GLOBAL POSITIONING SYSTEMS

INTRODUCTION

• The feasibility studies on GPS is begun in 1960’s bythe Defense Navigation Satellite System (DNSS), andfirst satellite launched in 1978, while the systemdeclared fully operational in April, 1995. The system is made up from 26 satellites (24

functioning & 2 spares). Each satellite is 20,000 kmhigh (from earth’s surface) in a fixed position. Orbits are planned so that at least 4 satellites are

always in view. The location of the objects on earth isdetected by distance-distance intersection.

Now a days GPS become more popular as we find itsway into car, boats, planes, construction equipments,farm machinery, laptop and computer etc…, so now itsbecome almost as basic as telephone. The global positioning system is comprised of three

segments: Space segment Operational control segment User equipment segment

User segment GPS antennas & receiver/processors Position Velocity Precise timing Used by Aircraft Ground vehicles Ships Individuals

POSITIONING USING SATELLITE SIGNALS

A position is based on real-time satellite tracking andit’s defined by a set of coordinates.

A position represents only an approximation of thereceiver’s true location.

A position is not static. It changes constantly as theGPS receiver moves (or wanders due to randomerrors).

A receiver must be in 2D or 3D mode (at least 3 or 4satellites acquired) in order to provide a position fix.

3D mode dramatically improves position accuracy.

Application of GPS Technology

Location - determining a basic position Navigation - getting from one location to another Tracking - monitoring the movement of people and

things Mapping - creating maps of the world Timing - bringing precise timing to the world

Private and recreation Traveling by car Hiking, climbing, biking Vehicle control

Mapping, survey, geologyAgriculture General and commercial Spacecraft

Maritime

REMOTE SENSING

INTRODUCTION Remote means far away and sensing means acquiring

some information. So, remote sensing meansacquiring information of objects from a very largedistance. In the remote sensing, whole the data of the earth

surface are captured and then used for generating amap. Remote sensing is the science and art of obtaining

information about an object, area or phenomenonthrough an analysis of the data acquired by a devicewhich is not in contact with the object underinvestigation.

So, it consists collecting and interpreting informationabout an object without being in physical contact withthem. The remote sensing use electromagnetic energy as

means of detecting and measuring targetcharacteristics. The data collection of the remote sensing is carried

out by highly sophisticated sensors like camera,multispectral scanner, radar etc… and the databasically consists of wave length intensityinformation. The sensors are located at so high that they can make

images of a very large area, and now a days remotesensing is mainly done from space using satellites.

CLASSIFICATION OF REMOTE SENSING

Remote sensing is broadly classified into twocategories:a) Passive remote sensingb) Active remote sensing

a) Passive remote sensing It uses sun as a sources of EM energy and records

the energy that is naturally radiated and /orreflected from the objects, and the photographs aretaken on a clear bright days.

b) Active remote sensing It uses its own source of EM energy, which is

directed towards the object and return energy ismeasured. So, this system utilizes man-madesources of energy for data collection.

APPLICATION OF REMOTE SENSING

Remote sensing has a very broad application whichproves very useful for accurate and continuousmonitoring of the earth’s natural and other resourcesand of determining the impact of man’s activities onair, water and land. Remote sensing data can be used for taking sound

decisions for planning many human developmentactivities. It is also possible to take preventive action as in the

case of forest fires and natural disasters.

Some of the major application of remote sensing areas under: Agriculture Forestry Environment Coastal mapping Marine application Urban environment Land and water resources development Geology Land use/ land cover Information

GEOGRAPHIC INFORMATION SYSTEM

INTRODUCTION

The Geographical Information System (GIS) consistsof two distinct disciplines, geography and informationsystem. It is the data management system thatprovides many facilities for surveyors and planners. GIS is a computer based system which collects and

stores spatially referenced data with other relevantattributes and enables us to manipulate, analysis anddisplay in suitable formats. GPS and RS are sources of input data for a GIS. A GIS

provides for storing and manipulating GPS and RSdata.

Objectives of the GIS

The basic objectives of the GIS are as follows:a) To collect, analyses and manipulate spatial data.b) To produce maps and other products in

standardized formats for different uses.c) To supply information in useful formats for logical

decision making for planners.d) To support research activities using spatial as well

as non spatial data.

DEFINATION

The GIS has been defined in many ways:

GIS may be defined as a computer based informationsystem which attempts to capture, store, manipulate,analyze and display spatially referenced andassociated attribute data for solving complexresearch, planning and management problems. GIS is a systematic integration of computer hardware,

software and spatial data for capturing, storing,displaying, updating, manipulating and analyzing inorder to solve complex management problems.

GIS is defined as an information system that is usedto input, store, retrieve, manipulate, analyze andoutput geospatial data or geographically referenceddata, in order to support decision making forplanning and management of land use, naturalresources, transportation, urban facilities,environment and other administrative records.

Key components of GIS

The GIS consists of five key components as under:

Hardware Software Procedure Data Users

Function of GIS

What would happen if . . .A chemical leaked into a river?

Where does . . .The Green Belt exist in relation to the City?

Has . . .Population changed over the last ten years?

Is there a spatial pattern related to . . .Car ownership in our area?

GIS APPLICATIONS

Surveying and mapping are the primary area of GISapplication. The following are the major applicationof GIS: Engineering mapping Automated photogrammetry Highway mapping Utility/facility mapping/management Land use management Natural resources management Routing – highway, pipeline.. Urban and regional planning