navigation. two sad jokes who leaves the table after everyone’s eaten? –a cannibal. why is the...
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Navigation
TWO SAD JOKES
• Who leaves the table after everyone’s eaten?– A cannibal.
• Why is the banana the most popular fruit?– Because it has appeal.
How do we know where we’re at?
You are here. Huh?
X
Before GPS…. Celestial navigation
• The pattern of stars and planets seen from Earth are constant in space. The celestial sphere.
• It is useful to be able to precisely specify positions on the celestial sphere.
So, a set of coordinates is used that is similar to latitude and longitude on the Earth.
The system of latitude and longitude was first suggested by Hipparchus, a Greek astronomer in the 2nd C. B.C.
• The North Celestial Pole is the point on the celestial sphere directly above the Earth's North Pole.
Similarly, the South Celestial Pole is directly above the Earth's South Pole.
• The star Polaris, in the constellation Ursa Minor, is located very close to the North Celestial Pole.
Polaris is therefore also called the North Star.
More accurate: Longitude & Latitude
Longitude:Angular distance on the
earth's surface, measured east or west from the prime meridian at Greenwich, England.
• Lines of longitude are blue (east) and red (west) in the drawing.
LatitudeThe distance north or south
of the earth's equator. 0 degrees latitude is the equator, the "belt" that goes around the "waist" of the earth. 90 degrees north is the North Pole and 90 degrees south is the South Pole.
• Lines of latitude are blue (north) and red (south) in the drawing.
Tools of the trade…
• Sexton: measures the angle between celestial bodies and the Earth to determine position.
• Compass: Point to magnetic North, so you can follow a course by knowing our position in relation to North.
• Loran C: radio transmissions from set positions on the surface of the Earth, that triangulate to give you a position.
• GPS: is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations.
Sexton• a device that
measures the angle between two objects. It uses the position of stars to find it’s latitude, longitude.
Compass
Loran C
• LORAN-C was originally developed to provide radio-navigation service for U.S. coastal waters and was later expanded to include complete coverage of the continental U.S. as well as most of Alaska. Twenty-four U.S. LORAN-C stations work in partnership with Canadian and Russian stations to provide coverage in Canadian waters and in the Bering Sea. LORAN-C provides better than 0.25 nautical mile absolute accuracy for suitably equipped users within the published areas.
What is Loran-C?• Loran-C is a low frequency/long wave electronic position fixing
system using radio signals transmissions @ 100 KHz from 3 or more transmitters, linked in a chain. It gives a latitude and longitude readout position to marine, aero and land receivers.
The Global Positioning System (GPS)
• is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations.
• GPS uses these "man-made stars" as reference points to calculate
positions accurate to a matter of meters. In fact, with advanced forms of GPS you can make measurements to better than a centimeter!
• In a sense it's like giving every square meter on the planet a unique address.
• GPS receivers have been miniaturized to just a few integrated circuits
and so are becoming very economical. And that makes the technology accessible to virtually everyone.
• These days GPS is finding its way into cars, boats, planes,
construction equipment, movie making gear, farm machinery, even laptop computers.
Coordinates given in Longitude, Latitude
Longitude:
40 E
Latitude:
65 NNorth
South
EastWest
Mapping activity
• http://olc.spsd.sk.ca/DE/k9mod/Mapskill/mod3fl5.swf
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