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ABSTRACT
GPS tracking systems are used in a variety of applications from civilian to
military. Our design focuses on civilian applications, specifically vehicle
tracking systems. The motivation for our GPS tracking system is to internet-
enable the GPS device, while simplifying its operation and user interface.
Our connection to the Internet will be established via the GPRS protocol,
which provides good coverage and sufficient data transmission speeds. Our
prototype system will comprise of a Sony-Ericsson Cell Phone (GPRS
Device), a GARMIN eTrex GPS device, and a PIC Microcontroller,
The basic concept of this system is to be able to track a vehicle over the
Internet; this is accomplished using software and hardware that was designed
for this reason alone. The software component of this design project is fairly
substantial while all the hardware was built out of necessity to make the end
product portable.
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CONTRIBUTIONS
The philosophy that guided our design team was to work together as much as
possible. We were fortunate that the all group members were able to get
along well enough to have group meetings at the rather demanding frequency
this project called for. This project from beginning to end has been conceived,
designed and implemented as a team. Due the unique manner in which this
project was accomplished it is almost impossible to assign accurate credit to
any individual group members
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ACKNOWLEDGEMENTS
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LIST OF ABBREVIATION...................................................................................................................7
CHAPTER NO. 1.................................................................................................................................8
1.1 - INTRODUCTION............................................................................................................................9
1.1.1 - PURPOSE.................................................................................................................................91.1.2 - PROBLEM.................................................................................................................................91.1.3 - SCOPE...................................................................................................................................10
1.2 – PROJECT DIAGRAM..................................................................................................................11
1.3. PROJECT OVERVIEW..................................................................................................................12
1.3.1. GPS DEVICE (GPS RECEIVER)......................................................................................121.3.2. MICROCONTROLLER........................................................................................................131.3.3. GPRS ENABLED DEVICE (CELL PHONE)......................................................................131.3.4. WEB SERVER...................................................................................................................14
CHAPTER NO. 2...............................................................................................................................15
GLOBAL POSITIONING SYSTEM.............................................................................................................16
2.1 - INTRODUCTION.......................................................................................................................16
2.1.1. HOW IT WORKS..............................................................................................................162.1.2. SOME LIMITATIONS..........................................................................................................172.1.3. THE GPS SATELLITE SYSTEM........................................................................................17
2.2 - APPLICATIONS OF GPS SYSTEMS.........................................................................................18
2.2.1 - TRACKING DEVICES.................................................................................................................182.2.2 - NAVIGATION SYSTEMS.............................................................................................................19
2.3 - GPS TRACKING AND ITS APPLICATIONS..............................................................................20
2.3.1 - GPS TRACKING........................................................................................................................202.3.2 - GPS VEHICLE TRACKING.........................................................................................................212.3.3 - COORDINATED TRACKING........................................................................................................212.3.4 - CONSUMER GPS TRACKING [6].................................................................................................22
2.4 - TECHNICAL DESCRIPTION.....................................................................................................23
2.4.1 GPS SYSTEM SEGMENTS...............................................................................................232.4.1.1. Space Segment.............................................................................................................232.4.1.2. Control Segment..........................................................................................................242.4.1.3. User Segment..............................................................................................................24
2.4.2 NAVIGATION SIGNALS.....................................................................................................252.4.3 CALCULATING POSITIONS...............................................................................................262.4.4 ACCURACY AND ERROR SOURCES................................................................................27
2.4.4.1. Atmospheric Effects...........................................................................................................282.4.4.2. Multipath Effects.................................................................................................................292.4.4.3. Ephemeris and Clock Errors.............................................................................................302.4.4.4. Selective Availability..........................................................................................................302.4.4.5. GPS Jamming.....................................................................................................................312.4.4.6. Relativity..............................................................................................................................32
2.4.5 GPS TIME AND DATE.....................................................................................................332.4.6 GPS TIME TRANSFER.....................................................................................................33
2.5 DIFFERENTIAL GPS..................................................................................................................35
2.5.1. REAL-TIME DGPS...........................................................................................................352.5.2. SATELLITE DIFFERENTIAL SERVICES..............................................................................362.5.3. REPROCESSING REAL-TIME DATA..................................................................................372.5.4. POSTPROCESSING CORRECTION.....................................................................................37
2.5.4.1. Public Sources.............................................................................................................382.5.4.2. Commercial Sources...................................................................................................38
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2.5.4.3. Web-Based Services....................................................................................................382.5.4.4. Base Station Ownership..............................................................................................38
2.5.5. SUMMARY.........................................................................................................................39
2.6 CONTENTS RECEIVED FROM GPS RECEIVER.........................................................................40
CHAPTER NO.3................................................................................................................................42
3.1 MICROCONTROLLER...............................................................................................................43
3.1.1. WHAT IS A MICROCONTROLLER?..................................................................................433.1.2. PIC16F877....................................................................................................................44
3.2 USE OF MICROCONTROLLER IN VTS................................................................................44
3.2.1 GPS INTERFACING WITH MICROCONTROLLER..............................................................443.2.2 DATA FLOW.....................................................................................................................47
3.3 SCHEMATIC DIAGRAM..........................................................................................................48
3.4 ARCHITECTURE OF PIC16F87X FAMILY.........................................................................48
3.5 ARCHITECTURAL DIAGRAM OF PIC16F87X FAMILY [38]........................................50
3.6 PIN DIAGRAM OF PIC16F87X [38]....................................................................................51
3.6.1. PORT A FUNCTIONS.............................................................................................................513.6.2. PORT B FUNCTIONS.............................................................................................................523.6.3. PORT C FUNCTION...............................................................................................................523.6.4. PORT D FUNCTION...............................................................................................................533.6.5. PORT E FUNCTION...............................................................................................................53
3.7 CONTROLLER SPECIFICATIONS [38]....................................................................................54
CHAPTER NO.4................................................................................................................................55
GPRS MOBILE...................................................................................................................................55
4.1 - GPRS..........................................................................................................................................56
4.1.1. GPRS FEATURES..............................................................................................................574.1.1.1. Speed...................................................................................................................574.1.1.2. Immediacy..........................................................................................................574.1.1.3. New Applications, better Applications.....................................................584.1.1.4. Service Access..................................................................................................58
4.1.2. KEY NETWORK FEATURES OF GPRS............................................................................594.1.3. LIMITATIONS OF GPRS....................................................................................................614.1.4. APPLICATIONS FOR GPRS...............................................................................................634.1.5. OPTIMAL BEARER BY APPLICATION...............................................................................704.1.6. GPRS NETWORK NODES...............................................................................................72
4.2 - GPRS DEVICE............................................................................................................................73
4.2.1. WHAT IS A GPRS MODEM?...........................................................................................734.2.2. PUBLIC INTERNET ACCESS TO GPRS DEVICES...........................................................734.2.3. PRIVATE NETWORK ACCESS TO GPRS DEVICES.........................................................744.2.4. GPRS MOBILE DEVICE...................................................................................................744.2.5. GPRS CLASSES OF GPRS DEVICE..............................................................................74
4.3 - AT COMMANDS.........................................................................................................................75
CHAPTER NO.5................................................................................................................................81
MAP DIGITIZATION.......................................................................................................................81
5.1 - INTRODUCTION..........................................................................................................................82
5.1.2 - GPS MAPS............................................................................................................................845.1.3 - DIGITIZATION OF MAPS.......................................................................................................855.1.4 - MAP PROJECTIONS................................................................................................................88
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5.1.5 - DISTORTIONS........................................................................................................................885.1.6 - MAP SCALE...........................................................................................................................895.1.7 - PROBLEMS IN THE DIGITIZATION OF MAPS.........................................................................905.1.8 CONCLUSION: THE FUTURE OF MAP REPRODUCTION.........................................................90
5.2 - MAP DIGITIZATION PROCESS................................................................................................92
5.2.1 - PROCESS TO DIGITIZE THE MAP........................................................................................93
CHAPTER NO.6..............................................................................................................................101
VEHICAL TRACKING WEBSITE DEVELOPMET.....................................................................101
6.1 DEFINITION............................................................................................................................102
6.2 OVERVIEW.............................................................................................................................102
6.3 INTRODUCTION.....................................................................................................................103
6.4 WEBSITE ARCHITECTURE...................................................................................................103
6.5 WEBSITE MODULES............................................................................................................104
6.6 MAPPING THE LATITUDE & LONGITUDE........................................................................104
6.7 STRING SEPARATION (GPSSTR.ASPX)...........................................................................105
6.8 MAP (MAP.ASPX)............................................................................................................108
6.9 IMAGE RENDER (IMAGERENDER.ASPX).................................................................108
6.10 FUNCTIONS.......................................................................................................................109
6.10.1. ADMINISTRATIVE FUNCTIONS...................................................................................1106.10.1.1. Add Client.........................................................................................................1116.10.1.2. Change Password..........................................................................................1126.10.1.3. Edit Client.........................................................................................................1126.10.1.4. Change Profile Information........................................................................1136.10.1.5. Search Client...................................................................................................1136.10.1.6. Ownership Transfer.......................................................................................1146.10.1.7. Track Client......................................................................................................115
6.10.2. CLIENT FUNCTIONS..................................................................................................1166.10.2.1. Real Time Tracking.......................................................................................1176.10.2.2. View Profile......................................................................................................1176.10.2.3. Change Password..........................................................................................1186.10.2.4. Edit Profile........................................................................................................1186.10.2.5. Static Tracking................................................................................................1196.10.2.6. Tracking by History.......................................................................................119
REFRENCES.......................................................................................................................................121
Glossary..............................................................................................................................................122
List of Abbreviation
TermDescription
Email Electronic Mail
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TermDescription
GPS Global Positioning SystemWWW World Wide WebWAP Wireless Application ProtocolGPRS General Packet Radio ServiceXML Extensible Markup LanguageASP Active Server Pages.NET Microsoft .Net PlatformADO Activex Data Objects
NAVSTAR Navigation Satellite Timing And Ranging Global Positioning System
NGA National Geospatial-Intelligence AgencySOPS Space Operations SquadronUSAF United States Air ForceNMEA National Marine Electronics AssociationSoL Safety-Of-LifeWGS World Geodetic SystemPRN Pseudo-Random NumberSA Selective AvailabilityRAIM Receiver Autonomous Integrity MonitoringMCU MicrocontrollerRAM Random Access MemoryROM Read Only MemoryEPROM Erasable Programmable Read-Only MemoryEEPROM Electrically Erasable Programmable Read-Only MemoryA/D CONVERTOR Analog To Digital ConverterPWM Pulse Width ModulationLED Light Emitting DiodeVTS Vehicle Tracking System
USART Universal Synchronous Asynchronous Receiver Transmitter
IC Integrated CircuitPC Personnel ComputerCOM PORTS Communication PortsMAX232 A Type Of ICMAXIM Company Who Made Max232TTL Time To LiveBPS Bits Per SecondI/O Input OutputTX Transmitting ModuleRX Receiving ModuleRISC Reduced Instruction Set ComputerDC Direct CurrentMHz Mega HertzmA Mega AmpereµA Micro AmpereV Volts
Chapter No. 1
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INTRODUCTION
(Proposal, Diagram and Technologies Used In order)
1.1 - INTRODUCTION
1.1.1 - Purpose The main purpose of this whole project was to create a web GPS enable
vehicle tracking system while maintaining a very high level of usability so that
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the end user would not need to have any background knowledge of GPS
systems at all. The only thing the end user would have to worry about is
being able to have access to the Internet. We have assumed that this is not
a problem because almost everyone has an Internet enabled computer these
days. Once online, the user would only have to enter a specified username
and password to gain access to the GPS data.
1.1.2 - Problem
The concept of tracking a vehicle is by no means something that is new in the
world of GPS tracking systems. This design project brings a new twist to this
application by web enabling the entire system. After a brief research stint into
the world of vehicle tracking, it was found that there aren’t any available
systems in the market place that actually provide online GPS tracking that can
be done by a single user without the assistance of a third party company.
Due to the fact that with the installation of this system, the user is capable of
tracking his/her vehicle over the Internet might be a deterrent to possible car
thieves. This system could also be used to help track down vehicles that have
been stolen and thus increase the possibility of vehicle recovery.
Currently, car rental companies do track their vehicles, but this service is
being provided by a third party, with the installation of this system into their
vehicles, these rental car companies could track their vehicles on their own.
This would definitely reduce their overhead cost and this in turn would reduce
the prices that they charge for car rentals.
On a lighter note, this device when installed in a vehicle could be used to
track family members. One of the many future implementations of this system
would be to reduce its size considerably and then it can be placed in cell
phones and other devices so that individual human beings could be tracked.
1.1.3 - Scope
This project was divided up into two basic categories which consisted of
hardware and software components. The hardware component was limited to
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mainly building the necessary RS-232 and power circuits that were used to
integrate with the microcontroller. The main components that were used for
this project was a GPS device, a GPRS device and a microcontroller.
Software design was the main concern of this design project. The entire
software set was programmed using Vb.net/ Asp.net, which is one of the most
famous and powerful computer languages today.
C was chosen because it was the programming language that was needed to
program the microcontroller that was selected for this project. All the software
was designed to be completely modular thus making it easier to do verification
and testing.
1.2 – PROJECT DIAGRAM
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1.3. PROJECT OVERVIEW
(Summery with Technologies)
We are using different types of devices and services in our project which are
explained as under
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i. GPS Device (GPS Receiver)ii. Microcontroller iii. GPRS Enabled Device (Cell Phone)iv. Web Server
Also there are two types of users that will use this system according to there
rights.
These are
Administrator User
1.3.1. GPS Device (GPS Receiver)
As we know that the GPS is known as the Global Positioning System, this
system is basically used to track and locate the humans, Vehicles, ships,
Planes Submarines etc.
So to track and locate anything we have to use a device through which
anything can be located.
GPS devices are of many kinds and the basic functionality is to provide the
coordinates about your position and these coordinates are of the form of
Longitude and Latitude. Other functionalities include a compass that provides
you the direction that in which direction you are moving whether it is South,
East etc. It also provides us the speed of the vehicle if we are moving in a
vehicle. We can also make a track using the option of waypoints, for this we
have to mark the waypoints at different positions of the way through where we
are going so when we complete our journey then at the end of the journey
there is track showing us the way through which we have come and following
these way points we can reach where we get started.
So in our project we use the two coordinates which are Longitude and
Latitude, these coordinates are send to the Microcontroller and then the
Microcontroller do the necessary processing on to the received data
1.3.2. Microcontroller
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Broadly speaking a Microcontroller is a single chip microprocessor which
contains data and program memory, serial and parallel port I/O lines (Pins),
timers, external and internal interrupts, all integrated into a single chip that
can be purchased for a very low price.
We will use the Microcontroller to get the data from the GPS device and send
that data to the GPRS enabled device.
The Microcontroller sends and receives the data with the help of “TX” and
“RX” Modules.
The TX Module is used to transmit the data to the GPRS enabled device
which is transmitted with the help of AT commands i.e. used to handle the
mobile device. We can do any function which we are doing on our mobile
phone; normally for this we will use serial communication where the data is
stored on to a buffer before it is sent to the GPRS enabled mobile.
With respect to RX module it is used to receive the data from the GPS device.
The GPS device automatically sends the data through the serial port after
regular intervals and the Microcontroller get that data using the RX Module. In
order to get data continuously, we will get the data from the buffer; leave it
empty in order to get the data again for the transmittion.
1.3.3. GPRS Enabled Device (Cell Phone)
Basically we are using the modem of the cell phone with the help of the AT
command set because we have to communicate with the GRPS
Device(mobile) using some sorts of commands which are standard AT
commands.
Also we are using service of the GPRS which is provided by the service
provider, we are using the services of the TELENOR.
So with the help of AT commands we send our data to a web server where
the data is stored and then we used this data to point out the location on a
digital map.
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We are using GPRS because it provide us high speed data rates at low price
rather than the if we use sms as it is costly and it also did not give us the real
time data transfer.
1.3.4. Web Server
Web server is used to host our site which contains the User modules and the
Administrator module and for this we need a static IP which is used in order to
interact our site, it also include a digital map.
So the Microcontroller gets the data from the GPS receiver and send data
with the help of AT commands through the mobile phone towards our website
where the data is stored in database, that data consists of Longitude,
Latitude, time and date, and then coordinates from the database are plotted
on the map.
As our web server has two modules so in Administrator module we basically
handle the data base and the users. In user module user can only see the
location where it is and where it was, it did not have access to the user
management module and to the data base.
Vehicle Unit
Chapter No. 2
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Global Positioning System
GLOBAL POSITIONING SYSTEM
2.1 - INTRODUCTION
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The GPS is currently the only fully-functional satellite navigation system. More
than 24 GPS satellites are in medium Earth orbit, transmitting signals allowing
GPS receivers to determine the receiver's location, speed and direction.
Since the first experimental satellite was launched in 1978, GPS has become
one of the important devices for navigation around the world and an important
tool for map-making and land surveying. GPS also provides a precise time
reference used in many applications including scientific study of earthquakes,
and synchronization of telecommunications networks.[1]
Developed by the United States Department of Defense, it is officially named
NAVSTAR GPS. The satellite constellation is managed by the United States
Air Force 50th Space Wing. Although the cost of maintaining the system is
approximately US$400 million per year, including the replacement of aging
satellites, GPS is free for civilian use as a public good. GPS works in any
weather conditions, anywhere in the world, 24 hours a day. There are no
subscription fees or setup charges to use GPS. [1]
2.1.1. How It Works
GPS satellites revolve around the earth twice a day in a very precise orbit and
transmit signal information to earth. GPS receivers take this information and
use triangulation to calculate the user's exact location. Essentially, the GPS
receiver compares the time a signal was transmitted by a satellite with the
time it was received. The time difference tells the GPS receiver how far away
the satellite is. Now, with distance measurements from a few more satellites,
the receiver can determine the user's position and display it on the unit's
electronic map.[2]
A GPS receiver must be locked on to the signal of at least three satellites to
calculate a 2D position (latitude and longitude) and track movement. With four
or more satellites in view, the receiver can determine the user's 3D position
(latitude, longitude and altitude). Once the user's position has been
determined, the GPS unit can calculate other information, such as speed,
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bearing, track, trip distance, distance to destination, sunrise and sunset time
and more. [2]
2.1.2. Some Limitations
GPS can provide worldwide, three-dimensional positions, 24 hours a day, in
any type of weather. However, the system does have some limitations. There
must be no obstruction between the GPS antenna and four or more satellites.
Objects, such as buildings, overpasses, and other obstructions, that shield the
antenna from a satellite can potentially weaken a satellite's signal such that it
becomes too difficult to ensure reliable positioning. These difficulties mostly
prevail in urban areas. The GPS signal may bounce off nearby objects
causing another problem called multipath interference.
2.1.3. The GPS Satellite System
The 24 satellites that make up the GPS space segment are orbiting the earth
about 12,000 miles above us. They are constantly moving, making two
complete orbits in less than 24 hours. These satellites are traveling at speeds
of roughly 7,000 miles an hour.[2]
GPS satellites are powered by solar energy. In the event of solar eclipse they
are backed by the batteries onboard. Small rocket boosters on each satellite
keep them flying in the correct path.
Here are some other interesting facts about the GPS satellites (also called
NAVSTAR2, the official U.S. Department of Defense name for GPS):
The first GPS satellite was launched in 1978.
A full constellation of 24 satellites was achieved in 1994.
Each satellite is built to last about 10 years. Replacements are
constantly being built and launched into orbit.
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A GPS satellite weighs approximately 2,000 pounds and is about 17
feet across with the solar panels extended.
Transmitter power is only 50 watts or less. [2]
2.2 - APPLICATIONS OF GPS SYSTEMS
2.2.1 - Tracking Devices
One of the easiest applications to consider is the simple GPS tracking device;
which combines the possibility to locate itself with associated communications
technologies such as radio transmission and telephony. [6]
Tracking is useful because it enables a central tracking centre to monitor the
position of several vehicles or people, in real time, without them needing to
relay that information explicitly. This can include children, criminals, police and
emergency vehicles, military applications, and many others.
The tracing devices themselves come in different flavors. They will always
contain a GPS receiver, and GPS software, along with some way of
transmitting the resulting coordinates. GPS watches, for example, tend to use
radio waves to transmit their location to a tracking center, while GPS phones
use existing mobile phone technology. [6]
The tracking centre can then use that information for co-ordination or alert
services. One application in the field is to allow anxious parents to locate their
children by calling the tracking station - mainly for their peace of mind. [6]
GPS vehicle tracking is also used to locate stolen cars, or provide services to
the driver such as locating the nearest petrol station. Police can also benefit
from using GPS tracing devices to ensure that parolees do not violate curfew,
and to locate them if they do. [6]
2.2.2 - Navigation Systems
Once we know our location, we can, of course, find out where we are on a
map, and GPS mapping and navigation is perhaps the most well-known of all
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the applications of GPS. Using the GPS coordinates, appropriate software
can perform all manner of tasks, from locating the unit, to finding a route from
A to B, or dynamically selecting the best route in real time. [6]
These systems need to work with map data, which does not form part of the
GPS system, but is one of the associated technologies that we spoke of in the
introduction to this article. The availability of high powered computers in small,
portable packages has lead to a variety of solutions which combines maps
with location information to enable the user to navigate. [6]
One of the first such applications was the car navigation system, which allows
drivers to receive navigation instructions without taking their eyes off the road,
via voice commands.
Then there are handheld GPS units, such as those from Garmin and Magellan
and a dozen other manufacturers, which are commonly used by those
involved in outdoor pursuits, and only provide limited information such as the
location, and possibly store GPS waypoints. A waypoint being a location that
is kept in memory so that the unit can retrace the same path at a later time.
More advanced versions include aviation GPS systems, which offer specific
features for those flying aircraft, and marine GPS systems which offer
information pertaining to marine channels, and tide times, etc. [6]
These last two require maps and mapping software which differ vastly from
traditional GPS solutions, and as such can often be augmented with other
packages designed to allow the user to import paper maps or charts. [6]
There are even GPS solutions for use on the golf course. Golf GPS systems
help the player to calculate the distance from the tee to the pin, or to know
exactly where they are with relation to features such as hidden bunkers, water
hazards or greens. Again, specific maps are needed for such applications.
2.3 - GPS TRACKING AND ITS APPLICATIONS
Being able to pinpoint the location of a device on planet Earth raises some
interesting ideas and applications. Primarily, GPS (Global Positioning System)
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was intended to be released to the consumer market as a way to aid
navigation. [6]
However, since the price of the GPS technology has fallen, many companies
have found new ways to apply it. Indeed, the price of associated technologies
has also fallen dramatically since the inception of GPS, which has led to many
innovations, amongst them “GPS tracking”.
2.3.1 - GPS Tracking
In fact, it is this use which represents the simplest form of GPS tracking. The
user is able, using a portable GPS device, to keep a track of where they have
been, in order to be able to either retrace their steps, or follow the same path
again in the future. [6]
When combined with other technologies such as GPS phones, this also gives
the possibility for other users of GPS to follow in the footsteps of the initial
user; which can be a useful application of GPS tracking for field activities.
Where GPS tracking comes into its own, however, is when it is combined with
other broadcast technologies such as radio. GPS watches, for example, can
be fitted with a GPS receiver which is capable of calculating its position, whilst
also broadcasting that using a miniature radio transmitter. [6]
The signal is relayed to a central command centre equipped with GPS
software systems which can track the position of the wearer, and either store
it as a path, or relay that information to a third party. [6]
That third party could be an anxious parent, or the police. In fact there are a
variety of GPS phones and wristbands which are sold in conjunction with a
service which enables third parties to find out where their charges are at any
time of the day or night. [7]
2.3.2 - GPS Vehicle Tracking
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This is particularly useful when using GPS units attached to vehicles which
have distinctive identification such as chassis numbers. The same principle
applies as for a GPS tracking device designed to be worn by a human, except
that the GPS is integrated within the vehicular electronics. [6]
This serves two purposes. On the one hand, it provides the driver with an
integrated GPS system, without the necessity to purchase a car navigation
system, or a PDA-based GPS system, whilst also offering the possibility to
relay that information via a radio or mobilephone transmitter. [6]
In fact, these systems have already been tried in the field, primarily as a
vehicle locator in the event that the vehicle to which the GPS vehicle tracking
system is attached is stolen. The police, once informed, can find out from the
control centre where the vehicle is, and proceed to track it physically. [6]
A useful consequence of being able to use GPS vehicle tracking to locate a
vehicle is that the manufacturer can also use the information to alert the driver
as to when they near a service centre.
If, along with the GPS coordinates, the system relays telemetry information
such as the status of the engine, time since the last service, or even
information not relating to defects, the receiver of this information can make a
decision as to what kind of alert to pass on to the driver.
2.3.3 - Coordinated Tracking
This also opens up the possibility to allow for coordinated vehicle tracking, in
which GPS tracking is used to share location information between several
vehicles, all pursuing the same end goal. [6]
It is an approach that has been used successfully in conjunction with GPS
fishfinder units which help fisherman to locate, track and catch schools of fish.
These units are more sophisticated than the average GPS unit, having other
features such as depth gauges, tide time information and so forth. [6]
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The basic GPS functionality is the same however, and units can either share
that information with each other, or a central point. The central point can also
be one of the fishing vessels, and it has on-board computer systems capable
of reconciling all the locator information along with a map, thus allowing the
different vessels to coordinate their actions.
This also has military applications, of course, where units can share, in real time, information about their location, even when line-of-sight is no longer possible. In the past, this was done by relaying often inaccurate map co-ordinate estimations; now the locations can be called in with high absolute accuracy.
2.3.4 - Consumer GPS Tracking [6]
Despite its’ hitech military and commercial fishing applications, as well as use
in aviation GPS, the principal application of GPS tracking will be in providing
an enabling technology to augment existing systems.
These systems will include cell phones and vehicles, usually in conjunction
with a central point of service designed to keep track of the location. The
reason for this is to keep the cost of the actual GPS unit down as much as
possible in order to supply a useful technology to consumers at an attractive
price.
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2.4 - TECHNICAL DESCRIPTION
2.4.1 GPS System Segments
The current GPS consists of three major segments. These are the space
segment (SS), a control segment (CS), and a user segment (US).
2.4.1.1. Space Segment
The space segment (SS) is composed of the orbiting GPS satellites or Space
Vehicles (SV) in GPS parlance. The GPS design includes 24 SVs to be
distributed equally among six circular orbital planes. The orbital planes are
centered on the Earth, not rotating with respect to the distant stars. The six
planes have approximately 55° inclination (tilt relative to Earth's equator) and
are separated by 60° right ascension of the ascending node (angle along the
equator from a reference point to the orbit's intersection). [1]
Orbiting at an altitude of approximately 20,200 kilometers (12,600 miles or
10,900 nautical miles; orbital radius of 26,600 km (16,500 mi or 14,400 NM)),
each SV makes two complete orbits each sidereal day, so it passes over the
same location on Earth once each day. The orbits are arranged so that at
least six satellites are always within line of sight from almost anywhere on
Earth. [1]
As of January 2007, there are 29 actively broadcasting satellites in the GPS
constellation. The additional satellites improve the precision of GPS receiver
calculations by providing redundant measurements. With the increased
number of satellites, the constellation was changed to a non uniform
arrangement. Such an arrangement was shown to improve reliability and
availability of the system, relative to a uniform system, when multiple satellites
fail. [1]
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Final Project Report Final Project Report2.4.1.2. Control Segment
The flight paths of the satellites are tracked by US Air Force monitoring
stations in Hawaii, Kwajalein, Ascension Island, Diego Garcia, and Colorado
Springs, Colorado, along with monitor stations operated by the (NGA). The
tracking information is sent to the Air Force Space Command's master control
station at Schriever Air Force Base, Colorado Springs, Colorado, which is
operated by the 2d 2 SOPS of the USAF. 2 SOPS contacts each GPS
satellite regularly with a navigational update (using the ground antennas at
Ascension Island, Diego Garcia, Kwajalein, and Colorado Springs). These
updates synchronize the atomic clocks on board the satellites to within one
microsecond and adjust the ephemeris of each satellite's internal orbital
model. The updates are created by a Kalman Filter which uses inputs from
the ground monitoring stations, space weather information, and other various
inputs. [1]
2.4.1.3. User Segment
The user's GPS receiver is the user segment (US) of the GPS system. In
general, GPS receivers are composed of an antenna, tuned to the
frequencies transmitted by the satellites, receiver-processors, and a highly-
stable clock (often a crystal oscillator). They may also include a display for
providing location and speed information to the user. A receiver is often
described by its number of channels: this signifies how many satellites it can
monitor simultaneously. Originally limited to four or five, this has progressively
increased over the years so that, as of 2006, receivers typically have between
twelve and twenty channels. [1]
GPS receivers may include an input for differential corrections, using the
RTCM SC-104 format. This is typically in the form of a RS-232 port at 4,800
bps speed. Data is actually sent at a much lower rate, which limits the
accuracy of the signal sent using RTCM. Receivers with internal DGPS
receivers can outperform those using external RTCM data. As of 2006, even
low-cost units commonly include WAAS receivers. [1]
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Many GPS receivers can relay position data to a PC or other device using the
NMEA 0183 protocol. NMEA 2000 is a newer and less widely adopted
protocol. Both are proprietary and controlled by the US-based NMEA.
References to the NMEA protocols have been compiled from public records,
allowing open source tools like GPSd to read the protocol without violating
intellectual property laws. Other proprietary protocols exist as well, such as
the SiRF protocol. Receivers can interface with other devices using methods
including a serial connection, USB or Bluetooth. [1]
2.4.2 Navigation Signals
GPS1 satellites broadcast three different types of data in the primary
navigation signal. The first is the almanac which sends coarse time
information along with status information about the satellites. The second is
the ephemeris, which contains orbital information that allows the receiver to
calculate the position of the satellite. This data is included in the 37,500 bit
Navigation Message, which takes 12.5 minutes to send at 50 bps. [1]
The satellites also broadcast two forms of clock information, the Coarse /
Acquisition code, or C/A which is freely available to the public, and the
restricted Precise code, or P-code, usually reserved for military applications.
The C/A code is a 1,023 bit long pseudo-random code broadcast at 1.023
MHz, repeating every millisecond. Each satellite sends a distinct C/A code,
which allows it to be uniquely identified. The P-code is a similar code
broadcast at 10.23 MHz, but it repeats only once a week. In normal operation,
the so-called "anti-spoofing mode", the P code is first encrypted into the Y-
code, or P(Y), which can only be decrypted by units with a valid decryption
key. Frequencies used by GPS include: [1]
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Final Project Report Final Project Report L1 (1575.42 MHz) - Mix of Navigation Message, coarse-acquisition
(C/A) code and encrypted precision P(Y) code.
L2 (1227.60 MHz) - P(Y) code, plus the new L2C code on the Block
IIR-M and newer satellites.
L3 (1381.05 MHz) - Used by the Defense Support Program to signal
detection of missile launches, nuclear detonations, and other high-
energy infrared events.
L4 (1379.913 MHz) - Being studied for additional ionospheric
correction.
L5 (1176.45 MHz) - Proposed for use as a civilian SoL8 signal (see
GPS modernization). This frequency falls into an internationally
protected range for aeronautical navigation, promising little or no
interference under all circumstances.
2.4.3 Calculating Positions
The coordinates are calculated according to the WGS84 coordinates system.
To calculate its position, a receiver needs to know the accurate time. The
satellites are equipped with extremely accurate atomic clocks, and the
receiver uses an internal crystal oscillator-based clock that is continually
updated using the signals from the satellites.
The receiver identifies each satellite's signal by its distinct C/A code pattern,
and then measures the time delay for each satellite. To do this, the receiver
produces an identical C/A sequence using the same seed number as the
satellite. By lining up the two sequences, the receiver can measure the delay
and calculate the distance to the satellite, called the pseudorange. [1]
The orbital position data from the Navigation Message is then used to
calculate the satellite's precise position. Knowing the position and the distance
of a satellite indicates that the receiver is located somewhere on the surface
of an imaginary sphere centered on that satellite and whose radius is the
distance to it. When four satellites are measured simultaneously, the
intersection of the four imaginary spheres reveals the location of the receiver.
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Final Project Report Final Project ReportEarth-based users can substitute the sphere of the planet for one satellite by
using their altitude. Often, these spheres will overlap slightly instead of
meeting at one point, so the receiver will yield a mathematically most-
probable position (and often indicate the uncertainty). [1]
Calculating a position with the P(Y) signal is generally similar in concept,
assuming one can decrypt it. The encryption is essentially a safety
mechanism; if a signal can be successfully decrypted, it is reasonable to
assume it is a real signal being sent by a GPS satellite. In comparison, civil
receivers are highly vulnerable to spoofing since correctly formatted C/A
signals can be generated using readily available signal generators. [RAIM]
features will not help, since RAIM only checks the signals from a navigational
perspective. [1]
2.4.4 Accuracy And Error Sources
The position calculated by a GPS receiver requires the current time, the
position of the satellite and the measured delay of the received signal. The
position accuracy is primarily dependent on the satellite position and signal
delay. [1]
To measure the delay, the receiver compares the bit sequence received from
the satellite with an internally generated version. By comparing the rising and
trailing edges of the bit transitions, modern electronics can measure signal
offset to within about 1% of a bit time, or approximately 10 nanoseconds for
the C/A code. Since GPS signals propagate nearly at the speed of light, this
represents an error of about 3 meters. This is the minimum error possible
using only the GPS1 C/A signal. [1]
Position accuracy can be improved by using the higher-speed P(Y) signal.
Assuming the same 1% accuracy, the faster P(Y) signal results in accuracy of
about 30 centimeters. [1]
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Final Project Report Final Project ReportElectronics errors are one of several accuracy-degrading effects outlined in the table below. When taken together, autonomous civilian
GPS horizontal position fixes are typically accurate to about 15 meters (50 ft). These effects also reduce the more precise P(Y) code's
accuracy. [1]
Sources of errors
Source Effect
Ionospheric effects ± 5 meter
Ephemeris errors ± 2.5 meter
Satellite clock errors ± 2 meter
Multipath distortion ± 1 meter
Tropospheric effects ± 0.5 meter
Numerical errors ± 1 meter or less
Table 2.1 Sources Of Error (Source [1])
2.4.4.1. Atmospheric Effects
Changing atmospheric conditions change the speed of the GPS signals as
they pass through the Earth's atmosphere and ionosphere. Correcting these
errors is a significant challenge to improving GPS position accuracy. These
effects are minimized when the satellite is directly overhead, and become
greater for satellites nearer the horizon, since the signal is affected for a
longer time. Once the receiver's approximate location is known, a
mathematical model can be used to estimate and compensate for these
errors. [1]
Because ionospheric delay affects the speed of radio waves differently based
on frequency, a characteristic known as dispersion, both frequency bands can
be used to help reduce this error. Some military and expensive survey-grade
civilian receivers compare the different delays in the L1 and L2 frequencies to
measure atmospheric dispersion, and apply a more precise correction. This
can be done in civilian receivers without decrypting the P(Y) signal carried on
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Final Project Report Final Project ReportL2, by tracking the carrier wave instead of the modulated code. To facilitate
this on lower cost receivers, a new civilian code signal on L2, called L2C, was
added to the Block [IIR-M] satellites, first launched in 2005. It allows a direct
comparison of the L1 and L2 signals using the coded signal instead of the
carrier wave. [1]
The effects of the ionosphere are generally slow-moving, and can be
averaged over time. The effects for any particular geographical area can be
easily calculated by comparing the GPS-measured position to a known
surveyed location. This correction is also valid for other receivers in the same
general location. Several systems send this information over radio or other
links to allow L1 only receivers to make ionospheric corrections. The
ionospheric data are transmitted via satellite in Satellite Based Augmentation
Systems such as WAAS, which transmits it on the GPS frequency using a
special (PRN) 10, so only one antenna and receiver are required. [1]
Humidity also causes a variable delay, resulting in errors similar to
ionospheric delay, but occurring in the troposphere. This effect is much more
localized, and changes more quickly than the ionospheric effects, making
precise compensation for humidity more difficult. Altitude also causes a
variable delay, as the signal passes through fewer atmospheres at higher
elevations. Since the GPS receiver measures altitude directly, this is a much
simpler correction to apply. [1]
2.4.4.2. Multipath Effects
GPS1 signals can also be affected by multipath issues, where the radio
signals reflect off surrounding terrain; buildings, canyon walls, hard ground,
etc. These delayed signals can cause inaccuracy. A variety of techniques,
most notably narrow correlator spacing, have been developed to mitigate
multipath errors. For long delay multipath, the receiver itself can recognize the
wayward signal and discard it. To address shorter delay multipath from the
signal reflecting off the ground, specialized antennas may be used. Short
delay reflections are harder to filter out since they are only slightly delayed,
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Final Project Report Final Project Reportcausing effects almost indistinguishable from routine fluctuations in
atmospheric delay. [1]
Multipath effects are much less severe in moving vehicles. When the GPS
antenna is moving, the false solutions using reflected signals quickly fail to
converge and only the direct signals result in stable solutions. [1]
2.4.4.3. Ephemeris and Clock Errors
The navigation message from a satellite is sent out only every 12.5 minutes.
In reality, the data contained in these messages tend to be "out of date" by an
even larger amount. Consider the case when a GPS satellite is boosted back
into a proper orbit; for some time following the maneuver, the receiver’s
calculation of the satellite's position will be incorrect until it receives another
ephemeris update. The onboard clocks are extremely accurate, but they do
suffer from some clock drift. This problem tends to be very small, but may add
up to 2 meters (6 ft) of inaccuracy. [1]
This class of error is more "stable" than ionospheric problems and tends to
change over days or weeks rather than minutes. This makes correction fairly
simple by sending out a more accurate almanac on a separate channel. [1]
2.4.4.4. Selective Availability
The GPS includes a feature called (SA) that introduces intentional errors
between 0 meters and up to a hundred meters (300 ft) into the publicly
available navigation signals, making it difficult to use for guiding long range
missiles to precise targets. Additional accuracy was available in the signal, but
in an encrypted form that was only available to the United States military, its
allies and a few others, mostly government users. [1]
SA typically added signal errors of up to about 10 meters (30 ft) horizontally
and 30 meters (100 ft) vertically. The inaccuracy of the civilian signal was
deliberately encoded so as not to change very quickly, for instance the entire
eastern U.S. area might read 30 m off, but 30 m off everywhere and in the
same direction. In order to improve the usefulness of GPS for civilian
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Final Project Report Final Project Reportnavigation, (Differential GPS) was used by many civilian GPS receivers to
greatly improve accuracy. [1]
In the 1990s, the (FAA) started pressuring the military to turn off SA
permanently. This would save the FAA millions of dollars every year in
maintenance of their own radio navigation systems. The military resisted for
most of the 1990s, but SA was eventually "discontinued"; the amount of error
added was "set to zero" in 2000 following an announcement by U.S. President
Bill Clinton, allowing users access to an undegraded L1 signal. Per the
directive, the induced error of SA was changed to add no error to the public
signals (C/A code). Selective Availability is still a system capability of GPS,
and error could be in theory reintroduced at any time. In practice, in view of
the hazards and costs this would induce for US and foreign shipping, it is
unlikely to be reintroduced, and various government agencies, including the
FAA have stated that it is not intended to be reintroduced. [1]
The US military has developed the ability to locally deny GPS (and other
navigation services) to hostile forces in a specific area of crisis without
affecting the rest of the world or its own military systems. [1]
2.4.4.5. GPS Jamming
Jamming of any radio navigation system, including satellite based navigation,
is possible. The U.S. Air Force conducted GPS jamming exercises in 2003
and they also have GPS anti-spoofing capabilities. In 2002, a detailed
description of how to build a short range GPS L1 C/A jammer was published
in Phrack issue 60 by an anonymous author. There has also been at least one
well-documented case of unintentional jamming, tracing back to a
malfunctioning TV antenna preamplifier. If stronger signals were generated
intentionally, they could potentially interfere with aviation GPS receivers within
line of sight. According to John Ruley, of AVweb, "IFR pilots should have a
fallback plan in case of a GPS malfunction". (RAIM), a feature of some
aviation and marine receivers, is designed to provide a warning to the user if
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Final Project Report Final Project Reportjamming or another problem is detected. GPS signals can also be interfered
with by natural geomagnetic storms, predominantly at high latitudes. [1]
2.4.4.6. Relativity
For GPS satellites, General Relativity predicts that the atomic clocks at GPS
orbital altitudes will tick faster by about 45,900 ns/day because they are in a
weaker gravitational field than atomic clocks on Earth's surface. Special
Relativity (SR) predicts that atomic clocks moving at GPS orbital speeds will
tick slower by about 7,200 ns/day than stationary ground clocks. Rather than
have clocks with such large rate differences, the satellite clocks are reset in
rate before launch to compensate for these predicted effects. [1]
For GPS satellites, this discrepancy is 38 microseconds per day. To account
for this, the frequency standard on-board the satellites are given a rate offset
prior to launch, making it run slightly slower than its desired frequency on
Earth, at 10.22999999543 MHz instead of 10.23 MHz, a difference of -4.465
parts in 1010. The atomic clocks on board the GPS satellites are precisely
tuned, making this a practical engineering application of the scientific theory of
relativity in a real-world system. [1]
Another relativistic effect to be compensated for in GPS observation
processing is the Sagnac effect.. The Lorentz transformation between the two
systems modifies the signal run time, a correction having opposite algebraic
signs for satellites in the Eastern and Western celestial hemispheres. Ignoring
this effect will produce an East-West offset in the absolute position solution on
the order of tens of meters. [1]
The error introduced by relativistic effects can be as much as 15 meters. The
GPS system also makes adjustments for the relativistic drift of the atomic
clocks in the satellites. Parts of this correction are carried out in the satellites
and parts in the receiver.
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2.4.5 GPS Time and Date
While most clocks are synchronized to Coordinated Universal Time (UTC),
the Atomic clocks on the satellites are set to "GPS time." The difference is
that GPS time is not corrected to match the rotation of the Earth, so it does
not contain leap seconds or other corrections which are periodically added to
UTC. GPS time was set to match Coordinated Universal Time (UTC) in 1980,
but has since diverged. The lack of corrections means that GPS time remains
synchronized with the International Atomic Time (TAI). [1]
The GPS navigation message includes the difference between GPS time and
UTC, which is 14 seconds as of 2006. Receivers subtract this offset from GPS
time to calculate UTC and 'local' time. New GPS units may not show the
correct UTC time until after receiving the UTC offset message. The GPS-UTC
offset field can accommodate 255 leap seconds (eight bits) which, at the
current rate of change of the earth's rotation, is sufficient to last until the year
2330. [1]
The GPS date is expressed as a week number plus a day-of-week number,
as opposed to the year, month, and day format of the Gregorian calendar.
The week number is transmitted in a ten-bit field, and so it becomes zero
again every 1,024 weeks (19.7 years). GPS week zero started at 00:00:00
UTC (00:00:19 TAI) on January 6, 1980 and the week number became zero
again for the first time at 23:59:47 UTC on August 21, 1999 (00:00:19 TAI on
August 22, 1999). In order to determine the current Gregorian date, a GPS
receiver must be provided with the approximate Gregorian date (to within
3,584 days) in order to correctly translate the GPS date signal. [1]
2.4.6 GPS Time Transfer
GPS is at the present time the most competent system for time transfer, the
distribution of Precise Time and Time Interval (PTTI). The system uses time of
arrival (TOA) measurements for the determination of user position. A precisely
timed clock is not essential for the user because time is obtained in addition to
position by the measurement of TOA of FOUR satellites simultaneously in
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Final Project Report Final Project Reportview. If altitude is known (i.e. for a surface user), then THREE satellites are
sufficient. If time is being kept by a stable clock (say, since the last complete
coverage), then TWO satellites in view are sufficient for a fix at known
altitude. If the user is, in addition, stationary or has a known speed then, in
principle, the position can be obtained by the observation of a complete pass
of a SINGLE satellite. This could be called the "transit" mode, because the old
TRANSIT system uses this method. In the case of GPS, however, the
apparent motion of the satellite is much slower, requiring much more stability
of the user clock.[4]
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2.5 DIFFERENTIAL GPS
Differential correction techniques are used to enhance the quality of location
data gathered using global positioning system (GPS) receivers. Differential
correction can be applied in real-time directly in the field or when
postprocessing data in the office. Although both methods are based on the
same underlying principles, each accesses different data sources and
achieves different levels of accuracy. Combining both methods provides
flexibility during data collection and improves data integrity. [4]
Picture 2.1 Real-Time Differential GPS (Source [4])
The differential GPS (DGPS) requires that a GPS receiver, which is known as
the base station, should be set up on a precisely known location. The base
station receiver calculates its position based on satellite signals and compares
this location to the known location. The difference is then applied to the GPS
data recorded by the roving GPS receiver.
2.5.1. Real-Time DGPS
Real-time DGPS occurs when the base station calculates and broadcasts
corrections for each satellite as it receives the data. The correction is received
by the roving receiver via a radio signal if the source is land based or via a
satellite signal if it is satellite based and applied to the position it is calculating.
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Final Project Report Final Project ReportAs a result, the position displayed and logged to the data file of the roving
GPS receiver is a differentially corrected position.[4]
A nonprofit scientific and educational organization, Radio Technical
Commission for Maritime Services (RTCM), that serves all aspects of radio
communications, radio navigation, and related technologies, defined the
differential data protocol for relaying GPS correction messages from a base
station to a field user. Its Special Committee 104 (RTCM SC-104) format
recommendations define the correction message format. Each correction
message includes data about the station position and health, satellite
constellation health, and the correction to be applied.
2.5.2. Satellite Differential Services
Another method for obtaining real-time differential correction data in the field
is by using geostationary satellites. This system obtains corrections from more
than one reference station. Reference stations collect the base station GPS
data and relay this data in RTCM SC-104 format to a Network Control Center,
which sends the information to a geostationary satellite for verification. The
verified information is sent to the roving GPS receiver to ensure it obtains
GPS positions in real time. [4]
The Wide Area Augmentation System, or WAAS, is being developed by the
Federal Aviation Administration (FAA) to provide precision guidance to aircraft
at airports and airstrips that currently lack these capabilities, using a system of
satellites and ground stations that provide GPS signal corrections. Although
not yet approved for aviation use, it is available to civilian users. WAAS is
broadcast from geostationary satellites so the signal is often available in areas
where other DGPS sources are not available. Two commercial satellite
differential service providers, Thales Survey LandStar (formerly Racal
LandStar) and OmniSTAR Inc., use a control hub where reference station
data is checked, formatted, and uploaded to a geostationary satellite for
rebroadcasting to subscribers. [5]
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Final Project Report Final Project ReportDGPS radio beacon systems operate in many parts of the world. These
stations—part of a large network that covers coastal areas, navigable rivers,
and, more recently, inland agricultural areas—are used for marine navigation.
However, these beacons have a range of a few hundred kilometers inland and
can provide free real-time differential accuracy in the one-meter range,
depending on the GPS receiver and the distance from the radio beacon. [4]
2.5.3. Reprocessing Real-Time Data
Some GPS manufacturers provide software that can correct GPS data that
was collected in real time. This is important for GIS data integrity. When
collecting real-time data, the line of sight to the satellites can be blocked or a
satellite can be so low on the horizon that it provides only a weak signal,
which causes spikes in the data. Reprocessing real-time data removes these
spikes and allows real-time data that has been used in the field for navigation
or viewing purposes to be made more reliable before it is added to a GIS [5]
2.5.4. Postprocessing Correction
Differentially correcting GPS data by post processing uses a base GPS
receiver that logs positions at a known location and a rover GPS receiver that
collects positions in the field. The files from the base and rover are transferred
to the office processing software, which computes corrected positions for the
rover's file. This resulting correct file can be viewed in or exported to a GIS. [6]
There are many permanent GPS base stations currently operating throughout
the world that provide the data necessary for differentially correcting GPS.
Depending on the technology preferred by the base station owner, this data
can be downloaded from the Internet or via a bulletin board system (BBS).
Because base station data is consistent and very reliable because base
stations usually run 24 hours, seven days a week, it is ideal for many GIS and
mapping applications. Sources of base station data for postprocessing fall into
four categories—public sources, commercial sources, Web-based services,
and base station ownership. Before purchasing a GPS receiver, it is best to
identify the source of base station data. [5]
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2.5.4.1. Public Sources
Government agencies worldwide collect and store base data. However,
there are different laws for public to access the government data. These
laws vary from country to country as well as between different government
agencies in the same country. Agencies that collect differential data have
legitimate concerns, such as legal liability and cost recovery, which may
affect the decisions regarding offering this data to the public.
2.5.4.2. Commercial Sources
Some consulting firms and universities collect base data. Generally, this
data is purchased at per hour or daily rates. By browsing the Internet, by
calling local base station distributors, or by talking to a local GPS sales
representative the information on these services can be obtained. This can
often be the most cost-effective way to obtain data.
2.5.4.3. Web-Based Services
In this the GPS data is given to a service with some processing criteria.
The GPS data is processed and then returned back. This is an easy and
economical way to process GPS data. This approach is very helpful when
there is no time to train GPS users that how to processes data. So instead
training the users this approach is being used.
2.5.4.4. Base Station Ownership
This is the most flexible way to obtain base data for post processing but it
has additional setup costs because two GPS receivers must be purchased
and managed. If large amounts of data will be collected, the investment is
often worthwhile.
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2.5.5. Summary
To attain accuracy levels on the order of one to 10 meters, differential
correction is essential. The three main methods currently used for ensuring
data accuracy are real-time differential correction, reprocessing real-time
data, and post-processing. Each method will achieve similar levels of
accuracy, so the decision regarding which technique is appropriate will
depend on factors such as project specifications, the end use of the data, and
the sources available for differential correction.
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2.6 CONTENTS RECEIVED FROM GPS RECEIVER Text Mode
Text-out Interface I/O format is used to get the required data from the GPS
device. So when the GPS receiver attach to the serial port of PC, the data
seen on HyperTerminal is in the following format.
But we will retrieve the selected area of the out put as coordinates for our use.
This whole string will further divide in to two parts N and E which are our
latitude and longitude.
An example is shown below shows the output in text-out format.
@07 02 19 14 33 55 N3126446 E07417081 G 007 +00214 E0000
N0000 U0000
@yy mm dd hh mm ss Latitude Longitude error Altitude EWSpd
NSSpd VSpd
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Final Project Report Final Project ReportEach item is of fixed length making parsing by just counting the number of
characters an easy task. It is grouped by use permitting a digital camera, for
example, to just read the first 30 characters and report the time and position.
A more formal description of the fields is:
FIELD DESCRIPTION:
WIDTH: NOTES:
Sentence start 1 Always '@'
TIME
Year 2 Last two digits of UTC year
Month 2 UTC month, "01".."12"
Day 2 UTC day of month, "01".."31"
Hour 2 UTC hour, "00".."23"
Minute 2 UTC minute, "00".."59"
Second 2 UTC second, "00".."59"
POSITION
Latitude hemisphere
1 'N' or 'S'
Latitude position 7WGS84 ddmmmmm, with an implied decimal after the 4th digit
Longitude hemishpere
1 'E' or 'W'
Longitude position 8WGS84 dddmmmmm with an implied decimal after the 5th digit
Position status 1
'd' if current 2D differential GPS position'D' if current 3D differential GPS position'g' if current 2D GPS position'G' if current 3D GPS position'S' if simulated position'_' if invalid position
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CHAPTER NO.3
MICROCONTROLLER
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3.1 MICROCONTROLLER
3.1.1. What Is A Microcontroller?
A MCU is a computer-on-a-chip. It is a type of microprocessor emphasizing
self-sufficiency and cost-effectiveness, in contrast to a general-purpose
microprocessor that can be purchased for a very low price. A typical MCU
contains all the memory and interfaces needed for a simple application,
whereas a general purpose microprocessor requires additional chips to
provide these functions. A MCU is a single integrated circuit, commonly with
the following features: [7]
Central processing unit - ranging from small and simple 4-bit processors to
sophisticated 32- or 64-bit processors
Input/output interfaces such as serial ports
Peripherals such as timers and watchdog and signal conversion circuits
RAM for data storage
ROM, EPROM, EEPROM or Flash memory for program storage
Clock generator - often an oscillator for a quartz timing crystal, resonator
or RC circuit
MCU have traditionally been programmed using assembly language of the
target chip. Different MCU’S from different manufactures have different
assembly languages. Assembly language consists of short mnemonic
descriptions of instruction sets. These mnemonics are difficult to remember
the program developed for one MCU cannot be used for MCU from any other
company. The solution for this problem is to use high level languages. This
makes a programming much simpler task and the programs are usually more
readable, portable and easier to maintain. We use C language to program our
MCU as we are quite familiar with the syntax and it’s easy as compared to
assembly. [7]
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3.1.2. PIC16F877
PIC16F877 is a 40 pin MCU. The device contain a serial port,32 I/O lines,
interrupt capability up to 14 sources, two timers,8k* 14 words of flash
memory, 368*8 bytes of data memory, 256*8 bytes of EEPROM data
memory, dedicates pins for 12C protocols following devices, 10 A/D built in
converters and built in PWM pins for analogue outputs. There are many
reasons to choosing the PIC16F877, including the compatibility with the family
and the ease of erasing and reprogramming the device. [38]
All the necessary support components are included, together with a Power
and Programming LED for easy status indication. Plus a reset switch for
program execution and a RS232 connection for data transfer to and from a
standard RS232 port, available on most computers. [38]
The PIC16F877 Controller is the ideal solution for use as a standard controller
in many applications. The small compact size combined with easy program
updates and modifications makes it ideal for use in machinery and control
systems, such as alarms, card readers, real-time monitoring applications and
much more. Save time and money, by simply building your ancillary boards
and monitoring circuits around this inexpensive & easy to use controller. [38]
3.2 USE OF MICROCONTROLLER IN VTS
3.2.1 Gps Interfacing With Microcontroller
The GPS receiver has an output serial port at its hack. The output of digital
data from the serial port is of RS232 nature. So it can be directly connected to
the serial port of PC. Due to excellent input output capabilities of USART of
PIC MCU, RS232 standard serial data can be easily received by MCU with
inserting MAX232 level shifter IC.
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One of the most popular forms of communication between electronic devices
is serial communication. There are two major types of serial communication
asynchronous and synchronous. The RSIN, RSOUT, SERIN and SEROUT
commands are used to send and receive asynchronous serial data. While the
SHIN and SHOUT commands are for use with synchronous communications.
The term asynchronous means to ‘no clock’. ‘More specifically, asynchronous
serial communication’ means data is transmitted and received without the use
of separate ‘clock’ line. Data can be sent using as few as two wires, one for
data and one for ground. The PC’s serial ports (also call COM ports or RS232
ports) use asynchronous serial communication.
The other kind of serial communication, synchronous, uses at least three
wires, one for clock, one for data and one for ground. RS232 is the electrical
specification for the signals that PC serial ports use. Unlike standard TTL
logic, where 5 volts is a logic1 and 0 volts is logic 0, RS232 uses-12volts for
logic 1 and +12 volts for logic 0. This specification allows communication over
longer wire lengths without amplification.
Most circuits that work with RS232 use a line driver/receiver (transceiver).
This component does two things.
Converts the ± 12 volts of RS232 to TTL compatible 0 to 5 volt levels
Invert the voltage levels, so that 5 volts= logic 1 and 0 volts = logic 0
By far, the most common line driver device is the MAX232 from MAXIM. Semiconductor, because of the excellence IO capabilities of the PIC micro
range of devices, and the adoption of TTL levels on most modern PC serial
port, a line driver is often unnecessary unless long distance are involved
between the transmitter and the receiver. Instead a simple current limiting
resistor is all that’s required.
It should be remembered that when using line transceiver such as the
MAX232, the serial mode (polarity) is inverted in the process of converting the
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Final Project Report Final Project Reportsignal levels, however, if using the direct connection, the mode is untouched.
This is the single most common cause of errors when connecting serial
devices.
Asynchronous serial communication relies on precise limiting. Both the sender
and receiver must be set for identical timing. This is commonly expressed in
bps called BAUDRATE. Beside the baud rate parity bit, data bits and stop bit
are the other attributes, which are required to agree on both receiving and
transmitting end.
Parity is a simple error checking feature. On Transmitter End Even parity
(Compiler Default) means that it counts the no of 1s in the outgoing byte and
using the parity bit to make that number even.
For example, if it is sending the 7-bit value: %0011010 it sets the parity bit to
1 to make an even numbers of 1s (four).
The receiver also counts the data bits to calculate what the parity bit should
be. If it matches the parity bit received, the serial receiver assumes that the
data was received correctly. Of course, this is not necessarily true, since two
incorrectly received bits could make parity seem correct when the data was
wrong, or the parity bit itself could be bad when the rest of the data was
incorrect. Parity errors are not detected on the receiver side.
Normally, the receiver determines how to handle an error. In a more robust
application, the receiver and transmitter might be set up in such that the
receiver can request a re-send of data that was received with the parity error.
Because of its complexity, the serial communication can rather difficult to work
with at times.
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Broadly speaking a MCU is a single chip microprocessor which contains
data and program memory, serial and parallel port I/O lines (Pins),
timers, external and internal interrupts, all integrated into a single chip
that can be purchased for a very low price.
We will use the MCU to get the data from the GPS device and send that
data to the GPRS enabled device.
The MCU sends and receives the data with the help of “TX” and “RX”
Modules.
The TX Module is used to transmit the data to the GPRS enabled
device which is transmitted with the help of AT commands i.e. used to
handle the mobile device. We can do any function which we are doing
on our mobile phone; normally for this we will use serial communication
where the data is stored on to a buffer before it is sent to the GPRS
enabled mobile.
With respect to RX module it is used to receive the data from the GPS
device. The GPS device automatically sends the data through the serial
port after regular intervals and the MCU get that data using the RX
Module. In order to get data continuously, we will get the data from the
buffer; leave it empty in order to get the data again for the transmittion.
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3.3 SCHEMATIC DIAGRAM
3.4 ARCHITECTURE OF PIC16F87X FAMILY PIC MCU’S use Harvard architecture. That simply means that the memory on
the PIC is divided into program memory and data memory. The device uses
separate buses to communicate with each memory type. [38]
The data memory in the PIC can be divides into general purpose RAM and
special functional REGISTERS. [38]
There are three memory blocks in each of the PIC16f87X MCU’S. The
Program memory and Data memory have separate buses so that concurrent
access can occur. The PIC16F87X devices have a 13-bit program counter
capable of addressing an 8k x 14 program memory space. The PIC16F877/76
devices have 14 words of Flash Program memory that work above the
physically implemented address that will cause a wraparound. [38]
PIC16F877A CORE FEATURES [38]
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Final Project Report Final Project Report High performance RISC CPU
Only 35 single word instructions to learn
All single cycle instructions except from program branches which are
two cycle
Operating Speed: DC-20mhz clock input DC-200 ns instruction cycle
Up to 8k x 14 words of Flash Memory, 368*8 bytes of data memory,
256*8 bytes of EEPROM data memory
Pin out compatible to the PIC16C73B/74B/76/77
Interrupt capability(up to 14 sources)
Single 5V In-Circuit Serial Programming Capability
Processor read/write access to program memory
wide operating voltage range : 2.0V to 5.5 V
High sink /source current: 25mA
Commercials, Industrial and Extended temperature ranges
Low-Power consumption:
< 0.6mA typical @ 3V, 4 MHZ
1 µA typical standby current
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3.5 ARCHITECTURAL DIAGRAM OF Pic16f87x Family [38]
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3.6 PIN DIAGRAM OF PIC16F87X [38]
3.6.1. PORT A functions [38]
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This buffer is a Schmitt Trigger input when configured as the external
interrupt. This buffer is a Schmitt Trigger input when used in serial
programming mode. Low voltage ICSP programming (LVP) is enabled by
default, which disables the RB3 I/O function. LVP must be disabled to enable
RB3 as an I/O pin and allow maximum compatibility to the other 28-pin and
40-pin mid-range devices.
3.6.3. PORT C function [38]
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Final Project Report Final Project Report3.6.4. PORT D function [38]
3.6.5. PORT E function [38]
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3.7 CONTROLLER SPECIFICATIONS [38]
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CHAPTER NO.4
GPRS MOBILE
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4.1 - GPRS
The General Packet Radio Service (GPRS) network is an "always on", private
network for data. It uses the existing GSM network to transmit and receive
TCP/IP based data to and from GPRS mobile devices. Private IP addresses
are typically dynamically assigned within the network to mobile devices.
However, Access Point Names (APN's) provide a gateway route to other
networks such as the Internet, WAP services or private corporate networks.
Firewalls typically reside at the APN to isolate the public and private networks.
IP addresses allocated to mobile GPRS devices are therefore not
addressable from outside the GPRS network (e.g. from the Internet) without
specialized services or infrastructure. [9]
4.1.1. Gprs Features
The General Packet Radio Service (GPRS) is a new non-voice value added
service that allows information to be sent and received across a mobile
telephone network. It supplements today's Circuit Switched Data and Short
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Final Project Report Final Project ReportMessage Service (SMS).GPRS is not related to GPS (the Global Positioning
System), a similar acronym that is often used in mobile contexts. GPRS has
several unique features which can be summarized as: [8]
4.1.1.1. Speed
Theoretical maximum speeds up to 171.2 kilobits per second (kbps) are
achievable with GPRS using all eight timeslots at the same time. This is about
three times as fast as the data transmission speeds possible over today's
fixed telecommunications networks and ten times as fast as current Circuit
Switched Data services on GSM networks. By allowing information to be
transmitted more quickly, immediately and efficiently across the mobile
network, GPRS may well be a relatively less costly mobile data service
compared to SMS and Circuit Switched Data. [8]
4.1.1.2. Immediacy
GPRS facilitates instant connections whereby information can be sent or
received immediately as the need arises, subject to radio coverage. No dial-
up modem connection is necessary. This is why GPRS users are "always
connected". Immediacy is one of the advantages of GPRS when compared to
Circuit Switched Data. High immediacy is a very important feature for time
critical applications such as remote credit card authorization where it would be
unacceptable to keep the customer waiting for even thirty extra seconds. [8]
4.1.1.3. New Applications, better Applications
GPRS facilitates many new applications that have not previously been
available over GSM limitations in speed of Circuit Switched Data (9.6 kbps)
and message length of the SMS (Characters). GPRS will fully enable the
Internet applications you are used to on your desktop from web browsing to
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Final Project Report Final Project Reportchat over the mobile network. Other applications for GPRS, profiled later, file
transfer and home automation the ability to remotely access and control in-
home appliances & machine. . [8]
4.1.1.4. Service Access
To use GPRS, users specifically need: [8]
a mobile phone or terminal that supports GPRS (existing GSM phones
do NOT support GPRS)
a subscription to a mobile telephone network that supports GPRS
Use of GPRS must be enabled for that user. Automatic access to the
GPRS may be allowed by some mobile network operators, others will
require a specific opt-in
knowledge of how to send and/ or receive GPRS information using
their specific model of mobile phone, including software and hardware
configuration (this creates a customer service requirement)
A destination to send or receive information through GPRS. Whereas
with SMS this was often another mobile phone, in the case of GPRS, it
is likely to be an Internet address, since GPRS is designed to make the
Internet fully available to mobile users for the first time. From day one,
GPRS users can access any web page or other Internet applications-
providing an immediate critical mass of uses.
4.1.2. Key Network Features Of GPRS
GPRS involves a packet based air interface on the existing circuit switched
GSM network. This gives the user an option to use a packet-based data
service. To supplement circuit switched network architecture with packet
switching is quite a major upgrade. However lately the GPRS standard is
delivered in a very elegant manner- with network operators needing only to
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Final Project Report Final Project Reportadd a couple of new infrastructure and upgrade software to some existing
network elements with GPRS. [8]
Spectrum efficiency
Packet switching means that GPRS radio resources are used only when
users are actually sending or receiving data. Rather than dedicating a radio
channel to a mobile data user for a fixed period of time, the available radio
resource can be concurrently shared between several users. This efficient use
of scarce radio resources means that large numbers of GPRS users can
potentially share the same bandwidth and be served from a single cell. The
actual number of users supported depends on the application being used and
how much data is being transferred. Because of the spectrum efficiency of
GPRS, there is less need to build in idle capacity that is only used in peak
hours. GPRS therefore lets network operators maximize the use of their
network resources in a dynamic and flexible way, along with user access to
resources and revenues. [8]
GPRS should improve the peak time capacity of a GSM network since it simultaneously: [8]
Allocates scarce radio resources more efficiently by supporting virtual
connectivity
Immigrates traffic that was previously sent using Circuit Switched Data
to GPRS instead, and reduces SMS Center and signaling channel
loading by migrating some traffic that previously was sent using SMS to
GPRS instead using the GPRS/ SMS interconnect that is supported by
the GPRS standards.
Internet Aware
For the first time, GPRS fully enables Mobile Internet functionality by allowing
inter-working between the existing Internet and the new GPRS network. Any
service that is used over the fixed Internet today- File Transfer Protocol (FTP),
web browsing, chat, email, telnet- will be as available over the mobile network
because of GPRS. In fact, many network operators are considering the
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Final Project Report Final Project Reportopportunity to use GPRS to help become wireless Internet Service Providers
in their own right. [8]
The WWW becoming the primary communications interface- people access
the Internet for entertainment and information collection, the intranet for
accessing company information and connecting with colleagues and the
extranet for accessing customers and suppliers. These are all derivatives of
the World Wide Web aimed at connecting different communities of interest.
There is a trend away from storing information locally in specific software
packages on PCs to remotely on the Internet. When you want to check your
schedule or contacts, instead of using something like "Act!", you go onto the
Internet site such as a portal. Hence, web browsing is a very important
application for GPRS. [8]
Because it uses the same protocols, the GPRS network can be viewed as a
sub-network of the Internet with GPRS capable mobile phones being viewed
as mobile hosts. This means that each GPRS terminal can potentially have its
own IP address and will be addressable as such. [8]
Supports TDMA and GSM
It should be noted right that the General Packet Radio Service is not only a
service designed to be deployed on mobile networks that are based on the
GSM digital mobile phone standard. The IS-136 Time Division Multiple
Access (TDMA) standard, popular in North and South America, will also
support GPRS. This follows an agreement to follow the same evolution path
towards third generation mobile phone networks concluded in early 1999 by
the industry associations that support these two network types. [8]
4.1.3. Limitations Of Gprs
It should already be clear that GPRS is an important new enabling mobile
data service which offers a major improvement in spectrum efficiency,
capability and functionality compared with today's non-voice mobile services.
However, it is important to note that there are some limitations with GPRS.
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Final Project Report Final Project Reporti. Limited Cell Capacity for all Users
GPRS does impact a network's existing cell capacity. There are only limited
radio resources that can be used for different uses- use for one purpose
precludes simultaneous use for another. For example, voice and GPRS calls
both use the same network resources. The extent of the impact depends upon
the number of timeslots, if any, that are reserved for exclusive use of GPRS.
However, GPRS does dynamically manage channel allocation and allow a
reduction in peak time signaling channel loading by sending short messages
over GPRS channels instead. [9]
ii. Speed much lower in reality
Achieving the theoretical maximum GPRS data transmission speed of 172.2
kbps would require a single user taking over all eight timeslots without any
error protection. Clearly, it is unlikely that a network operator will allow all
timeslots to be used by a single GPRS user. Additionally, the initial GPRS
terminals are expected be severely limited- supporting only one, two or three
timeslots. . The reality is that mobile networks are always likely to have lower
data transmission speeds than fixed networks. [9]
Relatively high mobile data speeds may not be available to individual mobile
users until Enhanced Data rates for GSM Evolution (EDGE) or Universal
Mobile Telephone System (3GSM) are introduced. [9]
iii. Support for GPRS Mobile Terminate by Terminals is not ensured
At the time of writing, there has been no confirmation from any handset
vendors that mobile terminated GPRS calls (i.e. receipt of GPRS calls on the
mobile phone) will be supported by the initial GPRS terminals. Availability or
not of GPRS MT is a central question with critical impact on the GPRS
business case such as application migration from other non-voice bearers.
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Final Project Report Final Project ReportBy originating the GPRS session, users confirm their agreement to pay for the
delivery of content from that service. This origination may well be performed
using a Wireless Application Protocol (WAP) session using the WAP micro
browser that will be built into GPRS terminals. However, mobile terminated IP
traffic might allow unsolicited information to reach the terminal. Internet
sources originating such unsolicited content may not be chargeable. A
possible worse case scenario would be that mobile users would have to pay
for receiving unsolicited junk content. This is a potential reason for a mobile
vendor NOT to support GPRS Mobile Terminate in their GPRS terminals.
iv. Suboptimal Modulation
GPRS is based on a modulation technique known as Gaussian minimum-shift
keying (GMSK). EDGE is based on a new modulation scheme that allows a
much higher bit rate across the air interface- this is called eight-phase-shift
keying (8 PSK) modulation. Since 8 PSK will also be used for 3GSM, network
operators will need to incorporate it at some stage to make the transition to
third generation mobile phone systems. [9]
v. Transit Delays
GPRS packets are sent in all different directions to reach the same
destination. This opens up the potential for one or some of those packets to
be lost or corrupted during the data transmission over the radio link. The
GPRS standards recognize this inherent feature of wireless packet
technologies and incorporate data integrity and retransmission strategies.
However, the result is that potential transit delays can occur. [9]
Because of this, applications requiring broadcast quality video may well be
implemented using High Speed Circuit Switched Data (HSCSD). HSCSD is
simply a Circuit Switched Data call in which a single user can take over up to
four separate channels at the same time. Because of its characteristic of end
to end connection between sender and recipient, transmission delays are less
likely. [9]
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Final Project Report Final Project Reportvi. No Store and Forward
Whereas the Store and Forward Engine in the Short Message Service is the
heart of the SMS Center and key feature of the SMS service, there is no
storage mechanism incorporated into the GPRS standard, apart from the
incorporation of interconnection links between SMS and GPRS. [9]
4.1.4. Applications For Gprs
A wide range of corporate and consumer applications are enabled by non-
voice mobile services such as SMS and GPRS. This section will introduce
those that are particularly suited to GPRS. [9]
i. Chat
Chat can be distinguished from general information services because the
source of the information is a person with chat whereas it tends to be from an
Internet site for information services. The "information intensity"- the amount
of information transferred per message tends to be lower with chat, where
people are more likely to state opinions than factual data. In the same way as
Internet chat groups have proven a very popular application of the Internet,
groups of likeminded people- so called communities of interest- have begun to
use non-voice mobile services as a means to chat and communicate and
discuss. [9]
Because of its synergy with the Internet, GPRS would allow mobile users to
participate fully in existing Internet chat groups rather than needing to set up
their own groups that are dedicated to mobile users. Since the number of
participants is an important factor determining the value of participation in the
newsgroup, the use of GPRS here would be advantageous. GPRS will not
however support point to multipoint services in its first phase, hindering the
distribution of a single message to a group of people. As such, given the
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primary bearer for chat applications in the foreseeable future, [9]
ii. Text and Visual Information
A wide range of content can be delivered to mobile phone users ranging from
share prices, sports scores, weather, flight information, news headlines,
prayer reminders, lottery results, jokes, horoscopes, traffic and location
sensitive services and so on. This information need not necessarily be textual-
it may be maps or graphs or other types of visual information. [9]
The length of a short message of 160 characters suffices for delivering
information when it is quantitative. When the information is of a qualitative
nature however, such as a horoscope or news story, 160 characters is too
short. GPRS will likely be used for qualitative information services when end
users have GPRS capable devices, but SMS will continue to be used for
delivering most quantitative information services. Interestingly, chat
applications are a form of qualitative information that may remain delivered
using SMS, in order to limit people to brevity and reduce the incidence of
spurious and irrelevant posts to the mailing list that are a common occurrence
on Internet chat groups. [9]
iii. Still Images
Still images such as photographs, pictures, postcards, greeting cards and
presentations, static web pages can be sent and received over the mobile
network as they are across fixed telephone networks. It will be possible with
GPRS to post images from a digital camera connected to a GPRS radio
device directly to an Internet site, allowing near real-time desktop publishing.
iv. Moving Images
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Over time, the nature and form of mobile communication is getting less textual
and more visual. The wireless industry is moving from text messages to icons
and picture messages to photographs and blueprints to video messages and
movie previews being downloaded and on to full blown movie watching via
data streaming on a mobile device. [9]
Sending moving images in a mobile environment has several vertical market
applications including monitoring parking lots or building sites for intruders or
thieves, and sending images of patients from an ambulance to a hospital.
Videoconferencing applications, in which teams of distributed sales people
can have a regular sales meeting without having to go to a particular physical
location, is another application for moving images. [9]
v. Web Browsing
Using Circuit Switched Data for web browsing has never been an enduring
application for mobile users. Because of the slow speed of Circuit Switched
Data, it takes a long time for data to arrive from the Internet server to the
browser. Alternatively, users switch off the images and just access the text on
the web, and end up with difficult to read text layouts on screens that are
difficult to read from. As such, mobile Internet browsing is better suited to
GPRS. [9]
vi. Document Sharing / Collaborative working
Mobile data facilitates document sharing and remote collaborative working.
This lets different people in different places work on the same document at
the same time. Multimedia applications combining voice, text, pictures and
images can even be envisaged. These kinds of applications could be useful in
any problem solving exercise such as fire fighting, combat to plan the route of
attack, medical treatment, advertising copy setting, architecture, journalism
and so on. Even comments on which resort to book a holiday at could benefit
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Final Project Report Final Project Reportfrom document sharing to save everyone have to visit the travel agent to
make a decision. [9]
vii. Audio
Despite many improvements in the quality of voice calls on mobile networks
such as Enhanced Full Rate (EFR), they are still not broadcast quality.
Leaving a mobile phone on, or dictating to a mobile phone, would simply not
give sufficient voice quality to allow that transmission to be broadcast or
analyzed for the purposes of background noise analysis or voice printing,
where the speech autograph is taken and matched against those in police
storage. Since even short voice clips occupy large file sizes, GPRS or other
high speed mobile data services are needed. [9]
viii. Job dispatch
Non-voice mobile services can be used to assign and communicate new jobs
from office-based staff to mobile field staff. Customers typically telephone a
call center whose staffs take the call and categorize it. Those calls requiring a
visit by field sales or service representative can then be escalated to those
mobile workers. Job dispatch applications can optionally be combined with
vehicle positioning applications- such that the nearest available suitable
personnel can be deployed to serve a customer. GSM non-voice services can
be used not only to send the job out, but also as a means for the service
engineer or sales person can keep the office informed of progress towards
meeting the customer’s requirement. The remote worker can send in a status
message such as "Job 12complete, on my way to 11”. [9]
The 160 characters of a short message are sufficient for communicating most
delivery addresses such as those needed for a sale, service or some other job
dispatch application such as mobile pizza delivery and courier package
delivery. However, 160 characters do require manipulation of the customer
data such as the use of abbreviations such as "St" instead of "Street". Neither
does 160 characters leave much space for giving the field representative any
information about the problem that has been reported or the customer profile.
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Final Project Report Final Project ReportThe field representative is able to arrive at the customer premises but is not
very well briefed beyond that. This is where GPRS will come in to allow more
information to be sent and received more easily. With GPRS, a photograph of
the customer and their premises could, for example, be sent to the field
representative to assist in finding and identifying the customer. As such, we
expect job dispatch applications will be an early adopter of GPRS-based
communications. [9]
ix. Corporate E-mail
With up to half of employees typically away from their desks at any one time,
it is important for them to keep in touch with the office by extending the use of
corporate email systems beyond an employee's office PC. Corporate email
systems run on Local Area computer Networks (LAN) and include Microsoft
Mail, Outlook, Outlook Express, Microsoft Exchange, Lotus Notes and Lotus
cc:Mail. [9]
Since GPRS capable devices will be more widespread in corporations than
amongst the general mobile phone user community, there are likely to be
more corporate email applications using GPRS than Internet email ones
whose target market is more general. [9]
x. Internet E-mail
Internet email services come in the form of a gateway service where the
messages are not stored, or mailbox services in which messages are stored.
In the case of gateway services, the wireless email platform simply translates
the message from SMTP, the Internet email protocol, into SMS and sends to
the SMS Center. In the case of mailbox email services, the emails are actually
stored and the user gets a notification on their mobile phone and can then
retrieve the full email by dialing in to collect it, forward it and so on.
Upon receiving a new email, most Internet email users do not currently get
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Final Project Report Final Project Reportnotified of this fact on their mobile phone. When they are out of the office, they
have to dial in speculatively and periodically to check their mailbox contents.
However, by linking Internet email with an alert mechanism such as SMS or
GPRS, users can be notified when a new email is received. [9]
xi. Vehicle positioning
This application integrates satellite positioning systems that tell people where
they are with non-voice mobile services that let people tell others where they
are. The Global Positioning System (GPS) is a free-to-use global network of
24 satellites run by the US Department of Defense. Anyone with a GPS
receiver can receive their satellite position and thereby find out where they
are. Vehicle positioning applications can be used to deliver several services
including remote vehicle diagnostics, ad-hoc stolen vehicle tracking and new
rental car fleet tariffs. [9]
The Short Message Service is ideal for sending Global Positioning System
(GPS) position information such as longitude, latitude, bearing and altitude.
GPS coordinates are typically about 60 characters in length. GPRS could
alternatively be used. [9]
xii. Remote LAN Access
When mobile workers are away from their desks, they clearly need to connect
to the Local Area Network in their office. Remote LAN applications
encompasses access to any applications that an employee would use when
sitting at their desk, such as access to the intranet, their corporate email
services such as Microsoft Exchange or Lotus Notes and to database
applications running on Oracle or Sybase or whatever. The mobile terminal
such as handheld or laptop computer has the same software programs as the
desktop on it, or cut down client versions of the applications accessible
through the corporate LAN. This application area is therefore likely to be a
conglomeration of remote access to several different information types- email,
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Final Project Report Final Project Reportintranet, and databases. This information may all be accessible through web
browsing tools, or require proprietary software applications on the mobile
device. The ideal bearer for Remote LAN Access depends on the amount of
data being transmitted, but the speed and latency of GPRS make it ideal. [9]
xiii. File Transfer
As this generic term suggests, file transfer applications encompass any form
of downloading sizeable data across the mobile network. This data could be a
presentation document for a traveling salesperson, an appliance manual for a
service engineer or a software application such as Adobe Acrobat Reader to
read documents. The source of this information could be one of the Internet
communication methods such as FTP (File Transfer Protocol), telnet, http or
Java- or from a proprietary database or legacy platform. Irrespective of source
and type of file being transferred, this kind of application tends to be
bandwidth intensive. It therefore requires a high speed mobile data service
such as GPRS, EDGE or 3GSM to run satisfactorily across a mobile network.
4.1.5. Optimal Bearer By Application
Currently, corporate applications that use the Short Message Service are few
and far between. The reasons are the relatively older age of corporate mobile
phone users and their lower price sensitivity, particularly since the employer
usually pays mobile phones bills. Corporate users are less willing to learn how
to and make the effort to send a short message- they tend to use voice as
their primary communications method. Instead, the vast majority of SMS
usage is accounted for by consumer applications. It is not uncommon to find
90% of the total SMS traffic accounted for by the consumer applications that
have been described. Until GPRS terminals are consumer oriented, SMS will
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Final Project Report Final Project Reportcontinue to be bearer for most consumer applications. However, since GPRS
will be incorporated into high end mobile phones initially, it will be used more
for corporate applications. [9]
Whatever the application, the Internet will become the primary
communications interface. Previously, application developers wrote
proprietary applications that worked with proprietary host terminals and often
proprietary rugged terminal operating systems. For example, instead of
corporate applications such as service engineering using platform and
software specific interfaces, the mobile workers such as service engineers will
access an intranet page using their GPRS capable terminal and fill in an
electronic form. People increasingly use a web browser to access publicly
available data on the Internet itself, the extranet for access to the data of
business partners and other external collaborators and the intranet to access
internal employee information. As such, all work will be carried out through the
web interface. [9]
Often, by designing applications to minimize the effects of the limitations of
existing mobile services- such as the length of a short message or the speed
of a Circuit Switched Data call- existing non-voice mobile services can be
successfully used for mobile working. However, many non-voice applications
are graphics intensive and the new faster data services will allow BETTER
VERSIONS of today's existing non-voice applications. For example, instead of
occasional information messages with SMS, information services via GPRS or
3GSM will be more akin to the "push" Internet channels we see on Active PC
Desktops today. Instead of the slow transmission of small video images, real-
time broadcast quality images will be transmittable. Instead of using SMS to
notify Internet users of new email, the whole email will be sent, and full-blown
Internet access will be possible. The same applications will be more
immediate and convenient for users. [9]
The use of SMS has prepared customers for nonvoice applications using
GPRS and other nonvoice services and most of the applications envisaged for
GPRS already exist in some form today. It is therefore an important question
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Final Project Report Final Project Reportto consider what the preferred bearer for each application will be- GPRS,
Circuit Switched Data or SMS. [9]
Ranking of Initial GPRS Traffic Generators
With any new service, it is an important part of the business case to estimate
what the applications for that technology will be. We believe that the business
case for any network operator for GPRS is compelling- it confers a huge
increase in capability for a relatively small investment. The more popular
applications using GPRS are expected to be: [9]
Ranking Application Bearer1 Corporate email GPRS2 Internet email GPRS/ SMS3 Information Services- Qualitative GPRS4 Job Dispatch GPRS5 Remote LAN Access GPRS6 File Transfer GPRS7 Web browsing GPRS8 Still Images9 Moving Images GPRS / HSCSD10 Chat GPRS/ SMS11 Home Automation GPRS12 Document Sharing/Collaborative Working GPRS13 Audio GPRS
The first of the applications listed will be popular partly because they are
widespread over fixed telephone networks but have previously not been
readily or fully available over GSM networks. The Internet and email are
already in place today- GPRS will allow them to be made fully wire free and
available everywhere. The applications ranked further down the list lack
current popularity in the fixed communications world and lack widespread
availability of specific software solutions. [9]
Whilst these applications are technically feasible or high speed mobile data
services such as GPRS, the volume of usage is dependent upon commercial
factors such as pricing. It is expected that GPRS will incorporate volume-
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Final Project Report Final Project Reportbased charging such that only the data sent will be charged for, paving the
way for widespread usage amongst customers with GPRS capable devices.
4.1.6. GPRS Network Nodes
Enabling GPRS on a GSM network requires the addition of two core modules,
the Gateway GPRS Service Node (GGSN) and the Serving GPRS Service
Node (SGSN). As the word Gateway in its name suggests, the GGSN acts as
a gateway between the GPRS network and Public Data Networks such as IP
and X.25. GGSN also connect to other GPRS networks to facilitate GPRS
roaming. The Serving GPRS Support Node (SGSN) provides packet routing
to and from the SGSN service area for all users in that service area. [9]
In addition to adding multiple GPRS nodes and a GPRS backbone, some
other technical changes that need to be added to a GSM network to
implement a GPRS service. These include the addition of Packet Control
Units; often hosted in the Base Station Subsystems, mobility management to
locate the GPRS Mobile Station, a new air interface for packet traffic, new
security features such as ciphering and new GPRS specific signaling. [9]
4.2 - GPRS DEVICE
4.2.1. What is a GPRS Modem?
A GPRS modem is a GSM modem that additionally supports the GPRS
technology for data transmission. We already discuss GPRS above. It is a
packet-switched technology that is an extension of GSM. (GSM is a circuit-
switched technology.) A key advantage of GPRS over GSM is that GPRS has
a higher data transmission speed. [10]
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Final Project Report Final Project ReportGPRS can be used as the bearer of SMS. If SMS over GPRS is used, an
SMS transmission speed of about 30 SMS messages per minute may be
achieved. This is much faster than using the ordinary SMS over GSM, whose
SMS transmission speed is about 6 to 10 SMS messages per minute. A
GPRS modem is needed to send and receive SMS over GPRS. Note that
some wireless carriers do not support the sending and receiving of SMS over
GPRS. [10]
If you need to send or receive MMS messages, a GPRS modem is typically
needed.
4.2.2. Public Internet Access To GPRS Devices
GPRS devices are not addressable from the internet. The Internet and GPRS
are designed for client driven applications and are therefore directly supported
by a gprs router or gprs modems dial out mode of operation. Due to APN
firewalls, remote GPRS server devices can only be addressed by a private
network solution or via more complex VPN technology. [10]
4.2.3. Private Network Access To GPRS Devices
Although client GPRS devices can communicate with ease over Public and
Private networks, GPRS server devices require a static IP address. Network
Operators offer private APN's to corporate networks over Leased Lines or
VPN's, where IP address assignment is managed by the customer's corporate
Network e.g. using a radius server. Alternatively, Wireless Operators in some
countries offer private APN's with static IP address support thereby creating
customers their own private network within the GPRS network. These are
supported by the GPRS modem or GPRS routers "Always on" mode of
operation. [10]
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Final Project Report Final Project Report4.2.4. GPRS Mobile Device
There are a number of GPRS devices, each of which can offer GSM services
too, such as voice calls and SMS. [10]
A GPRS Mobile Phone
A GPRS Radio Card for a PC
A Hand held PC with an in-built GPRS Mobile
A remote machine enabled with a Comtech GPRS M2M device.
4.2.5. GPRS Classes Of GPRS Device
There are 3 classes of GPRS device being developed, of which only class B
is currently available: - [10]
Class A - Operates in GSM and GPRS modes at the same time, and
hold simultaneous voice and data sessions.
Class B - Operates in GSM and GPRS modes at the same time, and
but cannot hold simultaneous calls.
Class C - Can be active in either GSM or GPRS mode, but not at the
same time.
4.3 - AT COMMANDS
A series of machine instructions used to activate features on an intelligent
modem. Developed by Hayes Microcomputer Products and officially known as
the Hayes Standard AT Command Set, it is used entirely or partially by most
every modem manufacturer. AT is a mnemonic code for ATtention, which is
the prefix that initiates each command to the modem
At commands are used by Terminal Equipment to connect to the mobile
phone. The Terminal equipment‘s can be a microcontroller, computer etc.
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Final Project Report Final Project ReportThese are the set of commands described by RFC’s (required for commands)
of the Hayes‘s compatible modem. Some AT commands are not supported by
all Samsung GSM products or by all operators. Giving a command that is not
supported by a product cause an error response. All products do not support
all command parameters and using those parameters causes an error
response.
Computer use AT commands to communicate with modems, most
communications applications, however, have a user friendly interface that
hides these AT command s for the users. We can issue the AT commands
through our communication application. “AT” or “at” must be included at the
beginning of each command line. These AT commands can be issued to a
mobile phone using a utility in Microsoft Windows, Which is called
HyperTerminal. In AT commands jargon that is called Terminal Adapter (TA).
HyperTerminal is used to issue the AT commands to the mobile which is
connected to the serial port of the computer. Hyper Terminal can be
configured to send data to the special at different baud rates e. g 110, 300,
1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800,
921600 Bits per Second. Some AT commands are not supported by our
mobile phone. Giving a command, which is not supported by the mobile, gives
error response.
4.3.1. Important AT Commands
GPRS Commands
1. AT*EAPP (Application Function)
Requests the MT to perform an application function specified by <app>
and <subfunc>. The <subfunc> parameter specifies which function within
the specified application to call.
Syntax
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Final Project Report Final Project ReportAT*EAPP=<app1>[,<subfunc1>[,<text1>[,<text2>]]] and so on until the desired level app and sub functions are used
Parameters:<app>:
We are using app=3, web application to send data to the web server
2. AT+CGDCONT Define Packet Data Protocol (PDP)
Specifies the PDP context parameter values for a PDP context. This
command is used in conjunction with the +CGDATA command.
Syntax:
+CGDCONT=<cid>,<PDP_type>,<APN>,<PDP_addr>,<d_comp>,<h_c
omp>, <pd1>[,…[,<pdN>]]
Defined values:
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Final Project Report Final Project Report<cid>: (PDP Context Identifier) a numeric parameter (1-4) which specifies
a particular PDPcontext definition. The parameter is local to the TE-MT
interface and is used in other PDP context-related commands.
<PDP_type>: (Packet Data Protocol type) a string parameter which
specifies the type of packet data protocol.
IP Internet Protocol
PPP Point to Point Protocol
<APN>: (Access Point Name) a string parameter, which is a logical name
that is used to select the GGSN or the external packet data network. If the
value is null or omitted, then the subscription value will be requested.
<PDP_address>: a string parameter that identifies the MT in the address
space applicable to the PDP. If the value is null or omitted, then a value
may be provided by the TE during the PDP startup procedure or, failing
that, a dynamic address will be requested.
<d_comp>: a numeric parameter that controls PDP data compression
0 - off (default if value is omitted)
1 – on
Other values are reserved.
<h_comp>: a numeric parameter that controls PDP header compression
0 - off (default if value is omitted)
1 – on
Other values are reserved.
Example
AT +CGDCONT=1, "IP", "internet"; +GCDCONT=2, "IP", "abc.com"
OK
3. AT+CGQREQ Quality of Service Profile (Requested)
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Final Project Report Final Project ReportUsed to specify a Quality of Service Profile that is used when the MT
sends an Activate PDP Context Request message to the network.
Syntax:
+CGQREQ=<cid>,<precedence>,<delay>,<reliability>,<peak>,<mean>
Defined values:
<cid>: a numeric parameter which specifies a particular PDP context
definition.
<precedence>: a numeric parameter which specifies the precedence
class.
<delay>: a numeric parameter which specifies the delay class.
<reliability>: a numeric parameter which specifies the reliability class.
<peak>: a numeric parameter which specifies the peak throughput class.
<mean>: a numeric parameter which specifies the mean throughput class.
Example:
AT +CGQREQ=1,1,4,5,2,14
OK
4. AT+CGQMIN Quality of Service Profile (Minimum Acceptable)
Used to specify a minimum acceptable profile that is checked by the MT
against the negotiated profile returned in the Activate PDP Context Accept
message.
Syntax:
+CGQMIN=<cid>,<precedence>,<delay>,<reliability>,<peak>,<mean>
Defined values:
<cid>: a numeric parameter which specifies a particular PDP context .
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Final Project Report Final Project Report<precedence>: a numeric parameter which specifies the precedence
class.
<delay>: a numeric parameter which specifies the delay class.
<reliability>: a numeric parameter which specifies the reliability class.
<peak>: a numeric parameter which specifies the peak throughput class.
<mean>: a numeric parameter which specifies the mean throughput class.
Example:
AT +CGQMIN=1,1,4,5,2,31
OK
5. AT+CGATT GPRS Attach or Detach
The execution command is used to attach the MT to, or detach the MT
from, the GPRS service. Any active PDP contexts will be automatically
deactivated when the attachment state changes to detached.
Syntax:
+CGATT= [<state>]
Defined values:
<state>: indicates the state of GPRS attachment
0 – detached
1 – attached
Other values are reserved and will result in an ERROR response to
the execution command.
Example:
AT +CGATT=1
OK
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Final Project Report Final Project Report
CHAPTER NO.5
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MAP DIGITIZATION
5.1 - INTRODUCTION
Digital Map is a computer-readable representation of a geographic area that
can be displayed or analyzed by a digital computer. This is in contrast to an
analog "paper" map.[11]
Digitization is used where the dimensions are not present or where it is not
having importance. Digitization is also used in the mapping field as on of the
first step to get the base map. [11]
The drawing has to be scanned with more accuracy as to minimize the error
factor. It might require a cleaning process if it is blue print, sepia or in the old
drawings where there are lot of stains. [11]
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Final Project Report Final Project ReportDigitization process looks simple but it in reality it requires more accuracy as
there no dimension present so picking up the points is very important. With
our vast experience in digitization we have developed our own methodology
where we make use of the automatic software as well as the manual method.
In order for a map to be recognizable from a computer, it has to be transformed from
the analogical to a digital format. This transformation is called Digitization and it can
be performed in two formats: vector and raster.
In a vector format the map is divided in parts, which are appointed to vectors. These
vectors are defined by an x,y coordinate system, according to which every point of the
analogical map is assigned to one of the digital format. In a raster format the map is a
raster/table consisting of pixels1. In this way every pixel of the map is described by its
location and the intensity of radiation of light . With this method, we are able to know
about thematic information, like names, symbols, colors etc. [11]
According to the method of transformation, vector or raster, different digitizing
devices are used. The one used in vector formats is called a Digitizer, the other used
in raster formats is called a Scanner. [11]
Digitizer
A digitizer is a hardware device connected to a computer, so as to transform an analog
map to a digital map in vector format. It consists of a tablet with dimensions
according to the type (A4 to A0) and a pointing device (mouse).The map is placed
firmly on the tablet and the pointing device is dragged on the areas to be digitized. By
clicking on the pointing device, the coordinates of the element are transferred in the
computer, through a metal grid. The accuracy of the coordinates transferred through
digitization varies according to the device and lies between 0,5mm to 0,125mm. [11]
Scanner
A scanner is also a hardware device connected to a computer in order to transform a
map in raster format. The digitizing process is as follows: a map, design or photo to
be scanned is placed steadily on the scanner surface. During the scanning, radiation is
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Final Project Report Final Project Reportapplied to the area scanned. The transmitted radiation is either reflected or penetrated
through the map (depending on the material from which it is constructed). Then it is
recollected from a sensor, which counts the wavelength or the intensity of radiation,
and in this way it analyses the map into pixels. The result is the perception of different
colors, in a scale from 0 to 255. [11]
Besides the different format .vector or raster. in which the map is transformed
according to the device, the digitizer allows the selective digitizing of specific parts of
the map, for instance roads, unlike the scanner, which scans the entire surface placed
on it but has the advantage of colors’ Recognition and speed of scanner. [11]
5.1.2 - GPS Maps
GPS systems do not work by magic, even if it might seem so at times. In fact,
each one contains special GPS maps controlled by mapping software which
allows it to match the global position of the unit, in real time, against a map of
the vicinity in which it finds itself. As you might expect, there are a few
sources if you need GPS maps or mapping software for the purpose of
navigation, not all of them free, and not all of them reliable. Therefore it pays
to be careful in making the right choices when it comes to navigation. [6]
The first source is your old map cupboard. With the right software, you can
create GPS maps from a real one. This will involve scanning the mapping
software into your computer, and using an appropriate software package to
convert the picture into a series of co-ordinates, heights and other information
needed to build a digital version for navigation. [6]
If you do not have a scanner, or a suitable map, then you will have to
purchase GPS maps for navigation with your particular brand of GPS
receiver. Prices will vary according to the base map used, and the amount of
information or mapping software that the supplier has put on the digital map. [6]
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Final Project Report Final Project ReportFor example, GPS maps designed for use with urban and highway navigation
systems, including cities, roads, and other features will be comparatively
expensive when put alongside those which have only the key geographic
features – heights, rivers and lakes. So it all depends on the content in the
mapping software. [6]
This may be enough for the hiker or climber, after all they will not need GPS
maps with every possible detail for navigation, and so can opt for the freely
available, or cheaper variety. Usually this is not an option available to owners
of vehicle based GPS systems, such as aviation, maritime or highway
vehicles, who will need to buy the mapping software from their GPS
manufacturer. [6]
5.1.3 - Digitization of Maps
This process is extremely appealing, there is a downside to the scanning of
maps: low levels of resolution; lack of standards; the size of memory required
to store the files; and, the impermanence associated with the software and
hardware used in the process. [16]
Maps and digital imaging
Digital imaging technology is a relatively new process, with its widespread use
coming only in the 1990s with improvements in high resolution scanning;
lower costs for the scanning and storage of images; the spread of high-speed,
high-bandwidth networks; and, the emergence of the World Wide Web. The
basic tools needed to digitize a document are a computer, scanner, and
software to control the scanner and manipulate the images once they are
scanned. If the image is going to be put online for wider access, additional
software may be required. [16]
The importance of getting a good scan from a document on the initial scan
cannot be emphasized strongly enough. In some cases, an item may only be
available for one scan, or, the document may be so fragile that it cannot afford
to be scanned multiple times. Additionally, a quality scan saved in an archival
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image, information can then be transferred to other formats as desired. [16]
Following are the key determinants in obtaining a high-quality scan:
1) Resolution
2) Bit Depth/Dynamic Range
3) Image Enhancement
4) Compression
5) Metadata
Resolution:
The number of pixels used to represent an image; often measured as dots per
square inch (dpi). In grayscale and color scanning both resolution and bit
depth combine to play significant roles in image quality. Resolution is a
measurement of clarity, or detail, and can refer either to an image file, or, the
device, such as a monitor, used to display an image. Central to image quality
is not the capturing of a document at the highest resolution possible, but
rather, to scan at a level that ensures adequate capture of the information
content of the original document and the creation of a moderately sized file. [16]
Bit Depth/Dynamic Range:
Bit depth is the number of colors or shades of gray (grayscale) that can be
represented in a digital image. Dynamic range is a measurement of the
number of bits used to represent each pixel in an image and is used to
express the full range of tonal variations between the lightest and darkest
areas of a document. A scanner's capability to capture a complete range of
tones is dependent upon its bit depth and dynamic range. The greater the bit
depth, the greater number of grayscale or color tones that can be
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Final Project Report Final Project Reportrepresented. Black and white images are usually scanned using eight or
sixteen bits, while twenty-four bits and higher are used for color images. [11]
Image enhancement:
The use of software programs to improve image capture. Standard
enhancement software allows the user to rotate; crop; alter brightness or
contrast; and stitch together Tagged Image File Format (TIFF) images for
large documents requiring multiple scans. While the use of some of
enhancement features is necessary to provide a suitable image, too much
dependence on image altering software raises questions concerning the
authenticity and fidelity of an image. [11]
Compression:
The reduction of file size in order to save storage space. Digital images
captured at high resolutions produce large files. To counter this, several steps
are commonly followed to help reduce file size. First is the scanning of an
image at the highest feasible resolution and then saving the scanned image to
a lossless compression mechanism file, such as TIFF, to create an archival
image. Then, from the archival image, a lossy compression mechanism, such
as Joint Photographic Experts Group (JPEG) can be used to reduce the size
needed for a file's processing, storage, and transmission. A determining factor
in defining an appropriate level of compression is the balancing of file size and
resulting storage requirements with quality needs and the limits of the display
hardware and network speeds. The greater the image quality, the more
storage space it will occupy; the scanning process will be costlier and longer;
and, more memory will be required to display the image. [11]
The level of compression used may affect the quality of the image. An image
decompressed and viewed after lossless compression will be identical to its
original compression. Lossy compression results in some loss of data, and
therefore image quality are reduced. Images do not respond to compression
in an identical way. As an image is compressed, particular kinds of visual
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Final Project Report Final Project Reportcharacteristics, such as subtle tonal variations, or unintended visual effects
may appear. In other instances, no noticeable change results from the use of
lossy compression. A point to consider when determining resolution and
compression ratios is that the monitor a user views the image with will not be
calibrated the same as the monitor used when the image is digitized; thus,
any resolution finer than the resolution of the user's monitor is wasted. [16]
Metadata:
Data that describes an information resource and which assists in the locating
and accessing of information about the resource. Metadata includes a number
of elements, such as title, author, and date and place of creation. [11]
5.1.4 - Map Projections
Once a reference datum has been determined the elevation of any point can
be accurately determined, and it will correlate to the elevation of any point on
the earth's surface that has the same elevation and is using the same datum.
But…how do we accurately represent the X and Y coordinates of that point?
This question leads to one of the fundamental problems of mapmaking…how
do we represent all or part of an ellipsoid object on a flat piece of paper? The
answer to this question is a bit complicated, but understanding it is
fundamental to understanding what maps actually represent [14]
In order to represent the surface of the earth on a flat piece of paper, the map
area is projected onto the paper. There are many different types of
projections, each with its own strengths and weaknesses. [14]
The simplest (and easiest to visualize) projection is a planar projection. To
understand this type of projection, imagine inserting a piece of paper through
the earth along the equator. Now imagine that the earth is semi-transparent
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Final Project Report Final Project Reportand we could shine a flashlight oriented along the (geographic) polar axis
through the earth. [14]
5.1.5 - Distortions
Each of the different types of projections has strengths and weaknesses.
Knowledge of these different advantages and disadvantages for a particular
map projection will often help in which map to choose for a particular project.
The basic problem inherent in any type of map projection is that it will result in
some distortion of the ‘ground truth’ of the area being mapped. [15]
There are four basic characteristics of a map that are distorted to some
degree, depending on the projection used. These characteristics include
distance, direction, shape, and area. The only place on a map where there
is no distortion is along the trace of the line that marks the intersection of our
‘paper’ with the surface of the earth. [15]
Any place on the map that does not lie along this line will suffer some
distortion. Fortunately, depending on the type of projection used, at least one
of the four characteristics can generally be preserved. [15]
A conformal projection primarily preserves shape, an equidistant projection
primarily preserves distance, and an equal-area projection primarily preserves
area. [15]
5.1.6 - Map Scale
Individual topographic maps are commonly referred to as quadrangles (or
quads), with the name of the quadrangle giving an idea of the amount of area
covered by the map. The largest area covered by most topographic maps
used for scientific mapping purposes (i.e. geologic mapping, habitat studies,
etc.) are two degrees of longitude by one degree of latitude. [12]
A map of this size is referred to as a ‘two degree sheet’. One, two degree
sheet can be divided into four smaller quadrangles, each covering one degree
of longitude and 1/2 degree of latitude (‘one degree sheet’). [12]
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Final Project Report Final Project ReportEach one degree sheet is subdivided into eight ‘fifteen minute quadrangles’,
measuring fifteen minutes of latitude and longitude.
We can determine what type of quadrangle we are looking at by subtracting
the longitude value printed in the upper (or lower) left corner of the map from
the longitude printed in the upper (or lower) right corner of the map. This can
also be done using latitude values, just remember that a two degree sheet
only covers one degree of latitude and and one degree sheet only covers
thirty minutes of latitude. This information is also commonly printed in the
upper right hand corner of a map, under the title of the map. [12]
5.1.7 - Problems in the digitization of Maps
Maps are considered one of the most difficult items to scan. It is suggested
that beginning a scanning project not "begin with oversize maps, as the
combination of large dimensions and fine detail will challenge the best of
scanning systems and will defy effective presentation on the highest
resolution monitors available today." Many maps are too large to capture with
one scan and it is often difficult to scan a map in sections and then paste it
together. Regarding the fine detail of maps, contour lines and text are
sometimes as small as 1mm, meaning little contrast between the print and the
background. Another major difficulty is that maps usually lose their scale
when digitized and, as a result, the viewer is left without a firm understanding
of the distance between points on the map. [17]
It cannot be denied that the potential for the digital imaging of maps is great.
However, the technology is still relatively new and in the experimental phase,
and there exist a number of drawbacks that curb its use as a means of
preservation. Among some of the primary downsides with digital imaging are:
the lack of standards, and, a quickly changing technological base that
necessitates a migration policy and a financial commitment for future transfer
of files Despite the problems, there are currently an amazing array of digital
maps available via the Web and digital imaging holds great potential for
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Final Project Report Final Project Reportcapturing maps in the future. What follows below is an overview of the
imaging systems used to digitize maps. [17]
5.1.8 Conclusion: The Future of Map Reproduction
What does the future hold for the imaging of maps? Is it too early to proclaim
"microcartography" dead? Digitization offers color and an improved range of
access options. Images of maps captured at high resolution with 24-bit color
or 8-bit black and white provide a detailed copy of the map, which can be
saved in lossless TIFF format as an archival record. A wide variety of uses
can then be derived using JPEG compression or other space saving
compression methods. Once a file is placed on a server, anyone with a
computer and a modem can have access to a map. [17]
Despite their impressive traits, digital images cannot yet be considered the
clear choice for digitizing maps. Shortcomings still exist with cost, resolution,
and the always troubling question of permanence. However, headway is being
made with the above problems. The cost of memory is decreasing; methods
of compression are improving; and advances are continuously being made
with scanning and resolution. In the future it could very well be possible to use
digital cameras to image maps. [17]
With the increase in the digital imaging of library and archival collections has
come the lament that money is being diverted from a proven preservation
media (microforms) and rerouted to less-stable digital technologies. While the
microfilming of maps offers considerable advantages as a means of
preservation, is it that much of an advantage when it is an image that is
missing essential detail such as color? Digital imaging captures color and via
the Web raises awareness of the existence of older maps, which, as a result,
could increase the chances that heightened efforts will be made to preserve
the original map. Maps that would never be microfilmed, or, made the focus of
preservation efforts, are being digitized and, at least for the present, their
images are being saved. Despite shortcomings with digitization, the
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Final Project Report Final Project Reporttechnology will continue to be the choice for capturing the intricate detail
found on maps. [17]
5.2 - MAP DIGITIZATION PROCESS
For Digitizing the Map we have get a Map from Google Earth Which is of very
high Resolution and that is Required for the Map Digitization Because when
any Point is Plotted on to the Map only that area is highlighted that tell us that
where we are now for this we have to get a Map With high resolution other
wise the Position will be Blur and it will be problematic for the viewers of the
map to see where are they Now at the Moment We have taken the resolution
of 4800* 4026 from the premium version of the Google Earth.
The other way to get a high resolution image is not very difficult Process. For
this you have to get a very large Map and then cutting that Map into Small
Pieces that can be scanned and after scanning joining of the images with
each other as they are cut off from each other
Figure. The use of digital map in Vehicle Tacking System
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5.2.1 - Process To Digitize The Map
We will start digitizing the Map with the help of software which is called GPS Tools SDK
Step 1
In the step one we will load a BITMAP image because it gives support to the BITMAP images only
Step 2When the Map is loaded then there is the step to give name to your Map and this Name will be used in our application in which the Map handling is done
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Step 3
In this step you need to specify which coordinate system your raster map is using (for map projection).
i. Select a Country / Region.ii. Select if the coordinates are specified in lat/lon or easting/northing iii. Select the grid or datum.
The coordinate system chosen is that in which the map is conformal.Because so as we are using the Longitude and Latitude so we will select that Datagram and the Country Region is selected the International and the Datum is selected accordingly
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Step 4
In this step you must enter the geographic position which represents the X, Y position on the raster map.
In total you need to specify 3 coordinates the coordinate should be as far apart as possible for the best results. Try to place them in opposite corners.
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.
Step 5
Now you have to enter the scaling coordinate 2 of 3.As it is told earlier that for best results the points should be in opposite Direction for good Results
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Step 6
Now you have to enter scaling coordinate 3 of 3
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Step 7
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Final Project Report Final Project ReportWhen you are done with the above procedure, ‘Scanning Completed’ message will appear. Click ok to confirm it.
Step 8
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After that, we will have to verify our map. For this we have to click on to the known Position of the Map for Confirmation
Step 9
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The last step is to save your map. Go to the ‘File’ menu and then click on ‘Save Map as MPlib’ and your map will be saved.
Because the application only support this format
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CHAPTER NO.6
VEHICAL TRACKING WEBSITE DEVELOPMET
6.1 DEFINITION
A website (alternatively, Web site or web site) is a collection of Web pages,
images, videos and other digital assets that is hosted on a Web server,
usually accessible via the Internet or a LAN.
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Final Project Report Final Project ReportA Web page is a document, typically written in HTML that is almost always
accessible via HTTP, a protocol that transfers information from the Web
server to display in the user's Web browser.
All publicly accessible websites are seen collectively as constituting the
"World Wide Web".
The pages of websites can usually be accessed from a common root URL
called the homepage, and usually reside on the same physical server. The
URLs of the pages organize them into a hierarchy, although the hyperlinks
between them control how the reader perceives the overall structure and how
the traffic flows between the different parts of the sites. [37]
6.2 OVERVIEW
Websites are written in, or dynamically converted to, HTML (Hyper Text
Markup Language) and are accessed using a software program called a Web
browser, also known as an HTTP client. Web pages can be viewed or
otherwise accessed from a range of computer based and Internet enabled
devices of various sizes, including desktop computers, laptop computers,
PDAs and cell phones. [37]
A website is hosted on a computer system known as a web server, also called
an HTTP server, and these terms can also refer to the software that runs on
these system and that retrieves and delivers the Web pages in response to
requests from the website users. Apache is the most commonly used Web
server software (according to Netcraft statistics) and Microsoft's Internet
Information Server (IIS) is also commonly used. [37]
6.3 INTRODUCTION
The WWW becoming the primary communications interface- people access
the Internet for entertainment and information collection, the intranet for
accessing company information and connecting with colleagues and the
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Final Project Report Final Project Reportextranet for accessing customers and suppliers. These are all derivatives of
the World Wide Web aimed at connecting different communities of interest.
There is a trend away from storing information locally in specific software
packages on PCs to remotely on the Internet. When you want to check your
schedule or contacts, instead of using something like "Act!", you go onto the
Internet site such as a portal.
You should always remember that a web site is designed for visitors NOT for
yourself or your boss. And why do people come to your web site? They come
in search of information. Hence it is very important that you structure your site
in such a manner that visitors are able to locate information quickly. Put
yourself in the visitors' shoes.
6.4 WEBSITE ARCHITECTURE
One of the very first steps in developing a website is designing its
architecture. Like the blueprints of a building, the architecture outlines the
overall site.
For our system web server is used to host our site which contains the User
modules and the Administrator module and for this we need a static IP which
is used in order to interact our site, it also include a digital map.
So the Microcontroller gets the data from the GPS receiver and send data
with the help of AT commands through the mobile phone towards our website
where the data is stored in database, that data consists of Longitude,
Latitude, time and date, and then coordinates from the database are plotted
on the map.
6.5 WEBSITE MODULES
Our web server consist of two modules
Administrator Module
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Final Project Report Final Project Report User Module
In Administrative Module we basically handle the data base and the users.
Other then that, different functionalities are provided in this module which will
only be performed by the administrator and user will have no right or access
to those functionalities.
In User Module user can only see the location where it is and where it was, it
did not have access to the user management module and to the data base.
Other then that some limited functionalities are provided to the user to make
the website more user friendly.
6.6 MAPPING THE LATITUDE & LONGITUDE
To plot the position on the digitized map the latitude and the longitude are
required. The coordinates are taken from the GPS device, which then send
these coordinates to the microcontroller. The microcontroller gets the data
from GPS device and sends the data to the mobile phone using AT
commands. The mobile phone using GPRS sends the data to the web server
where the data is stored in the database.
The data which is sent from the microcontroller consist of longitude, latitude,
date and time. After receiving the data at web server the data is being
separated. The date and time are separated from the received data.
Longitude and latitude are then plotted on the digital map which is placed on
the web server. That plotted longitude and latitude will show the current
position of the vehicle.
There are three main pages along with the dlls provided by SDK that make
tracking possible on the digital map according to our requirement.
6.7 STRING SEPARATION (GPSSTR.ASPX)
The string which is send to our web server consists of the longitude, latitude,
date and time. At the web server we are separating all these things.
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All the process is done through following code:
The string which is send through microcontroller is received by the
“QueryString” method which then store the string in “gpsData” which is string
type variable. The microcontroller is also sending the Vehicle ID which is store
in the “user” which is a string type variable.
Dim gpsData As String Dim user, len As String gpsData = Request.QueryString("gpsStr") user = Request.QueryString("user")
The string which is send by the micro controller may also contain the dirty
data. Usually in start the data received contains the garbage data. To remove
that dirtiness or garbage data we perform some checks to ensure the validity
of the data.
“Index of “is basically used to check the occurrence of any specific character
i.e. at what position that character lies in the string.
len = gpsData.Length Dim at As String at = gpsData.IndexOf("@", 0)
Dim n As String n = gpsData.IndexOf("N", 0)
Dim ee As String ee = gpsData.IndexOf("E", 0)
Dim g As String g = gpsData.IndexOf("G", 0)
Dim gg As String gg = gpsData.IndexOf("g", 0)
Here the “If” condition ID applied to check the validity of the string. If the string
which is stored in the “gpsData” variable is valid then the further processing is
done on it. But if the string is invalid then the string will remain in the
“gpsData” variable and will be over write by the strings send by the micro
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Final Project Report Final Project Reportcontroller. As the string fulfills the “if” condition the further processing is done
on it.
If (len = 30 And at = -1 And n > 0 And ee > 0 And (g > 0 Or gg > 0)) Then
As the string consists of longitude, latitude, time and date, we have to
separate all these things. In the following code basically the date is being
separated.
Dim d1, d2, d3 As String Dim slash As String slash = "/" d1 = gpsData.Substring(0, 2) d2 = gpsData.Substring(2, 2) d3 = gpsData.Substring(4, 2)
Dim da As String da = String.Concat(d2, slash, d3)
Dim dat As Date dat = CDate(String.Concat(da, slash, d1))
Similarly the time is being separated from the string.
Dim t1, t2, t3 As String Dim col As String col = ":" t1 = gpsData.Substring(6, 2) t1 = t1 + 5 t2 = gpsData.Substring(8, 2) t3 = gpsData.Substring(10, 2)
Dim tim As String tim = String.Concat(t1, col, t2)
Dim time1 As Date time1 = CDate(String.Concat(tim, col, t3))
Here we are combing the date and time because we have to use both in our
sql query to get the latest gps data of the vehicle.
Dim datentime As Datedatentime = DateTime.Parse(Format(dat, "Long Date") & " " & Format(time1, "Long Time"))
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Final Project Report Final Project ReportSimilarly latitude and longitude is being separated from the string. We are
converting the longitude to the “toDecimal” function in order to make our data
in a readable format by our digitized map.
Dim lat As String lat = gpsData.Substring(13, 7) Dim latitude As Double latitude = toDecimal(lat)
Dim lon As String lon = gpsData.Substring(21, 8) Dim longitude As Double longitude = toDecimal(lon)
This is the function of “toDecimal” which is used in the conversion of the
longitude and latitude to the decimal format. A standard format which is
understandable to the map digitizes via Franson GPS.Net SDK
Private Function toDecimal(ByVal Pos As String) As DoubleDim Result As Double = (CDbl(Pos) / 1000)Dim Deg As Double = Math.Floor(Result / 100)Dim DecPos As Double = Math.Round(Deg + ((Result - (Deg * 100)) /60), 6)Return DecPosEnd Function
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6.8 MAP (map.aspx)
After the separation of longitude and latitude then these longitude and latitude
are marked on the digitized map. Which show the current position of the
vehicle. Most of the code of this page is the code provided by the SDK. In
order to use SDK code workable with our website we have to include two DLL
files provided by the sdk.
GpsToolsNet.dll
GpsViewNet.dll
6.9 IMAGE RENDER (imagerender.aspx)
Image render basically show the small area of map around the marked point
in the image box instead of showing the whole map. To upload full map huge
amount of time is required so image render only show the small portion of the
map. This page use all the code provided by the SDK.
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6.10 FUNCTIONS
Login
On the main page of the website their will be the login form. You can login as
an administrator or as a client by selecting any one of the choice. The access
to the next page will be granted on right login and password.
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6.10.1. Administrative Functions
By giving login and password on the main page of website the administrator
will be logged on and move on the next page where the administrator is
provided on with different functionalities.
The administrator is provided the functionalities of
Add Client
Change Password
Edit Client
Change Profile Information
Search Client
Ownership Transfer
Track Client
Other than this if there will be any incomplete vehicle profile then the message
will be displayed about the incomplete profile.
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Final Project Report Final Project Report6.10.1.1. Add Client
In add client form the administrator will first check the NIC. If the NIC number
is found in the database its mean that client already exist in the database. But
if NIC does not found then the administrator will proceed.
6.10.1.2. Change Password
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Final Project Report Final Project ReportIn this form the administrator is given the option of changing his/her password.
Administrator can change the old password and can setup a new password.
6.10.1.3. Edit Client
The administrator can first search the client by vehicle no or by name. After
the searched result the administrator can edit the client information.
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Final Project Report Final Project Report6.10.1.4. Change Profile Information
In this form all the changed profiles will be shown. So the administrator can have the record of all the changed profiles.
6.10.1.5. Search Client
The administrator can search the client by vehicle no or by name. After the
searched result the administrator can edit the client information.
6.10.1.6. Ownership Transfer
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Final Project Report Final Project ReportIn this form the administrator will transfer the ownership of one vehicle to the
other. The ownership will be transferred on the request of the client. If a client
wants to change the ownership then the client will send the request to the
administrator and administrator on client request will change the ownership
and save the changes.
6.10.1.7. Track Client
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Final Project Report Final Project ReportThe administrator can track the client vehicle through three different ways.
The client can be tracked through Real Time, by static or track by the date. Its
up to the administrator that through which mean he/she wants to track the
client.
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6.10.2. Client Functions
By giving login and password on the main page of website the client will be
logged on and move on the next page where the client is provided on with
different functionalities.
The client is provided with the functionalities of
Real Time Tracking
Static Tracking
Tracking by History
View Profile
Change Password
Edit Profile
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Final Project Report Final Project Report6.10.2.1. Real Time TrackingIn this form the current position of the client will be shown on the map. The
client can even zoom or can rotate the map within the given range according
to his/her own desire.
6.10.2.2. View Profile
The form will show the user profile which includes the user information and
the vehicle information. On this form the user can change the password and
can edit the user or vehicle information.
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Final Project Report Final Project Report6.10.2.3. Change PasswordIn this form the client is given the option of changing his/her password. Client
can change the old password and can setup a new password.
6.10.2.4.Edit ProfileThe client has the option to make changes in his/her profile. Through this form
the client can make changes in his/her profile and update them in the
database.
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Final Project Report Final Project Report6.10.2.5. Static TrackingIn static tracking the client can view or search the previous record. A calendar
is given on the form through which the user can select the desired date.
6.10.2.6. Tracking by History
In this all the tracking record of the specific user will be shown along with date
and time. And the user can track any of the record.
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Final Project Report Final Project Report
CHAPTER NO.7
CONCLUSION AND FUTURE WORK
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REFRENCES
GLOSSARY
Datum A datum is a network of monuments and reference points defining a mathematical surface from which geographic computations can be made.
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Final Project Report Final Project ReportAUC Authentication Center. It is responsible for generating random
key, and computes a signed response using ciphering algorithm.
BTS Base Transceiver Station. It handles the radio signals received from mobile stations.
DGPS A system to precisely determine the location of the Differential GPS receiver. This system uses a known stationary GPS receiver to track the same GPS signals as those picked up by adjacent receivers. Using FM radio transmissions, the system transmits error corrections to those receivers. [Section 1.4]
GPS Global Positioning System is a system designed by the United States Department of Defense, using satellites to locate one’s position on the earth. [Section 1.1]
Multipath Errors caused by the interference of a signal that has reachedError the receiver antenna by two or more different paths. This is usually caused by one path being bounced or reflected.
RS-232 RS-232 is a standard defined an asynchronous serial communication method. Data is transferred to and from the computer through a comm (communication) port that uses this RS-232 method of communication. [Section 6.1.3]
Waypoint A Route is made up from a number of waypoints, which break up the route into smaller segments. [Section 3.1.4.1]
BSC Base Station Controller. It controls the activity of several Base Transceiver Stations.
ETSI European Telecommunications Standard Institute. It is a non-profit organization aiming to produce telecommunication standards.
GSM Global System for Mobile communication. A 2G wireless network architecture that uses frequency band 900MHz, 1800MHz and 1900 MHz.
GPRS General Packet Radio Service. A 2.5G technology, builds on existing GSM network, and provides higher data transfer rate. Theoretic maximum data transfer rate is 171.2kbit/s
HLR Home Location Register. It holds information of registered users and activity status.
HSCSD High Speed Circuit Switched Data. It also builds on existing GSM network, and supports data rates up to 57.6kbit/s
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PCU Packet Control Unit. It is responsible for extracting and inserting packet data into the radio network
PPP Point-to-Point Protocol: A protocol that provides a serial line connectivity (that is, a dial-up with a modem) between two computers, between a computer and a network, or between two networks. PPP can handle several protocols simultaneously.
Protocol Rules and message formats for communication between computers in a network.
TCP Transmission Control Protocol: One of the two principal components of a TCP/IP protocol suite. TCP puts data into packets and provides reliable packet delivery across a network (packets arrive in order and are not lost).
UDP User Datagram Protocol: A TCP/IP protocol found at the network (internet) layer, along with the TCP protocol. UDP sends data down to the internet layer and to the IP protocol. Unlike TCP, UDP does not guarantee reliable, sequenced packet delivery. If data does not reach its destination, UDP does not retransmit as TCP does.
IP Internet Protocol: One of the two main parts of the TCP/IP protocol suite. IP delivers TCP and UDP packets across a network.
IP Address A 32-bit unique numeric address used by a computer on a TCP/IP network.
Port A number used by TCP and UDP to indicate which application is sending or receiving data.
SIM Subscriber Identity Module. A microchip that stores information of the subscriber.
SMS Short Message Service. It allows mobile users to send short alphanumeric messages through cell phones.
MSC Mobile service Switching Center. It acts as a switching node, switching from BSC to public fixed networks. It also provides authentication and security for GSM network.
MS Mobile Station. It represents the entire wireless device, such as handhelds and cell phones.
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Final Project Report Final Project ReportSGSN Serving GPRS Service Node. It provides authentication and
security for GPRS network. It also handles packet data passing from PCU.
UMTS Universal Mobile Telecommunications System. A 3G technology that will boost up the data transfer rate to approximately 2Mbit/s
VLR Visitor Location Register. It stores information of mobile users that are currently located in the geographical service area.
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