Ren R 201 Midterm 1

Front 1

Technology

Back 1

The collection of tools,including machinery, modifications,arrangements and procedures used byhumans.

Front 2

Relative Direction/Position

Back 2

Example: "In front of me"

Front 3

Absolute Direction/Position

Back 3

Example: "North of that building"

Front 4

GPS

Back 4

A space-based satellite navigationsystem that provides location andtime information in all weatherconditions, anywhere on or nearthe Earth where there is anunobstructed line of sight to fouror more GPS satellites.

Front 5

Direction

Back 5

Relative position of one point or object in relation to another point or object. Can be relative or absolute.

Front 6

Position

Back 6

Spatial location of an entity. Can be relative or absolute.

Front 7

Compass

Back 7

A lightweight magnet, generallya magnetized needle, ona free rotating pivot thataligns itself to point tothe Earth’s magneticpoles.

Front 8

Magnetic Declination

Back 8

The angle between magnetic north (where thecompass points) and true north (the directionof a meridian line towards the geographicNorth Pole).

Front 9

Positive Declination

Back 9

When magnetic north iseast of true north; the needle is deflected tothe right.

Front 10

Negative Declination

Back 10

When magnetic north is west of true north; the compass needle is deflected to the left.

Front 11

True North

Back 11

The direction of the North Pole.

Front 12

Magnetic North

Back 12

The direction of the magnetic North Pole.

Front 13

Grid North

Back 13

A navigational term referringto the direction northwards along thegrid lines of a map projection.

Front 14

Magnetic Inclination

Back 14

The angle made with the horizontalby the compass needle of avertically held compass.

Front 15

Secular Variation

Back 15

Declination changes with time caused by variations in theflow of molten iron in Earth's outer core, resulting in changesin the orientation of Earth's magnetic field, and hence theposition of the magnetic north and south poles.

Front 16

Inclined Circular Orbit

Back 16

Anorbit whose inclinationin reference to theequatorial plane is notzero and has aneccentricity of near-zero.

Front 17

Coarse/Acquisition Code

Back 17

Each GPS satellite transmits a uniquepseudorandom code every millisecond. The GPS receiver has acopy of all the satellite codes and compares the signal todetermine which satellite is sending the code and ‘shifts’ the signalto determine the apparent range to a satellite.

Front 18

Ephemeris Data

Back 18

GPS satellites transmit information about their location (current and predicted), timing and "health" via what is known as ______________. This data is used by the GPS receivers to estimate location relative to the satellites and thus position on earth.

Front 19

Trilateration

Back 19

The process of determiningabsolute or relative locations of points bymeasurement of distances, using thegeometry of circles, spheres or triangles.

Front 20

Selective Availability

Back 20

An intentional degradation of public GPS signals implemented for national security reasons.

Front 21

Multipath Distortion

Back 21

Caused by radio signals bouncing of buildings, and/orcertain ground types. These signals are delayed and so cause inaccuracies.

Front 22

Dilution of Precision

Back 22

Configuration of satellites.

Front 23

DGPS

Back 23

Uses a network of fixed,ground-based referencestations to broadcast thedifference between thepositions indicated by thesatellite systems and theknown fixed positions.

Front 24

Circular Error Probability

Back 24

The radius of a circle inwhich 50% of the values occur.

Front 25

Distance Root Mean Squared

Back 25

A single numberthat expresses 2D accuracy. Equal to the square root of the standard error of x coordinatesquared plus the standard error of y coordinate squared.

Front 26

Wide Area Augmentation System

Back 26

A network of ground-based reference stations, in North America and Hawaii, to measure small variations in the GPS satellites' signals in the western hemisphere. Measurements from thereference stations are routed to master stations,which queue the received Deviation Correction(DC) and send the correction messages togeostationary WAAS satellites.