Turn in Lab 2

• Put your name, section, and perm number on your answer sheet.

Lab 3: Land Navigation (1)

Yingjie Hu

Three North

• True North (N)• Magnetic North (MN)• Grid North (GN)

How to measure the direction between two points?

• Azimuth• Back azimuth• Bearing• Back bearing

How to describe the direction between two points?

• Read the part 2 of the instruction file, and figure out what are the definitions of the four concepts. (5 minutes)

A

B

Azimuth

• The direction of two points referring to the North.– Magnetic Azimuth– True Azimuth

A

B

North

Azimuth

Back Azimuth

• If forward azimuth is more than 180, back azimuth equals forward azimuth subtract 180

• If forward azimuth is less than 180, back azimuth equals forward azimuth plus 180– When azimuth = 30, back azimuth?– When azimuth = 220?

Bearing

• Another way to describe the direction of two points.– Baseline (N or S)– Angle between the baseline and direction– Direction of travel– E.g. N30W, S18E…

Bearing

A

B

North Azimuth = 120, how about its bearing?

S

EW

S60E

Back bearing

• Bearing can be calculated from azimuth• Back bearing can be calculated from back

azimuth• When azimuth = 30, how about back azimuth,

bearing, and back bearing?

Compass

Compass

The magnetic needle always points at magnetic north, not the true north

How to measure azimuth on a map?

1. Orient the map (make the magnetic north of the map in accordance with the magnetic north of the real world)

2. Identify the direction between two points.3. Use compass to measure the azimuth

Assignment

• This is a two-week lab. You only need to finish part1 to part 3 this week. And you do not need to turn in your homework next week.

• Please return the compass and map after the class.

• If you need to draw on the map, please use pencil and erase the drawing before returning it.