Subject:
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Re: GPS
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 4 Jan 2001 22:14:09 GMT
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Original-From:
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John A. Tamplin <jat@jaet#NoSpam#.org>
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Viewed:
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676 times
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On Thu, 4 Jan 2001, Vihung Marathe wrote:
> OK. This is probably a bit off-topic ... but I am sure you will find
> this interesting ...
>
> I recently rented a car from Hertz with the NeverLost system - GPS
> Receiver, Street Maps and Business/Tourist directory built into one.
> Apart from the fact that I found this EXTREMELY useful (so useful in
> fact that I am looking for a similar system to install in my car), I
> also found it very accurate. Far more accurate than the 30 meter
> resolution that civilian GPS is supposed to offer.
>
> I was pondering over how this can be for most of my trip ... until I
> drove somewhere where it could not find any satellites (blocked off by
> buildings and such). As I moved, more and more satellites came into view
> ... but it would not show my position on the map until it could see 6
> (it had an indicator showing how many were in view in place of the map).
>
> Now I am not sure about this ... but if I remember my high school
> geometry correctly (and I think I remember reading this in an article
> about GPS some time ago when it first became popular) ... you only need
> three satellites in view to pinpoint your location. If that is the case,
> then do you get better resolution with more satellites?
>
> The reason I ask this here is that some time ago, I was wondering if GPS
> could be used to pinpoint the position of a Lego robot - but then
> realised that it would be of no use within a room, because the room
> would be smaller than 30m that GPS can resolve. However, if it is
> possible to get more info using more satellites, then maybe we can think
> about it
The reason you are getting better resolution is the US Government turned
off selective availability (the random noise inserted into the timebase,
then encrypted so military applications can use it). They reserve the
right to turn it back on in a time of war.
John A. Tamplin jat@jaet.org
770/436-5387 HOME 4116 Manson Ave
770/431-9459 FAX Smyrna, GA 30082-3723
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Message is in Reply To:
 | | GPS
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| OK. This is probably a bit off-topic ... but I am sure you will find this interesting ... I recently rented a car from Hertz with the NeverLost system - GPS Receiver, Street Maps and Business/Tourist directory built into one. Apart from the fact (...) (24 years ago, 4-Jan-01, to lugnet.robotics)
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