Gps Based Cab Monitoring System

GPS BASED CAB MONITORING SYSTEM

1. INTRODUCTION

In general, we have no correct mechanism to know the parameters like the route

in which a cab (vehicle) has travelled, where was it at a particular instant of time, with

what speed did it travel at that place and time and did it go to the desired place or not, we

don’t have a option rather than to believe the driver. The problem arises when the driver

doesn’t give us the exact authentic information.

If we want a cab (vehicle) to go to certain place, via certain route, with certain

speed within in certain time, later when we access the information about the journey, we

have to simply depend up on the driver for the information of the cab and the driver may

not give us the exact information about the journey and could use the cab (vehicle) for his

personal use.

The GPS BASED CAB MONITORING SYSTEM answers to all the problems

raised above. We can know the parameters like the distance travelled, time of the

journey, speed of the cab (vehicle), route adopted by the driver with out being dependent

on him.

We make use of a GPS modem, Multimedia card, Micro controller and a wireless

network (RF transceiver) and PC where the map of the route is given through Google

Earth.

Data logging mechanism is used here the data logging is done from GPS receiver

to the Multimedia card by interfacing them with a micro controller. The stored data in the

Multimedia card is sent to the pc through wireless (RF transceiver).The usage of wireless

network may increase the hardware complexity but avoids the usage of the cables which

is an irritating task to connect when the data needed to be transmitted to the pc, which is

used analyze the data graphically, using a software called Google Earth map.


2. PRINCIPLE OF OPERATION

The cab monitoring system deals with the speed, time, latitude and longitude of

cab which is obtained from GPS receiver and storing the data in the memory card and

transmit the data, in MMC to the PC with a wireless network, when ever we want to

access the data. The objective of this project is achieved by the mechanism called data

logging, is done from the GPS to the Multimedia card.

As it involves the identification of the cab it requires a Global Processing System

(GPS) to know the position of the cab. There are 24 satellites revolving around the earth’s

orbit, at least 3 satellites are required for the GPS receiver. When the GPS receiver is

exposed to at least 3 satellites it receives the data from the satellites i.e. latitude,

longitude, distance, speed, time, altitude. The receiver continuously gives the data until it

is switched off. A 5 V external power supply is given to the GPS receiver. The baud rate

of the GPS receiver is 4800 bits/sec

The data received is stored in the Multimedia card. Multimedia card is a device

which stores the data up to certain space. The MMC which we use, in this project is 2

GB. We have an option to format the MMC card. Whenever the data is required, it can be

taken from the MMC and it is valid until we manually delete or unless it is up to its full

capacity then the new data is replaced by the old existing data.

The GPS receiver is interfaced with the MMC by using a Microcontroller (PIC

18F452). The 5 V power supply is needed for the micro controller. The micro controller

in this project works in 2 modes, read and write, it reads the data from the GPS receiver

and writes in to the MMC. The PIC microcontroller supports SPI protocol, which enables

us to store the data in the MMC. The GPS receiver is interfaced with the Microcontroller

using a RS-232 protocol.

The data in the MMC is transferred to the PC using a wireless network i.e. RF

transceiver. There are two RF transceivers, one is connected to PC and other is connected

to Microcontroller. The data is presented in the Google Earth map graphically.


2.1 Block Diagram:

Fig 2.1 G.P.S Based Cab Monitoring System

The Major Building blocks of this Project

G.P.S receiver

MMC(multimedia card)

Microcontroller(18f452)

RF Transceiver

Power supply

Memory card interfacing

R.S 232

2.2 Description:

2.2.1 POWER SUPPLY:

The power supply unit is used to provide a constant 5V supply to different IC’s

this is a standard circuits using external 12VDC adapter and fixed 3-pin voltage regulator.

Diode is added in series to avoid Reverse voltage.


2.2.2 MICRO CONTROLLER:

The PIC 18f452 CMOS FLASH-based 8-bit microcontroller is upward

compatible with the PIC16C73B/74B/76/77, PIC16F873/874/876/877devices. It features

200 ns instruction execution, self programming, an ICD, 2 Comparators, 8 channels of 8-

bit Analog-to-Digital (A/D) converter, 2 capture/compare/PWM functions, a synchronous

serial port that can be configured as either 3-wire SPI or 2-wire I2C bus, a USART, and a

Parallel Slave Port.

2.2.3 G.P.S:

GPS is the only fully functional GNSS in the world. GPS uses the constellation of

between 24 and 32 Medium Earth Orbit satellites that transmit precise microwave sig-

nals, which enable GPS receivers to determine their current location, the time, and their

velocity. Its official name is NAVSTAR GPS.

2.2.4 MultiMedia Memory Card:

The Multimedia Card (MMC) is a flash memory card standard. A memory card or

flash memory card is solid-state electronic flash memory data storage device capable of

storing digital contents. The MMC is the smallest removable flash memory designed

specifically for digital applications, such as MP3 music players, digital video cameras,

mobile phones, voice recorder, video game consoles, and other electronics.


3. POWER SUPPLY

Power supply is the major concern for every electronic device .Since the

controller and other devices used are low power devices there is a need to step down the

voltage and as well as rectify the output to convert the output to a constant dc

Fig 3.1.Block Diagram of Power supply

3.1 Transformer:

Transformer is a device used to increment or decrement the input voltage given as

per the requirement. The transformers are classified into two types depending upon there

functionality

Step up transformer

Step down transformer

Here we use a step down transformer for stepping down the house hold ac power

supply i.e. the 230-240v power supply to 5 v .We use a 5-0-5 v center tapped step down

transformer.


3.2 Rectifier:

The output of the transformer is an ac and should be rectified to a constant dc for

this it is necessary to feed the output of the transformer to a rectifier. The rectifier is

employed to convert the alternating ac to a constant dc.

There are many rectifiers available in the market some of them are:-

Half wave rectifier

Full wave rectifier

Bridge rectifier

The rectification is done by using one or more diodes connected in series or parallel.

If only one diode is used then only first half cycle is rectified and it is termed as

half wave rectification and the rectifier used is termed as half wave rectifier. If two

diodes are employed in parallel then both positive and negative half cycles are rectified

and this is full wave rectification and the rectifier is termed as Full wave rectifier.

If the diodes are arranged in the form of bridge then it is termed as Bridge

rectifier, it acts as a full wave rectifier. These rectifiers are available in the market in the

form of integrated chips (I.Cs)

3.3 Voltage Regulator:

The voltage regulator is used for the voltage regulation purpose. We use IC 7805

voltage regulator. The IC number has a specific significance. The number 78 represents

the series while 05 represent the output voltage generated by the IC

3.4 Light Emitting Diode:

We employ a light emitting diode for testing the functionality of the power supply

circuit. LED’s are also employed in other areas for many purposes. The fallowing are the

advantages of using LED’s.

It helps us while troubleshooting the device i.e. when the device is

malfunctioning it would be easy to detect where the actual problem araised


LED employed with microcontroller verifies whether data is being

transmitted


4. MICROCONTROLLER (PIC 18F452)

The PIC 18f452 CMOS FLASH-based 8-bit microcontroller is upward

compatible with the PIC16C73B/74B/76/77, PIC16F873/874/876/877devices. It features

200 ns instruction execution, self programming, an ICD, 2 Comparators, 8 channels of 8-

bit Analog-to-Digital (A/D) converter, 2 capture/compare/PWM functions, a synchronous

serial port that can be configured as either 3-wire SPI or 2-wire I2C bus, a USART, and a

Parallel Slave Port.

4.1 Features:

Operating frequency -DC-40MHZ

Program memory(Bytes)- 32K

Program memory(instructions)-16384

Data memory(Bytes)-1536

Data EEPROM memory(Bytes)- 256

I/O ports-Ports A,B,C,D,E

Timers-4

Capture/Serial communications –2

Serial communications, Addressable USART

RESETS(and delays)- POR,BOR,RESET instruction, Stack full Stack

Underflow(PRWT,OST)

Instruction set -75 instructions

Packages-44 PLCC,40 pin Dip,44 pin TQFP


4.1.1 Special Features:

100,000 erase/write cycle Enhanced FLASH program memory typical

1,000,000 erase/write cycle Data EEPROM Memory

FLASH/Data EEPROM Retention: > 40 years

Self-reprogrammable under software control

Power-on Reset (POR), Power-up Timer (PWRT) and Oscillator Start-up Timer

(OST)

Watchdog Timer (WDT) with its own On-Chip RC Oscillator for reliable

operation

Programmable code protection

Power saving SLEEP mode

Selectable oscillator options including

Single supply 5V

Low power, high speed FLASH/EEPROM technology

Fully static design

Wide operating voltage range (2.0V to 5.5V)

Industrial and Extended temperature ranges

4.2 Description of Microcontroller (PIC 18f452):

4.2.1 Clock / instruction cycle:

Clock is microcontroller's main starter, and is obtained from an

external component called an "oscillator". If we want to compare a microcontroller with a

time clock, our "clock" would then be a ticking sound we hear from the time clock. In

that case, oscillator could be compared to a spring that is wound so time clock can run.

Also, force used to wind the time clock can be compared to an electrical supply.

Clock from the oscillator enters a microcontroller via OSC1 pin where internal

circuit of a microcontroller divides the clock into four even clocks Q1, Q2, Q3, and Q4


which do not overlap. These four clocks make up one instruction cycle (also called

machine cycle) during which one instruction is executed.

Execution of instruction starts by calling an instruction that is next in string.

Instruction is called from program memory on every Q1 and is written in instruction

register on Q4. Decoding and execution of instruction are done between the next Q1 and

Q4 cycles. On the following diagram we can see the relationship between instruction

cycle and clock of the oscillator (OSC1) as well as that of internal clocks Q1-Q4.

Program counter (PC) holds information about the address of the next instruction.

Fig 4.1 Pin Diagram of PIC Microcontroller 18F452


Pin Description

1 - MCLR/VPP

2 - RA0/AN0

3 - RA1/AN1

4 - RA2/AN2/VREF-

5 - RA3/AN3/VREF+

6 - RA4/T0CKI

7 - RA5/AN4/SS/LVDIN

8 - RE0/RD/AN5

9 - RE1/WR/AN6

10 - RE2/CS/AN7

11 - VDD

12 - VSS

13 - OSC1/CLKIN

14 - OSC2/CLKO/RA6

15 - RC0/T1OSO/T1CKI

16 - RC1/T1OSI/CCP2

17 - RC2/CCP1

18 - RC3/SCK/SCL

19 - RD0/PSP0

20 - RD1/PSP1

21 - RD2/PSP2

22 - RD3/PSP3

23 - RC4/SDI/SDA

24 - RC5/SDO

25 - RC6/TX/CK

26 - RC7/RX/DT

27 - RD4/PSP4

28 - RD5/PSP5


29 - RD6/PSP6

30 - RD7/PSP7

31 - VSS

32 - VDD

33 - RB0/INT0

34 - RB1/INT1

35 - RB2/INT2

36 - RB3/CCP2

37 - RB4

38 - RB5/PGM

39 - RB6/PGC

40 - RB7/PGD

4.3 Ports:

Term "port" refers to a group of pins on a microcontroller which can be accessed

simultaneously, or on which we can set the desired combination of zeros and ones, or read from

them an existing status. Physically, port is a register inside a microcontroller which is connected

by wires to the pins of a microcontroller. Ports represent physical connection of Central

Processing Unit with an outside world. Microcontroller uses them in order to monitor or control

other components or devices. Due to functionality, some pins have twofold roles like

PA4/TOCKI for instance, which is in the same time the fourth bit of port A and an external input

for free-run counter. Selection of one of these two pin functions is done in one of the

configuration registers. An illustration of this is the fifth bit T0CS in OPTION register. By

selecting one of the functions the other one is disabled.

All port pins can be designated as input or output, according to the needs of a device

that's being developed. In order to define a pin as input or output pin, the right combination of

zeros and ones must be written in TRIS register. If the appropriate bit of TRIS register contains

logical "1", then that pin is an input pin, and if the opposite is true, it's an output pin. Every port

has its proper TRIS register. Thus, port A has TRISA, and port B has TRISB. Pin direction can be

changed during the course of work which is particularly fitting for one-line communication where


data flow constantly changes direction. PORTA and PORTB state registers are located in bank 0,

while TRISA and TRISB pin direction registers are located in bank 1.

4.3.1 Port and Tris:

Register defines the corresponding port pin as input, and resetting a bit in TRIS

register PORT has adjoined 8 pins. The appropriate register for data direction is TRIS.

Setting a bit in TRIS defines the corresponding port pin as output.

4.4 Memory Organization:

PIC18F452 has two separate memory blocks, one for data and the other for the

program. EEPROM memory with GPR and SFR registers in RAM memory make up data

block, while FLASH memory makes up the program block.

A) Program Memory:

Program memory has been carried out in FLASH technology which makes it the

possible to program a microcontroller many times before it's installed into a device and

even after its installment if eventual changes in program or process parameters should

occur. The size of program memory is1024 locations w.ith 14 bits width where locations

zero and four are reserved for reset and interrupt vector.

B) Data Memory:

Data memory consists of the EEPROM and RAM memories. EEPROM memory

consists of 256 eight bit locations whose content are not lost during loosing of power

supply. EEPROM is not directly addressable, but is accessed indirectly through EEADR

and EEDATA registers. As EEPROM memory usually serves for storing important

parameters (for example, of a given temperature in temperature regulators), there is a

strict procedure for writing in EEPROM which must be followed in order to avoid

accidental writing. RAM memory for data occupies space on a memory map from

location 0x0C to 0x4F which comes to 68 locations. Locations of RAM memory are also


called GPR registers which is an abbreviation for General Purpose Registers. GPR

registers can be accessed regardless of which bank is selected at the moment.

4.5 Memory Banks:

Beside this 'length' division to the SFR and the GPR registers, memory map is

also divided in 'width' (see preceding map) to two areas called 'banks'. Selecting one of

the banks is done through the RP0 bit in the STATUS register.

4.6 Program Counter:

Program counter is a 13-bit register that contains the address of the instruction

being executed. It is physically carried out as a combination of a 5-bit register PCLATH

for the five higher bits of the address, and the 8-bit register PCL for the lower 8 bits.

4.7 Stack:

PIC18F452 has a 13-bit stack with 8 levels, or in other words, a group of 8

memory locations, 13 bits wide, with special purpose. Its basic role is to keep the value of

program counter after a jump from the main program to an address of a subprogram. In

order for a program to know how to go back to the point where it started from, it has to

return the value of a program counter from a stack.

4.8 Interrupts:

Interrupts are a mechanism of a microcontroller which enables it to respond to

some events at the moment they occur, regardless of what microcontroller is doing at the

time. This is a very important part, because it provides connection between a

microcontroller and environment which surrounds it. Generally, each interrupt changes

the program flow, interrupts it and after executing an interrupt subprogram (interrupt

routine) it continues from that same point on.


Control register of an interrupt is called INTCON and can be accessed regardless

of the bank selected. Its role is to allow or disallowed interrupts, and in case they are not

allowed, it registers single interrupt requests through its own bits.

A) IE (Interrupt Enable):

A single microcontroller can serve several devices. In the interrupt method,

whenever any device needs its service, the device notifies the microcontroller by sending

it can interrupt signal. . The program associated with the interrupt is called the interrupt

service routine (ISR). The advantageous of interrupts is that the microcontroller can

serve many devices based on the priority assigned to it. There are six interrupts in the

micro controller

1. Reset.

2. Two interrupts are set aside for the timers.

3. Two interrupts are set aside for hardware external hardware interrupts.

4. Serial Communications has a single interrupt (receive and transfer).

.

Fig 4.2 Format of Interrupt Enable (IE)

EA disable all interrupts. If EA = 0, now interrupt is acknowledged. If EA = 1, each

interrupt source is individually enabled or disabled by setting or clearing its

enable a lap bit.

---- Not implemented, reserved for future use.

ET2 enables or disables timer 2 overflow or capturer interrupt.

ES enables or disables the serial port interrupt.

ET1 enables or disables timer 1 overflow interrupt.

EX1 enables or disables external interrupt 1.

ET0 enables or disables timer 0 overflow interrupt.


EX0 enables or disables external interrupt 0.

B) IP (Interrupt Priority):

The Interrupt Priority SFR is used to specify the relative priority of each

interrupt. On the 8051, an interrupt may either be of low (0) priority or high (1) priority.

An interrupt may only interrupt interrupts of lower priority.

Fig 4.3 Format of Interrupt Priority (IP)

--- IP.7 Reserved

--- IP.6 Reserved

PT2 IP.5 Timer2 Interrupt Priority bit (for 8052 only)

PS IP.4 Serial Port Interrupt Priority Bit

PT0 IP.1 Timer0 Interrupt Priority Bit

PX0 IP.0 External Interrupt Priority Bit

4.9 PSW (Program Status Word):

The Program Status Word is used to store a number of important bits that are set

and cleared by microcontroller instructions.

.

Fig 4.4 Format of Program Status Word (PSW)

CY Carry-flag.

AC Auxiliary carry-flag.

---- Available to the user for general-purpose.


RS1 register bank selector bit 1.

OV overflow flag.

---- User definable bit.

P Parity flag. It is used in the error detection by adding a bit.

4.10 TIMERS:

The "timer” or "counter "function is selected by control bits C/T in the special

function register TMOD. These two timer/counters have for operating modes, which are

selected by bit-pairs (M1/M0) in TMOD. Modes 0, 1, and 2 are the same for both

timers/counters. Mode 3 is different.

These two SFRs, taken together, represent timer 0. Their exact behavior depends

on how the timer is configured in the TMOD SFR; however, these timers always count

up. What is configurable is how and when they increment in value.

Fig 4.5 Format of Timer Mode Register (TMOD)

GATE: When set, start and stop of timer by hardware

When reset, start and stop of timer by software

C/T: Cleared for timer operation

Set for counter operation

Table 4.1 Modes of TMOD

M1 M0 MODE OPERATING MODE

0 0 0 13-bit timer mode

0 1 1 16-bit timer mode

1 0 2 8-bit auto reload mode


1 1 3 Split timer mode

4.10.1 Timer 1:

These two SFRs, taken together, represent timer 1. Their exact behavior depends

on how the timer is configured in the TMOD SFR; however, these timers always count

up. What is configurable is how and when they increment in value.

Address =88H.

Bit addressable.

Fig 4.6 Format of Timer Control Register (TCON)

TF: Timer overflow flag: Set by hardware when the timer/counter overflows. It is

cleared by hardware, as the processor vectors to the interrupt service routine.

TR: timer run control bit: Set or cleared by software to turn timer or counter on/off.

IE: set by CPU when the external interrupt edge (H-to-L transition) is detected. It is

cleared by CPU when the interrupt is processed.

IT: set/cleared by software to specify falling edge/low-level triggered external

interrupt.

4.10.2 Free-run timer TMR0:

It is an 8-bit register inside a microcontroller that works independently of the

program. On every fourth clock of the oscillator it increments its value until it reaches the

maximum (255), and then it starts counting over again from zero. As we know the exact


timing between each two increments of the timer contents, timer can be used for

measuring time which is very useful with some devices.

4.10.3 TMOD (Timer Mode):

The Timer Mode SFR is used to configure the mode of operation of each of the

two timers. Using this SFR your program may configure each timer to be a 16-bit timer,

an 8-bit auto reload timer, a 13-bit timer, or two separate timers. Additionally, you may

configure the timers to only count when an external pin is activated or to count "events"

that are indicated on an external pin.

4.11 SCON (Serial Control):

The Serial Control SFR is used to configure the behavior of the 8051's on-board

serial port. This SFR controls the baud rate of the serial port, whether the serial port is

activated to receive data, and also contains flags that are set when a byte is successfully

sent or received.

Bit addressable.

8H

Fig 4.7 Format of Serial Control Register (SCON)

REN set or cleared by software to enable or disable reception.

TB 8 not widely used.

RB 8 not widely used.

TI transmits interrupt flag. Set by hardware at the beginning of the stop bit in mode

1. It must be cleared by software.

RI received interrupts flag. Set by hardware halfway through the stop bit time in

mode 1. It must be cleared by software.


Table 4.2 Modes of SCON

SM0 SM1 Mode Of Operation

0 0 Synchronous mode

0 1 8-bit data, 1 start bit, 1 stop bit, variable

baud rate

1 0 9- bit data, 1 start bit, 1 stop bit, fixed

baud rate

1 1 9- bit data, 1 start bit, 1 stop bit, variable

baud rate

4.12 Applications:

PIC18F452 perfectly fits many uses, from automotive industries and controlling

home appliances to industrial instruments, remote sensors, electrical door locks and

safety devices. It is also ideal for smart cards as well as for battery supplied devices

because of its low consumption.

EEPROM memory makes it easier to apply microcontrollers to devices where

permanent storage of various parameters is needed (codes for transmitters, motor speed,

receiver frequencies, etc.). Low cost, low consumption, easy handling and flexibility

make PIC18F452 applicable even in areas where microcontrollers had not previously

been considered (example: timer functions, interface replacement in larger systems,

coprocessor applications, etc.).

In System Programmability of this chip (along with using only two pins in data

transfer) makes possible the flexibility of a product, after assembling and testing have


been completed. This capability can be used to create assembly-line production, to store

calibration data available only after final testing, or it can be used to improve programs

on finished products.

5. GLOBAL POSITIONING SYSTEM

5.1 Introduction:

The Global Positioning System (GPS) is a burgeoning technology, which

provides unequalled accuracy and flexibility of positioning for navigation, surveying and

GIS data capture. The GPS NAVSTAR (Navigation Satellite timing and Ranging Global

Positioning System) is a satellite-based navigation, timing and positioning system. The

GPS provides continuous three-dimensional positioning 24 hrs a day throughout the

world. The technology seems to be beneficiary to the GPS user community in terms of

obtaining accurate data up to about100 meters for navigation, meter-level for mapping,

and down to millimeter level for geodetic positioning. The GPS technology has

tremendous amount of applications in GIS data collection, surveying, and mapping.

The Global Positioning System (GPS) is a U.S. space-based radio navigation

system that provides reliable positioning, navigation, and timing services to civilian users

on a continuous worldwide basis -- freely available to all. For anyone with a GPS

receiver, the system will provide location with time. GPS provides accurate location and

time information for an unlimited number of people in all weather, day and night,

anywhere in the world.

The Global Positioning System (GPS) is a satellite-based navigation system made

up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. GPS

was originally intended for military applications, but in the 1980s, the government made


the system available for civilian use. 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.

The GPS is made up of three parts: satellites orbiting the Earth; control and

monitoring stations on Earth; and the GPS receivers owned by users. GPS satellites

broadcast signals from space that are picked up and identified by GPS receivers. Each

GPS receiver then provides three-dimensional location (latitude, longitude, and altitude)

plus the time.

5.2 Geo positioning -- Basic Concepts:

By positioning we can understand the determination of stationary or moving

objects. These can be determined as follows:

1. In relation to a well-defined coordinate system, usually by three coordinate values

and

2. In relation to other point, taking one point as the origin of a local coordinate

system.

The first mode of positioning is known as point positioning, the second as relative

positioning. If the object to be positioned is stationary, we can term it as static

positioning. When the object is moving, we call it kinematics positioning. Usually, the

static positioning is used in surveying and the kinematics position in navigation.

5.2.1 GPS Basic Facts:

The GPS uses satellites and computers to compute positions anywhere on earth.

The GPS is based on satellite ranging. That means the position on the earth is determined

by measuring the distance from a group of satellites in space. The basic principles behind

GPS are really simple, even though the system employs some of the high-techest

equipment ever developed. In order to understand GPS basics, the system can be

categorized into 5 Logical steps.


They are listed below:

1. Triangulation from the satellite is the basis of the system.

2. To triangulate, the GPS measures the distance using the travel time of the radio

message.

3. To measure travel time, the GPS need a very accurate clock.

4. Once the distance to a satellite is known, then we need to know where the satellite

is in space.

5. As the GPS signal travels through the ionosphere and the earth's atmosphere, the

signal is delayed.

6. To compute a position in the three dimensions, we need to have four satellite

measurements. The GPS uses a trigonometric approach to calculate the positions,

The GPS satellites are so high up that their orbits are very predictable and each of

the satellites is equipped with a very accurate atomic clock.

5.3 Components of a GPS:

The GPS is divided into three major components


Fig 5.1 different components of GPS

A) The Control Segment:

The DOD monitoring stations track all GPS signals for use in controlling the

satellites and predicting their orbits. Meteorological data also are collected at the

monitoring stations, permitting the most accurate evaluation of tropospheric delays of

GPS signals. Satellite tracking data from the monitoring stations are transmitted to the

master control station for processing. This processing involves the computation of

satellite ephemerides and satellite clock corrections. The master station controls orbital

corrections, when any satellite strays too far from its assigned position, and necessary

repositioning to compensate for unhealthy (not fully functioning) satellites.

B) The Space Segment:


The Space Segment consists of the Constellation of NAVASTAR earth orbiting

satellites. The current Defense Department plan calls for a full constellation of 24 Block

II satellites (21 operational and 3 in-orbit spares). The satellites are arrayed in 6 orbital

planes, inclined 55 degrees to the equator. They orbit at altitudes of about 12000, miles

each, with orbital periods of 12 sidereal hours (i.e., determined by or from the stars), or

approximately one half of the earth's periods, approximately 12 hours of 3-D position

fixes. The next block of satellites is called Block IIR, and they will provide improved

reliability and have a capacity of ranging between satellites, which will increase the

orbital accuracy. Each satellite contains four precise atomic clocks (Rubidium and

Cesium standards) and has a microprocessor on board for limited self-monitoring and

data processing. The satellites are equipped with thrusters which can be used to maintain

or modify their orbits.

.

C) The User Segment:

The user segment is a total user and supplier community, both civilian and

military. The User Segment consists of all earth-based GPS receivers. Receivers vary

greatly in size and complexity, though the basic design is rather simple. The typical

receiver is composed of an antenna and preamplifier, radio signal microprocessor, control

and display device, data recording unit, and power supply. The GPS receiver decodes the

timing signals from the 'visible' satellites (four or more) and, having calculated their

distances, computes its own latitude, longitude, elevation, and time. This is a continuous

process and generally the position is updated on a second-by-second basis, output to the

receiver display device and, if the receiver display device and, if the receiver provides

data capture capabilities, stored by the receiver-logging unit.

5.4 How it works:

GPS satellites circle 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.

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, bearing, track, trip distance, distance to destination, sunrise

and sunset time and more.

Fig 5.2 G.P.S receiver communicating with the satellite and sending information

through the wireless mobile phone

5.5 GPS Radio Signals:

GPS satellites transmit two types of radio signals: C/A-code and P-code. Briefly,

here are the uses and differences of these two types of signals.

A) Coarse Acquisition (C/A-code):


Coarse Acquisition (C/A-code) is the type of signal that consumer GPS units

receive. C/A-code is sent on the L1 band at a frequency of 1575.42 MHz C/A broadcasts

are known as the Standard Positioning Service (SPS). C/A-code is less accurate than P-

code.

The advantage of C/A-code is that it’s quicker to use for acquiring satellites and

getting an initial position fix. Some military P-code receivers first track on the C/A-code

and then switch over to P-code.

B) Precision (P-code):

P-code provides highly precise location information. P-code is difficult to jam and

spoof. The U.S. military is the primary user of P-code transmissions, and it uses an

encrypted form of the data (Y-code) so only special receivers can access the information.

The P-code signal is broadcast on the L2 band at 1227.6 MHz P-code broadcasts are

known as the Precise Positioning Service (PPS).

5.6 Sources of GPS Signal Errors:

Factors that can degrade the GPS signal and thus affect accuracy include the following:

Ionosphere and troposphere delays — the satellite signal slows as it passes

through the atmosphere. The GPS system uses a built-in model that calculates an

average amount of delay to partially correct for this type of error.

Signal multipath — this occurs when the GPS signal is reflected off objects such

as tall buildings or large rock surfaces before it reaches the receiver. This

increases the travel time of the signal, thereby causing errors.


Receiver clock errors — a receiver's built-in clock is not as accurate as the atomic

clocks onboard the GPS satellites. Therefore, it may have very slight timing

errors.

Number of satellites visible — the more satellites a GPS receiver can "see," the

better the accuracy. Buildings, terrain, electronic interference, or sometimes even

dense foliage can block signal reception, causing position errors or possibly no

position reading at all. GPS units typically will not work indoors, underwater or

underground.

Fig 5.3 GPS modem device

5.7 Features:

Low cost

Compact (74x74x19mm)

12 Channel Receiver

Built-in Antenna


Standard NMEA protocol USB or Serial

5.8 Receiver types:

A) Mapping/resource models:

These portable receivers collect location points and line and area data that can be

input into a Geographic Information System (GIS). They are more precise than consumer

models, can store more data, and are much more expensive.

B) Survey models:

These are used mostly for surveying land, where you may need accuracy down to

the centimeter for legal or practical purposes. These units are extremely precise and store

a large amount of data. They tend to be large, complex to use, and very expensive.

C) Commercial transportation models:

These GPS receivers, not designed to be handheld, are installed in aircraft, ships,

boats, trucks, and cars. They provide navigation information appropriate to the mode of

transportation. These receivers may be part of an Automated Position Reporting System

(APRS) that sends the vehicle’s location to a monitoring facility

5.9 Information from GPS Receivers:

GPS receivers provide our location and other useful information:

a. Time: A GPS receiver receives time information from atomic clocks, so it’s much

more accurate than your wristwatch.

b. Location: GPS provides your location in three dimensions. Latitude (x

coordinate)

Longitude (y coordinate) and Elevation.


c. Speed: When we are moving, a GPS receiver displays your speed.

d. Direction of travel: A GPS receiver can display our direction of travel if we are

moving. If we are stationary, the unit can’t use satellite signals to determine

which direction we are facing.

e. Stored locations: we can store locations where we’ve been or want to go with a

GPS receiver. These location positions are waypoints. Waypoints are important

because a GPS unit can supply us with directions and information on how to get

to a waypoint. A collection of waypoints that plots a course of travel is a route,

which can also be stored. GPS receivers also store tracks (which are like an

electronic collection of breadcrumb trails that show where we’re been).

f. Cumulative data: A GPS receiver can also keep track of information such as the

total distance traveled, average speed, maximum speed, minimum speed, elapsed

time, and time to arrival at a specified location.

5.10 GPS Positioning Types:

There are two types of GPS positioning system

A) Absolute positioning:

The mode of positioning relies upon a single receiver station. It is also referred to

as 'stand-alone' GPS, because, unlike differential positioning, ranging is carried out

strictly between the satellite and the receiver station, not on a ground-based reference

station that assists with the computation of error corrections. As a result, the positions

derived in absolute mode are subject to the unmitigated errors inherent in satellite

positioning. Overall accuracy of absolute positioning is considered to be no greater than

50 meters at best by Ackroyd and Lorimer and to be + 100 meter accuracy by the U.S.

B) Differential Positioning:


Relative or Differential GPS carries the triangulation principles one step further,

with a second receiver at a known reference point. To further facilitate determination of a

point's position, relative to the known earth surface point, this configuration demands

collection of an error-correcting message from the reference receiver.

Differential-mode positioning relies upon an established control point. The reference

station is placed on the control point, a triangulated position, the control point coordinate.

This allows for a correction factor to be calculated and applied to other roving GPS units

used in the same area and in the same time series. This error correction allows for a

considerable amount of error of error to be negated, potentially as much as 90 percent.

Fig 5.4 GPS setup

5.11 Two Common Sources of More Accurate Location Data:

Differential GPS (DGPS)

Wide Area Augmentation System (WAAS)

A) Differential GPS:


Surveying and other work that demands a high level of precision use Differential

GPS (DGPS) to increase the position accuracy of a GPS receiver. A stationary receiver

measures GPS timing errors and broadcasts correction information to other GPS units

that are capable of receiving the DGPS signals. Consumer GPS receivers that support

DGPS require a separate beacon receiver that connects to the GPS unit. Consumers can

receive DGPS signals from free or commercial sources.

B) WAAS:

Wide Area Augmentation System (WAAS) combines satellites and ground

stations for position accuracy of better than three meters. Vertical accuracy is also

improved to three to seven meters. WAAS is only available in North America. Other

governments are establishing similar systems that use the same format radio signals such

as

European Euro Geostationary Navigation Overlay Service (EGNOS)

Japanese Multi-Functional Satellite Augmentation System (MSAS)

5.12 GPS Accuracy:

Table 5.1 describing of GPS accuracy:

GPS Mode Distance in Feet Distance in Meters

GPS without SA 49 15

GPS with DGPS 10–16 3–5

GPS with WAAS 10 3

5.13 Need of Reference Station:

For any level, except autonomous (which can have a large amount of error in it),

we must have a reference receiver, which is stationary, and a rover.


The coordinates of this station must be known before we can begin using GPS on

any of our machines. First a proper site for the reference station is to be selected, and then

a GPS survey is performed to obtain the known coordinates. Once it is installed, the GPS

reference station can perform two functions simultaneously.

Receive data from the satellites

Broadcast GPS data to the rovers in the mine

5.13.1 Selecting the Reference Station:

Proximity to our Working Areas: This is both a GPS issue and a radio issue.

Remember, RTK is generally limited to about 10-15 Km (6-9 miles).

Absence of RF Interference: Try to place the reference station away from sources

of radio interference, which arise from radio towers, transmitters, television

Minimal Sources of Multipath: Multipath at our reference site can cause

inaccurate answers or interfere with our rover's ability to initialize.

Continuous AC / DC Power Source

Stable Documentation: One should have a stable survey monument or other

similarly well-defined physical point at the reference station

Stable Antennae Mount Not only the monument should be stable, but also the

GPS antennae itself should be secure and stable to minimize the movement.

5.13.2 Reference Station Equipment:

GPS receiver

GPS antenna

Radio and antenna, Power supply, & Cables

1) Radios:

We have seen that each GPS rover must receive information from the reference

station to achieve accurate positions. To maintain constant communication between our

reference station and rover, we need


Radio

Radio Antenna

Cables

The radios are cabled directly into the GPS receiver. Power may be provided to

the radio through the GPS receiver. At the reference site, the GPS data is broadcast

through the radio. At the rover site, the reference GPS data is received by the radio and

are routed into the rover receiver, where it is processed together with rover's the GPS

data.

2) Repeater Radios:

If, for any reason, the reference station transmission cannot reach our rovers, then

we must use one or more repeaters. A repeater relays the data from our reference or

another repeater. The maximum number of repeaters we can use depends on our type of

radio. Repeaters differ from our reference and rover radios in two important ways: they

must have their own source of power, and they can be moved as the needs change. Radios

draw very low power, but they require uninterrupted power. Because repeaters may need

to be moved to accommodate our needs, batteries or compact solar power units are used.

Frequency and Bandwidth: Most radios used in GPS fall within one of the

following frequency ranges:

150-174 MHz (VHF)

406-512 MHz (UHF)

902-928 MHz (spread spectrum)

The lower-frequency radios (150-174 MHZ) tend to have more power, due to

design and legal issues (not Physics), However, the bandwidth, which determines the

amount of data we can transmit, is narrower in these lower ranges (also due to design, not

physics). In the nominal 450 MHz and 900 MHz ranges, the bandwidth is wider.


3) Radio Range:

To guarantee steady, uninterrupted transmission over the radio, one should be

aware of some of the factors that affect the radio's effective range.

Antenna Height: raising the radio antenna is the easiest and most effective way to

increase range.

Antenna design: radiating patterns vary, depending on the antenna design.

Cable length and type: radio signals suffer loss in cables, so keep the length to a

minimum. If we must use long cables, use low-loss cables.

Output power: doubling output power does not double our effective range.

Obstructions: Buildings, walls and even the machines can block or interrupt radio

transmission.

Grounding: The radio antenna may be a target for lightning.

5.14 GPS Has Internal And External Memories:

5.14.1 Internal Memory:

A receiver’s internal memory holds such data as waypoints, track logs, routes, and

up loadable digital maps (if the model supports them). The more memory the receiver

has, the more data we can store in it. All the data that’s been stored in the GPS receiver is

retained when the device is turned off.GPS receivers have different amounts of memory.

Unlike personal computers, we can’t add memory chips to a GPS unit to expand its

internal memory.

5.14.2 External Storage:

Some GPS receivers aren’t limited to internal memory for storage, using support

memory cards that can be plugged into the receiver to store data. External memory can be

either Manufacturer proprietary data cards or Generic (and less expensive) storage, such

as

Multi Media Card (MMC)


Secure Digital (SD)

5.15 NMEA Format:

GPS gives the output in NMEA format which means national marine electronics

association. This GPS output contains six to seven lines of data out of that only two lines

are sufficient for us to trace the complete path journey of any vehicle or moving objects.

Those two lines are GPGGA which gives time, position and fix type data and GPRMC

(Recommended minimum sentence) which gives time, date, position, course and speed

data.

GPGGA: $GPGGA,161229.487,3723.2475,N,12158.3416,E,1,07,1.0,9.0,M, , , ,0000*18

GPRMC: $GPRMC,161229.487,A,3723.2475,N,12158.3416,E,0.13,309.62,120598, ,*10

NMEA output messages are:

Option Description

GGA Time, position and fix type data

RMC Time, data, position, course and speed data

In this format every line starts with $ symbol and ends with * indicating starting

and ending of lines, after this 161229 indicates the time at that instant 16hrs 12min 29

sec, next latitude of 37 degrees 23.2475’ N, longitude of 121 degrees 58.3416’E. ‘A’

indicates the active data.*18 indicate the checksum data. By using longitudes and

latitudes we can locate the position of a particular location. This NMEA format is

converted using ccs compiler and opened on Google Earth computerized map then we

have the complete path journey of any vehicle or moving objects.


5.16 GPRMC Data Format:

RMC (Recommended Minimum Navigation Information):

1 2 3 4 5 6 7 8 9 10 11 12

| | | | | | | | | | | |

$--RMC,hhmmss.ss,A,llll.ll,a,yyyyy.yy,a,x.x,x.x,xxxx,x.x,a*hh

1 Time (UTC)

2 Status, V = Navigation receiver warning

3 Latitude

4 N or S

5 Longitude

6 E or W

7 Speed over ground, knots

8 Track made good, degrees true

9 Date, dd-mm-yy

10 Magnetic Variation, degrees


11 E or W

12 Checksum

5.17 GPS Applications:

One of most significant and unique features of the Global Positioning Systems is

the fact that the positioning signal is available to users in any position worldwide at any

time. With a fully operational GPS system, it can be generated to a large community of

likely to grow as there are multiple applications, ranging from surveying, mapping,and

navigation to GIS data capture.GPS will soon be a part of the overall utility oftechnology.

There are countless GPs applications, a few important ones are covered in the following

passage.

Science:

Archaeology

Environmental

Transportation:

Aviation

Space

Military:

Intelligence and Target Location

Navigation

Weapon aiming and Guidance

Industry:

Mapping


Public safety

Surveying

Telecommunications

6. MULTIMEDIA CARD

6.1 Introduction:

The Multimedia Card (MMC) is a flash memory card standard. A memory card or

flash memory card is solid-state electronic flash memory data storage device capable of

storing digital contents.

The MMC is the smallest removable flash memory designed specifically for

digital applications, such as MP3 music players, digital video cameras, mobile phones,

voice recorder, video game consoles, and other electronics. The Multi Media Card has a

wide variety of uses in some of the most exciting products on the market today.

A MMC is used as storage media for a portable device, in a form that can easily

be removed for access by a PC. For example, a digital camera would use an MMC for

storing image files.

MMCs are currently available in sizes up to and including 32 GB. They are used

in almost every context in which memory cards are used, like cellular phones, digital

audio players and digital cameras. Since the introduction of Secure Digital card few

companies build MMC slots into their devices (an exception is some mobile devices like

the Nokia 9300 communicator, where the smaller size of the MMC is a benefit), but the

slightly thinner, pin-compatible MMCs can be used in almost any device that supports

SD cards if the software/firmware on the devices support them.

6.2Types of MMC:

A) An RS-MMC with adapter:


The RS-MMC card is approximately half the size of the full Multimedia Card.

Having the same width and thickness; RS-MMC measures 18mm from top to bottom

instead of 32mm. With capacities of 1GB as of 2005, RS-MMC cards can be pushed into

an adapter and plugged into full-size MMC slots.

B) Dual-Voltage Multimedia Card (DV-MMC):

One of the first substantial changes in MMC was the introduction of dual-voltage

cards that support operations at 1.8 V in addition to 3.3 V. Running at lower voltages

reduces the card's power consumption, which is important in mobile devices. However,

simple dual-voltage parts quickly went out of production in favor of MMC plus and

MMC mobile, which offer additional capabilities on top of dual-voltage support.

C) MMC micro:

MMC micro is a micro-size version of MMC. With dimensions of 14 mm ×

12 mm × 1.1 mm, it is even smaller and thinner than RS-MMC. Like MMC mobile,

MMC micro supports dual voltage, is backward compatible with MMC, and can be used

in full-size MMC and SD slots with a mechanical adapter. MMC micro cards support the

high-speed and 4 bit bus features of the 4.x spec, but not the 8-bit bus, due to the absence

of the extra pins. An MMC micro card appears very similar to micro SD but the two

formats are not physically compatible and have incompatible pin outs.

6.3 Design and Implementation:

SD cards are based on the older Multimedia Card (MMC) format, but have a

number of differences:

The SD card is asymmetrically shaped in order not to be inserted upside down,

while an MMC would go in most of the way but not make contact if inverted.


Fig 6.1 SD card, mini SD card, and micro SD card from top to bottom.

Most SD cards are physically thicker than MMCs. SD cards generally measure

32 mm × 24 mm × 2.1 mm, but as with MMCs can be as thin as 1.4 mm if they

lack a write-protect switch; such cards, called "Thin SD", are described in the SD

specification, but they are non-existent or rare in the market as devices that would

require a thinner card are usually utilizing the smaller (and thinner) versions of

SD: miniSD or microSD.

The card's electrical contacts are recessed beneath the surface of the card,

protecting them from contact with a user's fingers.

SD cards typically have transfer rates in the range of 10-20 MB/s, but this number

is subject to change, due to recent improvements to the MMC standard.


Devices with SD slots can use the thinner MMCs, but standard SD cards will not

fit into the thinner MMC slots. MiniSD cards can be used directly in SD slots with

a simple passive adapter, since the cards differ in size and shape but not electrical

interface. With an active electronic adapter, SD cards can be used in Compact

Flash or PC card slots. Some SD cards include a USB connector for compatibility

with desktop and laptop computers, and card readers allow SD cards to be

accessed via connectivity ports such as USB, FireWire, and the parallel printer

port. SD cards can also be accessed via a floppy disk drive with a Flash Path

adapter

6.4 Working of MMC:

MMC (Multi Media Card) is a device which can be used to store the data within it in

the form of files.

MMC card can be interfaced with Microcontroller using SPI (Serial Peripheral

Interface) protocol.

We are using this MMC card to store the logged GPS data.

The logged GPS data can be copied onto a computer and then can be displayed on

Google Earth computerized map

We are using 64MB MMC card.

6.5 SD/MMC Mini Board:

Our new SD/MMC Mini Board is a great way to interface to a standard SD or

MMC memory card. This board features a standard SD/MMC connector for easy


connection of your memory card. Data can be easily downloaded or read from the card

using standard SD or SPI communication.

Fig 6.2 Mini board of MMC


This board incorporates standard TTL connectors for easy connection. A Card

Detect signal and LED, together with a Red Power LED. The connector is a high-quality

AVX card connector, for reliable and long-life performance. This board can be easily

configured to work with our MP3 Mini-Board, as a simple MP3 Player. Ideal also as a

data storage board for real-time data and program storage.

The new SD/MMC Mini Board is ideal for a wide range of data storage and

programming applications. The board connects easily using a standard SPI interface and

programs can be quickly developed to utilize standard memory cards.

6.6 Features of Mini Board:

It can be used with SD and MMC Cards.

High-Quality AVX Card Socket.

LED Indication for Card Presence.

Standard Communications interfaces for Data Read and Write.

Easily Connects to most microcontrollers.

Ideal for use as an easily removable Data-Storage Device.

Board Dimensions: 45 x 55 mm.

6.7 Features of MMC:

Universal low cost data storage and communication media.

The MMC communication is based on 7 pin serial bus

Operate in a low voltage range of 2.0 to 3.6V


Targeted for portable and stationary applications

Noted for high date rate of 52Mbps

Secure Versions of card is available.

MMC uses flash memory for read/write application or ROM chip for static

application

6.8 Secure Versions:

Two secure versions of the Multimedia Card are offered. Secure MMC for

Content Protection is used for copyrighted material. It contains encrypted content in

readable flash memory and licensing information in a hardware-protected, tamper proof

part of the card. Secure MMC for M-Commerce is a high-level security card for e-

commerce.

6.9 MMC and SD Cards:

Multimedia Cards and SD Memory Cards share the same footprint, but MMCs are

thinner and have only seven pins compared to nine. MMC cards can be read in SD Card

readers, but SD Cards cannot be read in readers designed for MMC only.


Fig 6.3 Multimedia card

6.10 Advantages:

Universal low cost data storage and communication media.

High performance at a low cost price.

Low power consumption.

High data through at a memory card interface.

MMC Communication is based on an advanced 7-pin serial bus designed to

operate in a low voltage range.

Reduced-Size Multimedia Card (RS-MMC):

6.11 Applications of MMC:

1) It is used for digital applications such as MP3 music players, digital video cameras,

mobile phones, voice recorders.

2) The RS-MMC is aimed primarily at mobile phone and digital camera


7. SERIAL AND WIRELESS COMMUNICATION

7.1 Serial Communication:

Serial communication is used for transferring data between two systems located at

distances of hundreds of feet to millions of miles apart.

Serial data communication uses two methods, a synchronous and asynchronous.

The synchronous method transfers a block of data at a time while the synchronous

transfers a single byte at a time. For this reason, there are special IC chips made by many

manufacturers for serial data communications. These chips are commonly referred to as

UART and USART.

7.1.1 ASYNCHRONOUS SERIAL COMMUNICATION:

In the asynchronous method, each character is placed in between start and stop

bits. This is the called framing. In data framing for asynchronous communications, the

data, such as ASCII characters, are packed in between a start bit and a stop bits. The start

bit is always one-bit but the stop bit can be one or two bits. If the transmitter and receiver


are using different speeds, stop bit will not be received at the expected time problem is

called framing error. The start bit is always a 0 and the stop bit is 1.

A) PARITY BIT:

In some systems in order to maintain data integrity, the parity bit of the character

byte is included in the data frame. The parity bit is odd or even. In case of an odd parity

bit the number of data bits of a book of including the parity bit, is even.

B) DATA TRANSFER RATE:

The rate of data transfer in serial data communication is stated in bps. Another

widely used terminology for bps is baud rate. Baud rate is defined as the number of

signal changes per second.

7.2 RS232 STANDARDS:

Two allow compatibility among the data communication equipment made by

various manufacturers; an interfacing standard called RS232, was set by the electronics

industries association (EIA) in 1960. RS 232 is the standard defined for the connection

of "Data Terminal Equipment" (DTE) to "Data Communications Equipment" (DCE).

DTE is a generic term for an item which forms part of the "information

processing" portions of a system. Examples are: computer, printer, and terminal. DCE is

a device, which provides an interface between a DTE and a communications link.

In RS 232, a 1 is represented by -3 to -25V which is called Mark, while a 0 bit is

+ 3 to + 25V which is called Space. To connect any RS 232 to a µc system, voltage

converters such as Max 232are used. Max 232 IC chips are commonly referred to as line


drivers.8.3. MAX 232. The RS 232 is not compatible with micro controllers, so a line

driver converts the RS 232's signals to TTL voltage levels.

7.3 Wireless Communication:

7.3.1 Introduction:

Radio frequency (RF) transmitters are widely used in radio frequency

communications systems. With the increasing availability of efficient, low cost

electronic.

The transmitting baseband signal is subjected to a predetermined signal process,

input to a modulator, which modulates a carrier wave signal. The modulated carrier wave

signal is converted into a radio frequency by a transmitting radio-frequency circuit and

amplified to a predetermined transmitting power, and transmitted to the base station from

the antenna via the duplexer. Communication systems are known to support wireless and

wire lined communications between wireless and/or wire lined communication devices.

Such communication systems range from national and/or international cellular telephone

systems to the Internet to point-to-point in-home wireless networks. Depending on the

type of wireless communication system, a wireless communication device, such as a

cellular telephone, two-way radio, personal digital assistant (PDA), personal computer

(PC), laptop computer, home entertainment equipment, etc., communicates directly or

indirectly with other wireless communication devices.

7.3.2 Transmitter in RF Transceiver:

The base stations and subscriber units include radio frequency transmitters and

RF receivers, together they're called "RF transceivers." RF transceivers service the

wireless links between the base stations and subscriber units.

The RF transmitter receives a base band signal from a base band processor,

converts the base band signal to an RF signal, and couples the RF signal to an antenna for

transmission. In most RF transmitters, the base band signal is first converted to an

intermediate frequency (IF) signal and then the IF signal is converted to the RF signal.

http://www.electronics-manufacturers.com/info/





The data modulation stage converts raw data into base band signals in accordance with

the particular wireless communication standard. The one or more intermediate frequency

stages mix the base band signals with one or more local oscillations to produce RF

signals. The power amplifier amplifies the RF signals prior to transmission via an

antenna.

7.3.3 Receiver in RF Transceiver:

The function of the receiver is to detect signals in the presence of noise and

interference, and provide amplification, down conversion and demodulation of the

detected the signal such that it can be displayed or used in a data processor. The RF

receiver receives an RF signal, converts the RF signal to an IF signal, and then converts

the IF signal to a base band signal, which it then provides to the base band processor. As

is also known, RF transceivers typically include sensitive components susceptible to

noise and interference with one another and with external sources. The RF receiver is

coupled to the antenna and includes a low noise amplifier, one or more intermediate

frequency stages, a filtering stage, and a data recovery stage.

The low noise amplifier receives an inbound RF signal via the antenna and

amplifies it. The one or more intermediate frequency stages mix the amplified RF signal

with one or more local oscillations to convert the amplified RF signal into a baseband

signal or an intermediate frequency (IF) signal. Typical transmit circuitry includes a

feedback loop (often a phase-locked loop, or PLL) that has a voltage-controlled oscillator

(VCO) and a loop filter circuitry. Phase locked loops (PLLs) are becoming increasingly

popular in integrated wireless transceivers as components for frequency generation and

modulation. PLLs are typically used for one of a variety of functions, including

frequency translation to up-convert a baseband (BB) signal to an intermediate frequency

(IF) or to up-convert a baseband or IF signal to RF prior to amplification by a power

amplifier and transmission. Inductive/capacitive (LC) oscillators are important elements

of RF transmitters, where the LC oscillators are used as master oscillators.


7.3.4 Design of RF Transceiver:

Transmitters and receivers for communication systems generally are designed

such that they are tuned to transmit and receive one of a multiplicity of signals having

widely varying bandwidths and which may fall within a particular frequency range.

In an RF receiver, an incoming RF signal is first passed through an RF band pass

filter to remove signal components outside of the frequency range of the desired signal.

The resulting filtered signal is then usually amplified by a low noise amplifier. A radio

frequency receiver includes a frequency converter for converting a received radio

frequency signal to an intermediate frequency (IF) signal. An IF filter is coupled to the

frequency converter for limiting the IF signal to the bandwidth of a communication

channel.

The band -limited signal is applied to a demodulator where the signal is processed

to recover the original baseband frequency signal. A low power RF receiver circuit

comprises a low noise preamplifier and double-balanced mixer, using novel monolithic

micro strip inductors and transformers for radio frequency IC (integrated circuit)

applications using submicron bipolar CMOS process technology.

A direct-conversion receiver in a radio communication system is configured to

have a varying gain in order to track the varying signal strength of the received RF signal.

Radio frequency (RF) receivers for cellular phone base stations must provide high

degrees of both selectivity and sensitivity. An important measure of a receiver's

performance is its sensitivity and one means for measuring this sensitivity is to compare

the measured bit error rate (BER) of a received signal with the signal to noise ratio.

Antennas are provided as accessories of RF receivers in order to provide the receivers

with the capability of receiving RF signals that are transmitted over the air.

7.4 SPI Protocol:

http://www.electronics-manufacturers.com/products/





SPI stands for serial peripheral interface

Fig 7.1 SPI protocol

It has four pins, they are, spi_cs, spi_clk, spi_SDI, spi_SD0.

Spi_cs pin is used to select the chip among the available chips. Spi_clk gives the

data rate of the transferring data.

This protocol is used to interface the MMC to the Microcontroller.


8. GOOGLE EARTH

Google Earth displays satellite images of varying resolution of the Earth’s

surface, allowing users to see things like cities and houses looking perpendicularly down

or at an oblique angle, with perspective (see also bird’s eye view). The degree of

resolution available is based some what on the points of interest and popularity, but most

land(except for islands) is covered in at least 15 meters of resolution.

Google Earth allows users to search for addresses for some countries, enter co-

ordinates, or simply use the mouse to browse to a location.

For large parts of the surface of the earth only 2D images are available, from

almost vertical photography. Viewing this from oblique angle, there is perspective in the

sense that objects which are horizontally far away are seen smaller, but of course it is

viewing a large photograph, not quite like a 3D view.

For other parts of the surface of the Earth 3D images of terrain and buildings are

available. Many people use the applications to add their own data, making them available

through various sources. Google earth is able to show all kinds of images overlaid on the

surface of the earth and is also a Web Map Service client. Google Earth supports

managing three-dimensional Geo-spatial data.

Recently, Google added a feature that allows users to monitor traffic speeds at

loops located every 200 yards in real-time. The ‘Westport3D’ model was created by 3D

imaging firm AM3TD using long distance laser scanning technology and digital

photography and is the first such model of an Irish town to be created. Google Earth can

be used to view areas subjected to wide spread disasters, if Google supplies up to date

images. For example after the 12 January 2010 Haiti earthquake images of Haiti were

made available on 17 January.


Fig: 8.1 top view of the ground from Google earth map


9. SOFTWARE DESCRIPTION

In our project we use two software’s. One is CCS Compiler micro vision for the

simulation of the program.

9.1 CCS Compiler Software:

CCS Compiler development tools for the Micro chip Microcontroller Architecture

support every level of software developer from the professional applications engineer to

the student just learning about embedded software.

The industry-standard CCS Compiler, Macro Assemblers, Debuggers, Real-time

Kernels, Single-board Computers, and Emulators support all 8051 derivatives and help

you get your projects completed on schedule.

9.1.1 Simulation:

The Simulator allows you to debug programs using only your PC using simulation

drivers provided by CCS Compiler and various third-party developers. A good simulation

environment, does much more than simply simulate the instruction set of a

microcontroller — it simulates your entire target system including interrupts, startup

code, on-chip peripherals, external signals, and I/O.

9.1.2 Use of Software for Execution of Microcontroller Programs:

CCS Compiler development tools for the MC architecture support every level of

software developer from the professional applications engineer to the student just

learning about embedded software development.

The industry-standard CCS Compiler, macro assemblers, debuggers, real, time

Kernels, Single-board computers and emulators support all microcontroller derivatives


and help you to get more projects completed on schedule. The CCS Compiler software

development tools are designed to solve the complex Problems facing embedded

software developers. Those are listed below.

9.1.3 Problems Facing Embedded Software Developers:

When starting a new project, simply select the microcontroller you the

device database and the µvision IDE sets all compiler, assembler, linker,

and memory options for you.

The CCS Compiler µ Vision debugger accurately simulates on-chip

peripherals (PC, CAN, UART, SPI, Interrupts, I/O ports, A/D converter,

D/A converter and PWM modules)of your aver device.

Simulation helps you understand h/w configurations and avoids time

wasted on setup problems. Additionally, with simulation, you can write

and test applications before target h/w is available.

When you are ready to begin testing your s/w application with target h/w,

use the MON51, MON390, MONADI, or flash MON51 target monitors,

the ISD51 In-System Debugger, or the ULINK USB-JTAG adapter to

download and test program code on your target system.

9.1.4 Creating a Project:

Select Project - New Project.

Select a directory and enter the name of the project file.

Select Project - Select Device and select an 8051, 251, or C16x/ST10

device from the Device

Create source files to add to the project.


Select Project - Targets, Groups, Files. Add/Files, select Source Group1,

and add the source files to the project.

Select Project - Options and set the tool options. Note when you select the

target device from the Device Database™ all-special options are set

automatically. You typically only need to configure the memory map of

your target hardware. Default memory model settings are optimal for most

9.1.5 Evaluation Software Limitations:

The compiler, assembler, linker, and debugger are limited to 2 Kbytes of object

code but source code may be any size. Programs that generate more than 2 Kbytes of

object code will not compile, assemble, or link.

9.2 Program Dumping Process:

The program must be dumped in the Microcontroller to run and given the output

of the project. We use the universal programmer for the dumping processes. The

programmer can be written the program in different types like ASM or C language. That

may be cannot directly dumped in Microcontroller. The written program can converted in

below types of format.

1. Hexa decimal code

2. Binary code

3. Intel

4. Motorola

In our project we write the program in C language and that may be converted into

Hexa decimal code then dumped in to Microcontroller using the CCS Compiler software.


9.3 coding:

#include <18F452.h> //For Microcontroller

#include <mmcsd.c> //For Memory Card

#include <fat.c> //For Fat file system inside Memory Card

#use delay(clock=20M)

#use rs232 (baud = 9600, xmit=PIN_C6,rcv=PIN_C7,stream=PC)

#use rs232 (baud = 4800, xmit=PIN_A1,rcv=PIN_A0,stream=GPS)

char data[120];

char gprmc[] = {"GPRMC"};

void get_GPS_GPRMC_data()

{

while(1)

{

fgets(data,GPS); //Gets the Serial Port Data from GPS Receiver

if(strstr(data,gprmc); //search for GPRMC in data

break;

}


}

void main(void)

{

char filename[20] = "myfile.txt"; //KSP '/' required before fname

char buffer[155];

char opt_buffer[100];

char valid_data[] = { ",A," };

char invalid_data[] = { ",V," };

int i; // pointer to the buffer

char f;

i = fat_init(); //Initialise FAT file system

if (i) //If init fails

{

fprintf(PC,"\r\n\nERROR INITIALIZING FAT\r\n\n");

}

else //OK


{

fprintf(PC,"Init done \r\n");

}

if (!input(PIN_D1)) //If D1 push button is pressed then Format the memory card

{

delay_ms(1000);

if(!input(PIN_D1))

{

FormatMedia("1048576"); //Format 1GB Card

delay_ms(5000); //It may take max of 5 seconds for formatting


fprintf(PC,"\r\nDeleted Old Data. Restart\r\n");

while(1); //wait indefinitely (restart the microcontroller)

}

}

output_high(PIN_D2); //Microcontroller Health Check Indicator

output_high(PIN_D3);

delay_ms(1000);

output_low(PIN_D3);

output_low(PIN_D2);

delay_ms(1000);



delay_ms(1000);

output_low(PIN_D3);

output_low(PIN_D2); //END

if(!input(PIN_B0)) //IF B0 push button is pressed then copy data to PC


{

if(!input(PIN_B0))

{

fprintf(PC,"\r\n*******Start GPS Data*******\r\n");

f = fopen(filename,'r'); //Open file in read mode

while(feof(f)) //while end of file

{

fgetstring(data,f); //copy

fputs(data,PC); //send data to PC

}

fclose(f); //close file

fprintf(PC,"\r\n*********END GPS Data*********\r\n");

fprintf(PC,"\r\nRestart and use Delete button for deleting this data.\r\n");

while(1); //wait indefinitely


}

}

f = fopen(filename,'a'); //Open/create file append mode

while(1)

{

get_GPS_GPRMC_data(); //Get data from GPS receiver

if(strstr(data,valid_data)) //Check for valid data.If the gps data contains ",A," then it's a

valid data

{

output_low(PIN_D3); //RED LED OFF

fputstring(data,f); //copy data to file (append)

output_high(PIN_D2); //Green LED ON indicating valid data

}

if(strstr(data,invalid_data)) //If the gps data contains ",V," then its invalid data


{

output_high(PIN_D3); //RED LED On indicating invalid data

output_low(PIN_D2); //Green LED OFF

}

output_low(PIN_D2); //LED OFF

output_low(PIN_D3); // LED OFF

fclose(f);

}

}


10.RESULT

10.1 The result from the GPS receiver:

The data from the GPS receiver which is stored in the MMC is in the NMEA

format.

The parameters such as Time, active (working), latitude, north, longitude, east,

speed, altitude and date and active (working) are given below.

$GPRMC,103049.000,A,1721.1071,N,07830.4403,E,0.17,96.65,160310,,,A

$GPRMC,103051.000,A,1721.1070,N,07830.4409,E,0.28,70.94,160310,,,A

$GPRMC,103053.000,A,1721.1071,N,07830.4412,E,0.45,48.30,160310,,,A

$GPRMC,103055.000,A,1721.1068,N,07830.4416,E,0.40,54.27,160310,,,A

$GPRMC,103057.000,A,1721.1065,N,07830.4423,E,0.34,70.40,160310,,,A

$GPRMC,103059.000,A,1721.1066,N,07830.4420,E,0.31,63.81,160310,,,A

$GPRMC,103101.000,A,1721.1067,N,07830.4421,E,0.32,58.63,160310,,,A

$GPRMC,103103.000,A,1721.1062,N,07830.4417,E,0.20,75.46,160310,,,A

$GPRMC,103105.000,A,1721.1062,N,07830.4417,E,0.30,71.81,160310,,,A

$GPRMC,103107.000,A,1721.1063,N,07830.4418,E,0.21,65.26,160310,,,A

$GPRMC,103109.000,A,1721.1063,N,07830.4419,E,0.14,65.26,160310,,,A

$GPRMC,103111.000,A,1721.1063,N,07830.4420,E,0.26,68.88,160310,,,A

$GPRMC,103113.000,A,1721.1064,N,07830.4421,E,0.33,55.95,160310,,,A


10.2 The result in the PC:

The data given by the GPS receiver which is stored in the MMC is transmitted the

PC with the help of the RF transceiver. In the PC the NMEA format data is converted to

the KMZ format and then when put in the GOOGLE Earth we get a map which is shown

below.

Fig.10.1 showing the route and lat, long, speed and alt from the Google Earth

The distance travelled is connected with a help of the line and the parameters such

as time, date, speed, altitude are shown.


11. APPLICATIONS AND ADVANTAGES

11.1 Applications:

• Latitude and longitude displayed can be used for location identification.

• Vehicle travel record management.

• Wild life researches.

• In every field to monitoring easily.

11.2 Advantages:

Usage of MMC card helps to store more data

Low cost

Since there is no requirement for a GSM modem it does not involve any data

transfer charges

Finds applications in different areas like Tourism, Navigation etc.


12. CONCULSION

Thus cab (vehicle) position logging system using GPS and MMC (Multimedia

Card) is constructed.

Firstly, integrating features of all the hardware components used. Presence of

every module has been reasoned out and placed carefully thus contributing to the best

working of the unit.

Secondly, using advanced components such as GPS and wireless network with the

help of the growing technology, the project has been successfully implemented.

In this project an effort has been made to study monitoring of the cab (vehicle)

and to implement it.

12.1 Future Scope:

With the use of high end micro controllers and graphical LCD displays we can

expect the data of the micro controller to be used dynamically during the journey it self to

find our position instead of positioning in the Google earths map after bringing the

memory card available to the PC.


13. APPENDIX

13.1 Schematic Diagram:

Fig 13.1 schematic diagram


13.2 Hardware Snapshot:

Fig 13.2 Snap Shot


13.3 Abbreviations:

AUC Authentication Center

BTS Base Transceiver Station

BSC Base Station Controller

CEPT Conference of European Posts and Telegraphs

EIR Equipment Identity Register.

ETSI European Telecommunication Standards Institute

HLR Home Location Register

IMEI International Mobile Equipment Identity

ITU International Telecommunication Union

IMSI International Mobile Subscriber Identity

LA Last known Location Area

MSISDN Mobile Subscriber ISDN

MSC Mobile service Switching Center

MAP Mobile Application Part

MSRN Mobile Station Roaming Number

MS Mobile station

MM Mobility Management layer

POTS Plain Old Telephone Service

PSTN Public switched telephone network

PSPDN packet switched public data network

PLMN Public land mobile network

Radio Resources management (RR)

RBS Remote Base station

SIM Subscriber Identity Module

TCU Transcoding Unit

TRAU Transcoding Rate and Adaptation Unit

VLR Visitor Location Register


14. BIBLIOGRAPHY

REFERENCES:

1. Global positioning systems inertial navigation, and integration Mohinders, Grewal,

Lawrence, R Weil, Angus p Andrews

2. GPS for DUMMIES BY Joel Mc Namara

3. National Marine Electronics Association: http://www.nmea.org

4. Torsten Baumbach's web site: http://pandora.inf.uni-jena.de/ttbb/

Web References:

http://en.wikipedia.org/wiki/GPS128*64

http://en.wikipedia.org/wiki/Category:MMC

http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en01026

http://www.howstuffworks.com

http://www.8051projects.com

http://www.8051projects.com/

http://www.howstuffworks.com/

http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en01026

http://en.wikipedia.org/wiki/GPS128*64

http://pandora.inf.uni-jena.de/ttbb/

Gps Based Cab Monitoring System

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