[82491] in North American Network Operators' Group
Re: Vonage Selects TCS For VoIP E911 Service
daemon@ATHENA.MIT.EDU (Andre Oppermann)
Wed Jul 20 06:27:21 2005
Date: Wed, 20 Jul 2005 12:26:54 +0200
From: Andre Oppermann <nanog-list@nrg4u.com>
To: Mikael Abrahamsson <swmike@swm.pp.se>
Cc: nanog@merit.edu
In-Reply-To: <Pine.LNX.4.62.0507201159390.3636@uplift.swm.pp.se>
Errors-To: owner-nanog@merit.edu
Mikael Abrahamsson wrote:
>
> On Wed, 20 Jul 2005, Andre Oppermann wrote:
>
>> To sum it up: Using GPS to geo-locate VoIP phones or adapters is
>> broken by design.
>
> No, it isn't. Relying on satellite connectivity to do so broken, but
> that's not how it works anymore. Did you even read the article regarding
> indoor GPS that I posted earlier in the thread?
I did but those ground based transmitters are only for improving accuracy
by sending you the position delta determined vs. real for that region. It
doesn't help if you don't receive a GPS signal. That ain't satellite radio
which is being terristrically re-broadcast.
For more information have a look the descriptions of these augumented GPS
systems:
http://en.wikipedia.org/wiki/GPS#Techniques_to_improve_GPS_accuracy
http://en.wikipedia.org/wiki/Trilateration
To sum it up: Without having good GPS reception you can't do trilateration
and without it you can't apply any accuracy improvements.
--
Andre
