GPS Basics

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GPS Basics

• 2007 NCSTA Institute

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Interesting revelations en route to teaching the
use of GPS receivers to middle schoolers

• Most students (and a good number of adults) do
  not have a good grasp of the concepts of latitude
  and longitude.
• Following a GPS without at least some map-reading
  ability can be trouble.
• Many folks have an interesting concept of how GPS
  units work.

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Three Questions to Build From

• Where were you born?
• Where was your most favorite vacation?
• Where is the furthest away from home you have
  ever been?

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Why Latitude Longitude?(Location. Location.
Location.)

• If we wanted to meet in Barcelona for a cold
  beverage, how best could we pinpoint a location?
  How about in NYC? Kansas?
• If we wanted to plot attributes (rainfall
  amounts, elevation, land use) onto a GIS map, how
  best could we pinpoint each location?

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Latitude Longitude create a grid system which
gives every physical location its own specific
name or marker.
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Latitude Longitude create a grid system which
gives every physical location its own specific
name or marker.

• As Long As You Include the Direction!!

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The Dilemma with Degrees

• 36 Degrees North, 80 Degrees West
• Hey! Where are you!
• Im in Virginia. Where are you?
• High Point.
• Oh
• With Degrees only, we can be precise to 69 miles.

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The Solution

• Degrees, Minutes, Seconds
• 36 23 19
• OR
• Degrees, Minutes, Decimals
• 36 23.317
• With 1000ths of Minute, we can be
• precise to a matter of meters.

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How does this System work?
With solid signal from one satellite, the
receiver knows it is a given distance from the
satellite, but it does not know what direction.
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With solid signal from two satellites, the
receiver knows it can only be at those locations
that meet both distance criteria...
(intersections of circles)
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So with solid signal from three satellites, our
receiver can pinpoint its location and give us an
accurate latitude longitude. . Right????
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Darn Topography
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Contact Info

• Feel Free to Contact Me with any Questions
• Kevin Moore
• Betsy-Jeff Penn 4H Education Center
• 336-349-9445
• kevin_moore_at_ncsu.edu
• www.bjpenn4h.org