History of GPS (Global Positioning System) ~

Wednesday, September 14, 2011

NAVSTAR GPS or GPS is an acronym often abbreviated of Navigation System with Time and ranging Global Positioning System. GPS is a navigation system and satellite-based positioning can be used by many people at once in all weather, and is designed to provide position and velocity three-dimensional rigorous and time information, continuously throughout world.

GPS is an artificial satellite of the United States initially used for military interests, but on its development until This satellite is currently also used for the public interest. 

The background of the development of satellites (GPS) because:

1. Satellite is relatively short age

2. The number of small satellites

3. The number of orbits that fewer and more difficult

4. Using one of the reference datum (WGS '84)

5. Military field applications, digital maps, civil, etc.

Currently the GPS satellites that operate at least amount to 24 satellites, which orbit each satelinya has 6 orbits of a flat trajectory - average have a lifetime maximum of 7.5 years. 

GPS Systems

• Hardware: Satellite, Receiver
• Software: Software saatpeluncuran, while processing software, the software calculates accuracy, data processing software,
• Brainware: Formula math and logic-mathematical logic.
•  Application

Pertubasi: disruption of satellites that orbit the satellite trajectory is not the same as the modeling of the satellite orbit is ellipse. Disturbance can be either gravity, gravity months, and others. Formula pertubasi usually formulated in Deferensial Order 2:

Coordinates on the GPS system

1.reviewed from Satellite:

• Sky Coordinate System

Origin: coincides with the center of mass of the Earth (geosentrik)

Positive Z axis: toward the north pole sky (KUL)

Positive X-axis: the direction of the Vernal Equinox

Positive Y-axis: perpendicular to the axis X and Z, so that the full form right-handed system

Kordinal sky system parameters:

1. Asensio rekta (α)

2. Declination (δ)

3. The distance of celestial bodies to the earth's center (r)

Sky Coordinates image system:

Caption:

α = Asensio rekta

δ = declination

r = distance

P = Pole northern sky (KUL)

M = Earth

VE = Vernal Equinox (the point of intersection between the equator of the heavens with the ecliptic

S = sky objects (stars, sun, moon, etc.)

• Coordinate System Orbit
• 3D Coordinate System Kartesi

2.reviewed from the Observer:

1. Terrestrial Coordinates System

Terrestrial Coordinates System (SKT)

Origin: coincides with the center of mass of the Earth (geosentrik)

• Z axis positive: through the north pole CTP (Conventional Terrestrial Pole) who was adopted from the CIO that is the north pole of the earth averages 1990-1905
• Positive X-axis: the Greenwich meridian
• Positive Y-axis: perpendicular to the axis X and Z, so that the full form right-handed coordinate system

SKT Parameters:

• geodetic latitude
• geodetic longitude
• Height above the reference ellipsoid
• Origin (geosentrik)

To make the geodetic latitude should have the following requirements:

• Field of reference ellipsoid (have half the long axis and half short axis)
• The existence of the coordinate system
• Prime Vertical: Normal allipsoid (line perpendicular to the ellipsoid)geodetic longitude Prime Vertical: Large angle formed from field to field meridian meridian O.

        observer.Geodetic latitude: angle difference between the fields of the equator with the prime meridian vertical to the field observer.

Image Coordinate System Terrestrial:

Caption:

N = radius of curvature of the main vertical

λ = geodetic longitude

φ = geodetic latitude

h = height of the reference ellipsoid

O = origin (center of mass of the earth)

S = monitoring stations

CTP = Conventional Terrestrial Pole

P = the north pole of the earth for a moment

Xs, Ys, Zs = coordinates of monitoring stations kartesi

         2. Toposentris Coordinate System

            Coordinates System coordinates kartesi Toposentrik is sisitem 3D berorigin at the point of the observer (on earth) with reference to the ellipsoid normal line direction of strand or strands dititik origin.

Coordinates System Parameters Toposentrik:

* Azimuth

* elevation

* Origin (located on the surface of the earth)

Azimuth: The angle formed between the north with the geodetic reference point.

Elevation: The angle formed from horizonpengamat to the target object in the form of vertical angle

Origin: on the earth's surface titikpengamat

Positive W axis: coincides with the normal ellipsoid, positive towards the zenith

Positive U-axis: positive toward the north geographic

Positive V-axis: positive eastward, complete right-handed system.

image Caption:

Caption:λA: geodetic longitude of point A

φA: geodetic latitude of point A

O: origin the center of the earth

HA: high against the reference ellipsoid

A: The origin on the surface of the earth

        3. Map Coordinate Systems

         4. 3D Coordinate System Kartesi

Systems and Sub Systems GPS

Divided into 3 parts:

1. USER

USER or user is utilizing all the parties GPS satellites to needs.

2. CONTROL: of the five station locations

remain on earth, can be monitored satellite health that includes speed satellites,trajectory of its orbit

Sub has the main task of this system include: Satellite monitoring and control system continuously, the determination GPS system time, satellite predict efemeris, and behavior recording devices time on the satellite and periodically update the navigation message for each satellite.

3. ORBIT (published later........)

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> Datum

Origin: depending on the ellipsoid is used, if WGS 1984 originnya at the center of mass of the earth

Positive Z-axis: the direction of Earth's north pole

Positive X-axis: the direction

Positive Y-axis: perpendicular to the axis X and Z, so that the full form right-handed coordinate system.

a  = half the long axis of the ellipse

b  = half the short axis of the ellipse

f   = thinning

O = origin