Vonage Selects TCS For VoIP E911 Service

Wed Jul 20 10:26:54 UTC 2005

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