GPS AND GSM

7/27/2019 GPS AND GSM

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INTRODUCTION

In this modern, fast moving and insecure world, it is become a basic

necessity to be aware of ones safety. Maximum risks occur in situations where in

an employee travels for money transactions. Also the Company to which he

belongs should be aware if there is some problem. What if the person traveling can

be tracked and also secured in the case of an emergency.

In this Project it is proposed to design an embedded system which is used

for tracking and positioning of any vehicle by using Global Positioning System

(GPS) and Global system for mobile communication.

Here we are using PIC microcontroller is used for interfacing to

various hardware peripherals. The current design is an embedded application,

which will continuously monitor a moving Vehicle and report the status of the

Vehicle on demand. For doing so a PIC 16F877A microcontroller is interfaced

serially to a GSM Modem and GPS Receiver. A GSM modem is used to send the

position (Latitude and Longitude) of the vehicle from a remote place. The GPS

modem will continuously give the data i.e. the latitude and longitude indicating the

position of the vehicle. The GPS modem gives many parameters as the output, but

only the data coming out is read and displayed on to the LCD. The same data is


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sent to the mobile at the other end from where the position of the vehicle is

demanded. An EEPROM is used to store the mobile number.

The hardware interfaces to microcontroller are LCD display, GSM

modem and GPS Receiver. The design uses RS-232 protocol for serial

communication between the modems and the microcontroller. A serial driver IC is

used for converting TTL voltage levels to RS-232 voltage levels. When the request

by user is sent to the number at the modem, the system automatically sends a

return reply to that mobile indicating the position of the vehicle in terms of latitude

and longitude.


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BLOCK DIAGRAM


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RS 232

In telecommunications, RS-232 (Recommended Standard 232) is the

traditional name for a series of standards for serial binary single-ended data and

control signals connecting between aDTE(Data Terminal Equipment) and aDCE

(Data Circuit-terminating Equipment). It is commonly used in computer serial

ports. The standard defines the electrical characteristics and timing of signals, the

meaning of signals, and the physical size and pin out of connectors. The current

version of the standard is TIA-232-FInterface Between Data Terminal Equipment

and Data Circuit-Terminating Equipment Employing Serial Binary Data

Interchange, issued in 1997.

An RS-232 port was once a standard feature of a personal computer for

connections to modems, printers, mice, data storage, un-interruptible power

supplies, and other peripheral devices. However, the limited transmission speed,

relatively large voltage swing, and large standard connectors motivated

development of the universal serial bus which has displaced RS-232 from most of

its peripheral interface roles. Many modern personal computers have no RS-232

ports and must use an external converter to connect to older peripherals. Some RS-

232 devices are still found especially in industrial machines or scientific

instruments.
http://en.wikipedia.org/wiki/Telecommunicationshttp://en.wikipedia.org/wiki/Serial_communicationhttp://en.wikipedia.org/wiki/Telecommunicationshttp://en.wikipedia.org/wiki/Serial_communication


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Communication as defined in the RS232 standard is an asynchronous serial

communication method. The wordserialmeans, that the information is sent one bit

at a time.Asynchronous tells us that the information is not sent in predefined time

slots. Data transfer can start at any given time and it is the task of the receiver to

detect when a message starts and ends.

In computing, a serial port is a serial communication physical interface

through which information transfers in or out one bit at a time (in contrast to a

parallel port). Throughout most of the history of personal computers, data transfer

through serial ports connected the computer to devices such as terminals and

various peripherals.

While such interfaces as Ethernet, FireWire, and USB all send data as a

serial stream, the term "serial port" usually identifies hardware more or less

compliant to the RS-232 standard, intended to interface with a modem or with a

similar communication device. Modern computers without serial ports may require

serial-to-USB converters to allow compatibility with RS 232 serial devices. Serial

ports are still used in applications such as industrial automation systems, scientific

instruments, shop till systems and some industrial and consumer products. Server

computers may use a serial port as a control console for diagnostics.


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GSM MODEM

GSM modem is a specialized type of modem which accepts a SIM card, and

operates over a subscription to a mobile operator, just like a mobile phone. From

the mobile operator perspective, a GSM modem looks just like a mobile phone.

When a GSM modem is connected to a computer, this allows the computer to use

the GSM modem to communicate over the mobile network. While these GSM

modems are most frequently used to provide mobile internet connectivity, many of

them can also be used for sending and receiving SMS and MMS messages.


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A GSM modem can be a dedicated modem device with a serial,

USB or Bluetooth connection, or it can be a mobile phone that provides GSM

modem capabilities. For the purpose of this document, the term GSM modem is

used as a generic term to refer to any modem that supports one or more of the

protocols in the GSM evolutionary family, including the 2.5G technologies GPRS

and EDGE, as well as the 3G technologies WCDMA, UMTS, HSDPA and

HSUPA.

A GSM modem exposes an interface that allows applications such as Now

SMS to send and receive messages over the modem interface. The mobile operator

charges for this message sending and receiving as if it was performed directly on a

mobile phone. To perform these tasks, a GSM modem must support an extended

AT command set for sending/receiving SMS messages, as defined in the ETSI

GSM 07.05 and 3GPP TS 27.005 specifications.

GSM modems can be a quick and efficient way to get started with SMS,

because a special subscription to an SMS service provider is not required. In most

parts of the world, GSM modems are a cost effective solution for receiving SMS

messages, because the sender is paying for the message delivery.

A GSM modem can be a dedicated modem device with a serial, USB or

Bluetooth connection, such as the Falcom Samba 75. (Other manufacturers of


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dedicated GSM modem devices include Wavecom, Multitech and iTegno. Weve

also reviewed a number of modems on our technical support blog. To begin, insert

a GSM SIM card into the modem and connect it to an available USB port A GSM

modem could also be a standard GSM mobile phone with the appropriate cable and

software driver to connect to a serial port or USB port on your computer. Any

phone that supports the extended AT command set for sending/receiving SMS

messages, as defined in ETSI GSM 07.05 and/or 3GPP TS 27.005, can be

supported by the Now SMS & MMS Gateway. Note that not all mobile phones

support this modem interface.

Due to some compatibility issues that can exist with mobile phones, using a

dedicated GSM modem is usually preferable to a GSM mobile phone. This is more

of an issue with MMS messaging, where if you wish to be able to receive inbound

MMS messages with the gateway, the modem interface on most GSM phones will

only allow you to send MMS messages. This is because the mobile phone

automatically processes received MMS message notifications without forwarding

them via the modem interface.

It should also be noted that not all phones support the modem interface for

sending and receiving SMS messages. In particular, most smart phones, including

Blackberries, iPhone, and Windows Mobile devices, do not support this GSM


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modem interface for sending and receiving SMS messages at all at all.

Additionally, Nokia phones that use the S60 (Series 60) interface, which is

Symbian based, only support sending SMS messages via the modem interface, and

do not support receiving SMS via the modem interface.


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GPS

Introduction

The Global Positioning System (GPS) is a space-based satellite

navigation system that provides location and time information in all weather,

anywhere on or near the Earth. It is maintained by the United States government

and is freely accessible by anyone with a GPS receiver. The GPS program provides

critical capabilities to military, civil and commercial users around the world. In

addition, GPS is the backbone for modernizing the global air traffic system.

The GPS project was developed in 1973 to overcome the limitations of

previous navigation systems, integrating ideas from several predecessors, including

a number of classified engineering design studies from the 1960s. GPS was created

and realized by the U.S. Department of Defense (DOD) and was originally run

with 24 satellites. It became fully operational in 1994.

Fig. GPS satelites


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GPS technology was originally developed for defense purposes and later

brought to the consumer market as a navigation technology. However the price of

the technology went down and this prompted companies to find new applications

for the technology. GPS Tracking is one such innovation.

The Technology

Before we get into the applications of GPS, let us examine briefly how GPS

works. Well, GPS is based on the technique of trilateration. where GPS receivers

use this technique to calculate the co-ordinates of their location on earth. This

calculation is done by measuring the time signals from different satellites take to

reach them.

The signal strength and clock differences between the device and the

satellite network are adjusted by using signals from four separate satellites. This

way we get a fairly accurate reading of location, usually in an error range of within

100 metres.

The co-ordinates come into use to locate the device on a map. This map may

be displayed to the user who may either be the device holder or the tracker. The co-


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ordinates can also be used to calculate routes, navigate or as input into mapping

programs.

WORKING

A GPS receiver calculates its position by precisely timing the signals sent by

GPS satellites high above the Earth. Each satellite continually transmits messages

that include

the time the message was transmitted

precise orbital information (the ephemeris)

the general system health and rough orbits of all GPS satellites.

The receiver uses the messages it receives to determine the transit time of

each message and computes the distance to each satellite. These distances along

with the satellites' locations are used with the possible aid of trilateration,

depending on which algorithm is used, to compute the position of the receiver.

This position is then displayed, perhaps with a moving map display or latitude and

longitude; elevation information may be included. Many GPS units show derived

information such as direction and speed, calculated from position changes.

Three satellites might seem enough to solve for position since space has three

dimensions and a position near the Earth's surface can be assumed. However, even


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a very small clock error multiplied by the very large speed of light the speed at

which satellite signals propagate results in a large positional error. Therefore

receivers use four or more satellites to solve for both the receiver's location and

time. The very accurately computed time is effectively hidden by most GPS

applications, which use only the location. A few specialized GPS applications do

however use the time; these include time transfer, traffic signal timing,

and synchronization of cell phone base stations.

Although four satellites are required for normal operation, fewer apply in special

cases. If one variable is already known, a receiver can determine its position using

only three satellites. For example, a ship or aircraft may have known elevation.

Some GPS receivers may use additional clues or assumptions (such as reusing the

last known altitude, dead reckoning, inertial navigation, or including information

from the vehicle computer) to give a less accurate (degraded) position when fewer

than four satellites are visible.

GPS for Tracking

The simplest techniques in GPS tracking enable the user, who carries a

portable GPS device, to keep track of where they are, rectify if they have moved in

the wrong direction or follow the same path in future if necessary.


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Fig. GPS tracking

This device can be used in combination with other GPS devices such as GPS

phones. This way another user carrying a GPS phone can follow the initial user,

which is a useful application in field activities.

GPS tracking can also work in combination with broadcast technologies like

radio. Here, a GPS device calculates its position and also broadcasts the

information using a radio transmitter. This signal reaches a central command

location which has a GPS receiver. This way the central command can track the

wearer, store the information or relay it to another party depending on the

requirements.


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This has many uses- for defense and police personnel as well as households. For

example, an anxious parent can track where their ward is at any time of the day or

night.

GPS in Vehicle Tracking

One application of GPS is for tracking vehicles, where GPS devices are

attached to vehicles with a distinctive identification like a chassis number. The

principle is similar to a tracking device worn by a human; however the system is

integrated with the vehicles electronic system.

This way, the vehicle does not need a separate car navigation system.

Further, the GPS technology makes it possible to relay this information through a

radio or cell phone. Another application of the technology is for locating vehicles.

The police can track a stolen vehicle fitted with a GPS device. GPS devices can

also be used to pass alerts to the driver. For instance, a driver can be alerted of the

approach of a service center while he is on the road in unfamiliar territory.

Fleet Coordination

GPS technology can also be extended to coordinate vehicle tracking. Thus

several vehicles going to the same destination can share location information.

Vehicle tracking and GPS fish-finder unit combinations have been used


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successfully to help fishing boats locate, track and catch large schools of fish.

However the overall technology is more sophisticated here, as elements like

gauging depth, checking tide timings etc come into the picture.

Fleet tracking has an important place in military operations. Units out of line

of sight can share their location information. The often inaccurate map coordinate

method of the past can thus be replaced with much higher accuracy now.

Consumer Applications

While originally a military project, GPS is considered a dual-

use technology, meaning it has significant military and civilian applications. GPS

has become a widely deployed and useful tool for commerce, scientific uses,

tracking, and surveillance. GPS's accurate time facilitates everyday activities such

as banking, mobile phone operations, and even the control of power grids by

allowing well synchronized hand-off switching.

Apart from military, commercial fishing and aviation applications, GPS

tracking can also work with existing systems like cell phones and vehicles. A point

of service is often involved here, to keep track of the location. This brings down

the cost of the consumer unit and users can avail the technology at attractive prices.


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VOICE IC


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Here we are using APR 9600 voice ic for recording the message to play. It is

a re-recordable Voice IC in which we can store message up to 60 second play

back.

Fig. APR 9600 voice IC

APR9600 is sound record/replay IC incorporating flash analogue storage

technique. Recorded sound is retained after power supply is removed from the

module. The replayed sound exhibits high quality with a low noise level.

Sampling rate for a 60 second recording period is 4.2 kHz that gives a sound

record/replay bandwidth of 20Hz to 2.1 kHz. However, by changing an oscillation

resistor, a sampling rate as high as 8.0 kHz can be achieved. This shortens the total

length of sound recording to 32 seconds.

Total sound recording time can be varied from 32 seconds to 60 seconds.

The IC can operate in one of two modes: serial mode and parallel mode. In serial


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access mode, sound can be recorded in 256 sections. In parallel access mode,

sound can be recorded in 2, 4 or 8 sections. The IC can be controlled simply using

push button keys. It is also possible to control the IC using external digital circuitry

such as micro-controllers and computers.

Features :

Single-chip, high-quality voice recording & playback solution.

- No external ICs required

- Minimum external components

Non-volatile Flash memory technology.

- No battery backup required

User-Selectable messaging options.

- Random access of multiple fixed-duration messages

- Sequential access of multiple variable-duration messages

User-friendly, easy-to-use operation.

- Programming & development systems not required

- Level-activated recording & edge-activated play back switches

Low power consumption.

- Operating current: 25 mA typical

- Standby current: 1 uA typical

- Automatic power-down


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Chip Enable pin for simple message expansion.

Fig . Pin diagram of APR 9600

General Description :

The APR9600 device offers true single-chip voice recording, non-volatile

storage, and playback capability for 40 to 60 seconds. The device supports both

random and sequential access of multiple messages. Sample rates are user-

selectable, allowing designers to customize their design for unique quality and

storage time needs. Integrated output amplifier, microphone amplifier, and AGC

circuits greatly simplify system design. the device is ideal for use in portable voice

recorders, toys, and many other consumer and industrial applications. APLUS

integrated achieves these high levels of storage capability by using its proprietary

analog/multilevel storage technology implemented in an advanced Flash non-


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volatile memory process, where each memory cell can store 256 voltage levels.

This technology enables the APR9600 device to reproduce voice signals in their

natural form. It eliminates the need for encoding and compression, which often

introduce distortion.

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GPS AND GSM