Subject:
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Re: GLOBAL POSITIONING SYSTEM
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Thu, 21 Oct 1999 16:13:31 GMT
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Original-From:
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Curt Mills, WE7U <hacker@/AntiSpam/tc.fluke.com>
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Viewed:
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763 times
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On Wed, 20 Oct 1999, William Ho wrote:
> I learned that somebody has successfully connected GARMIN GPS to HB.
> If I am not wrong , this GPS is not be able to receive any signal in
> building. If this the case, GPS is only good for outdoor robotics.
> Another thing is about the accuracy of the GPS, it is about 1 to 15
> feet which I think is not good for detail mapping.
Yes, I have done it, perhaps others. I use mine nearly every day
connected to a GPS, but it has nothing to do with robotics.
You're a bit off on your accuracy though, the spec actually says
you'll be within 100 meters 95% of the time. I think it says you'll
be within 300 meters the other 5%, but it's been a while since I read
the spec.
You'll typically get within 60 meters or so in reality. If you connect
a DGPS receiver to your GPS and are within range of a transmitting station
you can cut it down to 1-10 meters accuracy. Whatever you do, never
believe the EPE figure on a Garmin. It's worthless. If you want a
good accuracy figure, there's a way to power up a Garmin (hitting a
certain sequence of keys) where you'll see the HDOP figure on the
first page. That figure CAN be believed. You can also read the
inside temperature of the unit and the battery voltage in that mode,
among other things.
GPS typically cannot receive signals inside buildings, unless you're
very lucky in the type and density of the building material. I can
receive signals most of the time inside my house, but it is a one-story
wood structure. I still get some blockage. Oh yea, water blocks it
also. I think I heard something like 1/8" or 1/4" of water will
effectively block the 1.5 GHz GPS signals.
Curt Mills, WE7U hacker.NO_*SPAM@tc.fluke.com
Senior Methods Engineer/SysAdmin
"Lotto: A tax on people who are bad at math." -- unknown
"Windows: Microsoft's tax on computer illiterates." -- WE7U
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Message is in Reply To:
 | | GLOBAL POSITIONING SYSTEM
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| I learned that somebody has successfully connected GARMIN GPS to HB. If I am not wrong , this GPS is not be able to receive any signal in building. If this the case, GPS is only good for outdoor robotics. Another thing is about the accuracy of the (...) (25 years ago, 20-Oct-99, to lugnet.robotics.handyboard)
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