Week 5 GPS & Microwaves

Question 1

what does a GPS receiver need to determine its location

Answer 1

signal from at least 4 satellites

Question 2

how does trilateration positioning method work

Answer 2

determine the relative location of points by measurements of distances using geometry of spheres or triangles

Question 3

how does trilateration differ from triangulation

Answer 3

trilateration does not involve measurement of angles

Question 4

why does GPS need 4 satellites

Answer 4

in works in spacetime which has 4 dimensions

Question 5

give at least 2 sources of inaccuracies in GPS

Answer 5

1 Selective Availability
2 Satellite Geometry
3 Satellite Orbits
4 Multipath effects
5 Atmospheric effect
6 Clock inaccuracies (relative effects)

Question 6

why is relativity a source of error for GPS

Answer 6

the speed of light is a very large value in comparison to the distances being measured so the estimated distances are very sensitive to errors in the clock from time dilation

Question 7

why is 2.45GHz an appropriate frequency for microwaves

Answer 7

it is the right balance of low and high frequency in order to penetrate the food to cook central parts and high enough to properly cook food