALI. One that
is consistantly ignored is the location of an iindividual inside a
shopping mall or highrise building where there is attenuation of
signal preventing the use of the GPS constellation. Or, for that
matter a situation which requires a Z coordinate.
>Yes, triangulation can narrow down the general
>vicinity (depending greatly on the density of sites within the area) but
>that's a far cry from "1234 Main Street, Apt. 3-G". So let us set aside
>the argument that cell phones provide E911 functionality. Clearly, they
>do not.
Agreed. The figure of accuracy was another ambitious goal from the FCC
where the technology was not quite as reliable as the lawyers expected
(just like the migration of land mobile services to 6.25 kHz occupied
bandwidth when they aren't even ready to go to 12.5 kHz). Perhaps they
should have asked the one or two engineers in their organization that
have not attritioned out just yet. Positioning by means of RF can be
slewed by a number of factors no one has control over, such as
multipath in an urban environment, propagation over large bodies of
water, ground conductivity, relative humidity, etc.
I sell the idea by the notion of "aiming low." When the lofty goals
are set aside, knowing "something" about where a caller is located is
better than knowing "nothing."
Now, all I and other 9-1-1 coordinators who are not fortunate to be
leaders in the field working in well-funded/ high profile environments
need (besides a better regulatory environment and politicians who take
9-1-1 more seriously) is more than one site in our outlying wireless
coverage so that there can be another point to triangulate from.
Steve
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