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