January 23, 2005

Can You Find Me Now?

First of all, I have a philosophical question. If the police had known that these idjits were tweakers, would it have been appropriate, in light of Warren v District of Columbia, to thell them "You've buttered your bread now sleep in it"?

I heard the story on the radio (and Michele was kind enough to find it on line for me. The reason the story caught my attention is that I will be spending Monday driving around suburban Waukesha county calling 911 to determine how accurately the newly installed system enables them to locate me. The news report about the lost meth heads says that their 911 call "had bounced off different cellular telephone towers" which is not an accurate description of how things work. Calls are received by the antennas serving the radios at the site (towers for short) and shouldn't bounce off anything. I know of only two locations around Milwaukee where reflection determines the sector in which a call appears. I would interpret that quote to indicate that said idjits were using a GSM phone where the provider and PSAP have implemented phase one of E911, which provides only the sector on which the call originated. Because a GSM phone selects whichever sector it receives the strongest signal from, and because this is influenced by terrain and elevation as well as distance, this is only of limited help in locating the caller. In the CDMA world a call is carried by multiple sites, and thus triangulation is a simple matter of programming, but a GSM provider has to invest in a complex system to meet E911 requirements. My task is going to be to determine whether that investment, and the county's investment , has been effective. Whether the investment is worthwhile will depend on who is saved as a result.

Posted by triticale at January 23, 2005 12:05 AM
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