Silicon Investor (SI) -- The First Internet Community

STOCKTALK

We've detected that you're using an ad content blocking browser plug-in or feature. Ads provide a critical source of revenue to the continued operation of Silicon Investor. We ask that you disable ad blocking while on Silicon Investor in the best interests of our community. If you are not using an ad blocker but are still receiving this message, make sure your browser's tracking protection is set to the 'standard' level.

Technology Stocks : Qualcomm Moderated Thread - please read rules before posting -- Ignore unavailable to you. Want to Upgrade?

To: rkral who wrote (23294)	6/1/2002 6:09:51 PM
From: pheilman_	Respond to of 196649

Ron, An absolute distance measurement from a transmitter to a receiver requires absolute timing at both. An error in time of just 1 microsecond leads to a 300 m uncertainty, exceeding the FCC requirement. As Clark has pointed out, with a 200 KHz bandwidth the timing uncertainty at the mobile is likely to be even larger. So, I am objecting to the reassuring narrowness of the error bands in the CPS site diagram. There really are no circles, until the third BTS is in communication with the mobile the location cannot be fixed. If my wife called 911 from her mobile, while bleeding profusely, I would prefer to have a working system for location, I don't think E-OTD works. I am long QCOM, and have spent a decade working on electronic warfare systems. I keep making the mistake of describing our time difference of arrival (TDOA) system rather than the one CPS is proposing. Ours was working with a non-cooperative transmitter. Side notes: I concede not to have known the shape of the curve. Have you been taking debating training from George H. Bush? (his zinger to Dukakis) The co-linear case is a bad problem when the mobile is not on the line, even with three BTSs, the error is very large. What have the Europeans got against GPS? It really works rather well, there is no charge for using the signals, must just be galling to use US military largesse. It is forcing them to come up with a system that requires a whole new set of fixed site base stations, the Location Measurement Unit, that doesn't even add voice capacity. With GPS disciplined oscillators at the existing base stations, the LMU expense could be avoided. Just following web links on the EOTD and the CTO of Cambridge is interesting. Peter Duffett-Smith did early work on location using FM commercial broadcasters. Looking at several patents, it still looks as though location requires three well sited base stations. Lots of Angle of Arrival (AoA) and other techniques presented. Paul