gps navigation

By- Sujay Charania(07EC002)Keval Thakker(07EC043)

Guided by- Assi. Prof. Hardik BhattHead of EC Dept.

GPS Based Device for Navigation

1Gandhinagar Institute of Technology - ECE 2011

Why this project?

• Understand GPS hardware, Interface microcontroller circuit & associated software.

• Keen interest in the field of Satellite Network technology.

• Handy technology which can be used for human welfare.

• Implement the Satellite network technology for common use.

Gandhinagar Institute of Technology - ECE 2011 2

Contents:• Definition• GPS Basics• Trilateration• Block diagram• Circuit diagram• Working• GPS – Made better• Real time applications• Future scopes


Definition:

• The device is the circuit that uses the Global Positioning System to determine the precise location of itself.

• It can determine the location of a vehicle (trains, trucks, cars etc.) to which it is attached and deliver the exact position of the same at regular predefined time intervals.


GPS Basics• Global Positioning System

(GPS) is a satellite based navigation and position determination service.

• The U.S. military developed and implemented this satellite network as a military navigation system, but later made the network available for general public.

• It is a constellation of 27 Earth-orbiting Satellites (24 in operation and three spare in case one fails).

Photo courtesy U.S. Department of Defense

The GPS satellite constellation


http://en.wikipedia.org/wiki/File:ConstellationGPS.gif

(cntd…) GPS Basics• Each of these solar powered satellites(MEO

satellites) encircles the globe at about 12,000 miles (19,300 km), making two complete rotations every day.

• The satellites of GPS system utilises 6 orbits separated by 60° with 4 satellites in each orbit. The inclination of each orbit is 55°.

• The orbits are arranged such that, at any time anywhere on Earth, there are at least four satellites "visible" in the sky.


• Each satellite transmits its own positional information in L band (1 – 2 GHz).

• A GPS receiver's job is to locate four or more of these satellites, figure out the distance to each, and use received information to determine its own location.

• This facility is provided free of cost. That means once the receiver is purchased, the technology is free to use.

• The operation of determining / calculating of its own position is based on a simple mathematical principle called trilateration.

(cntd…) GPS Basics


Step 1 :Triangulation from satellites is the basis of the GPS system.

Step 2 :To triangulate, GPS measures distance using the travel time ofa radio message.

Step 3 :To measure travel time, GPS needs very accurate clocks.

Step 4 :Once one know distance to a satellite, then he/she needs to know where the satellite is in the space.

Step 5 : As the GPS signal travels through the Earth’s atmosphere, it gets delayed.

How GPS works?


Measurements of distance: how it works

• Distance measurement

end: 0.06 s

12,000 mi

start: 0.00 s


Geometric Principle: You can find one location if you know its distance

from other, already-known locations.

2-D Trilateration


30 Km

GIT can be anywhere on the - - circlecentered at Ahmedabad.

Ahmedabad

2-D Trilateration


30 Km

15 Km

Ahmedabad

Kalol

GIT can be either at one of two intersection points.

2-D Trilateration


30 Km

15 Km

Ahmedabad

Kalol

1 Km

Khatraj

Confirmed location of GIT at intersection of 3 circles.

Trilateration

• Given 1 satellite …


…Trilateration

• We can locate our position on the surface of a sphere

14Gandhinagar Institute of Technology- ECE

2011

…Trilateration

• Given 2 satellites …

15Gandhinagar Institute of Technology - ECE

2011

…Trilateration



2011

…Trilateration

• We can locate our position on the intersection of 2 spheres (i.e. a circle)


2011

…Trilateration



2011

…Trilateration

• We can locate our position on the intersection of 3 spheres (i.e. 2 points)


2011

…Trilateration

• Given 4 satellites we can locate our position on the intersection of 4 spheres (i.e. 1 point)


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…Trilateration

• The point should be located on the earth’s surface


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…Trilateration

• The precise location is determined.• Giving variables like Longitude, Altitude, Height and

Time, etc.


2011

3-D Trilateration1 Satellite 2 Satellites

3 Satellites


24

How much ACCURACY we can get ???

100 meters : ???

15 meters : ???

5 meters : ???

3 meters : ???

This is not as simple as it looks !!! The question arises here is :

“How much the measurement accuracy ??? “

Is it ?

Gandhinagar Institute of Technology - ECE 2011

Block Diagram:

Micro-Controller

unit

GPS Module

Regulated Power Supply

LCD Display

Memory

Keypad


GPS MODULE:

TOP VIEW BOTTOM VIEW


Circuit Diagram:


Working:

• The GPS equipment can be for on-line tracking or off-line tracking.

• It can be of “Logger” or “Pusher” or ”Puller” type.

• Suitable operating mode of GPS will be selected.

• The GPS module receives the information


Continued..• Passes it to the controller unit at regular

intervals.

• The controller extracts the required information and makes a packet out of it that consists of geographical data and other information.

• This data, being in coded form, is converted in the human understandable form.


Continued..• The coded form is nothing but the latitude,

longitude, azimuth, elevation, Tilt, etc., wise location description of the vehicle being tracked, as per the selected mode.

• The controller will decode the information available from GPS module.

• At the end user gets the information by interfacing the GPS device to the PC or can display it on the LCD connected along with.


FRAMES FROM SATELLITESIn GGA mode the data packet received is as

follows(format ,example):

$GPGGA,hhmmss.sss,ddmm,mmmm,a,dddmm.mmmm,a,x,xx,x.x,M,x.x,M,x.x,xxxx*hh <CR><LF>

• $GPGGA,035238.000,2307.1219,N,12016.4423,E,1,9,0.89,23.6,M,17.8,M,,*69

• By extracting UTC , Longitude, and latitude one can have the exact position of himself.


GPS - MADE BETTER:• Differential GPS is a technique that allows

overcoming the effects of environmental errors and SA in the GPS signals to produce highly accurate position fix.

• This consists of a number of ground reference stations that monitor GPS satellite data.

• Master stations collect data from reference stations and creates a GPS correction message.


Continued..• The corrected differential message is then

broadcast through one of the two geostationary satellites


Continued..• Development of satellite-based differential

systems by various governments.

• These systems can give a position accuracy 5 times better, 95% of the time.

• Countries using such technologies: WAAS U.S.A. EGNOS Europe MTSAT Japan GAGAN India


POSSIBLE UPGRADATIONS:

• This on-line tracker can be upgraded to a real time off-line “Logger” type equipment by adding some external memory unit.

• It can also be transformed into a partial off-line “Puller” type or an advanced on-line “Pusher” type device by allow it to communicate with the controller.


APPLICATION OF GPS• Science and research • Commerce and industry • Agriculture and forestry •Tourism/sport Military • Time measurement • Tracking of any object • Survey of land • Communications Technology


Real Time Application:

Currently used in :•Navigation series mobile phones/accessories•“MANAN CABs in Ahmedabad.”•Study the locomotion of some animal/bird.•Universal clock.


Future scopes:•Major domestic bus travelling companies.•108 Ambulance (Emergency services)•High way security Projects.•Personal following.•Pet tracking. •Many more…


That’s all

THANK YOU.!!

QURIES.??(If Any)


gps navigation

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