telemedicine system using gsm wireless network chapter-1

Telemedicine system using GSM wireless network

1 | P a g e C . U . S H A H C O L L E G E O F E N G & T E C H .

CHAPTER-1:

1.1 INTRODUCTION:

ACCORDING to an estimate, given by the World Health Organization (WHO),

cardiovascular disease kills almost seventeen million people around the globe each year along

with twenty million people at a risk of sudden heart failure.

Some of these lives can often be saved if acute care and cardiac surgery is provided within

the so-called golden hour. So the need for advice on first hand medical attention and

promotion of good health by patient monitoring and follow-up becomes inevitable. Hence,

patients who are at risk require that their cardiac health to be monitored frequently whether

they are indoors or outdoors so that emergency treatment is possible. Telemedicine is widely

considered to be part of the inevitable future of the modern practice of medicine.

It is gaining more and more momentum as a new approach for patients' surveillance outside

of hospitals (at home) to encourage public safety, a ciliate early diagnosis, treatment, and for

increased convenience. Defined as the “use of advanced Tele Communication technologies “

to exchange the information about the patient's health care status and provide health care

services across is now currently being used by doctors, hospitals and other healthcare

providers around the world with conventional mode of treatment. Telemedicine systems are

already available to enable the doctor to monitor a patient remotely for home care emergency

applications. Nowadays, Wireless networking is an emerging technology that will allow

different users to access electronically, regardless of their geographic topography. The use of

wireless communication between mobile users has become increasingly popular due to the

advancements in computer and wireless technologies. Implementation of wireless technology

in the existing heart rate monitoring system eliminates the physical constraints imposed by

hard-wired link and allows users to conduct own check up at anytime anywhere.

Moreover, newer cellular access technologies, such as Third generation (3G), and others

provide much higher data transmission speeds (rates) than basic second generation (2G) GSM

cellular system offering future telemedicine solutions endless choices for high-end designs.

These relatively new wireless technologies are deployed mostly in or around crowded high

income metropolitan areas for our proposed scheme.



But the majority (80.8%) of the 3.7 billion cellular phone users in the world are still 2G GSM

users. Hence, we describe a telemedicine system based on mobile messaging service namely:

Short Messaging Service (SMS), which is an integral part of the original 2GGSMcellular

system and subsequent generations since all new phones are SMS capable. Our project aims

at detecting the cardiac disorder of the patient in advance thereby reducing the critical level

of the patient by following precautionary measures at an earlier instant.

1.2 OBJECTIVE OF THE PROJECT:

A mobile telemedicine system includes a small portable hand-held device, such as a

mobile phone, which relays the information collected from patients to the healthcare

provider using GSM wireless network.

GSM system used to support, control, and monitor patients in relatively large areas

by delivering patients’ vital signs and medical information to remote medical

facilities.

Increasing the chances of timely and appropriate actions.

This system provides mobility to the doctor and the patient.



CHAPTER-2:

2.1 BRIEF LITERATURE REVIEW:

2.1.1 ABOUT TELEMEDICINE:

Telemedicine can be defined as the delivery of health care and sharing of medical knowledge

over a distance using telecommunication means. It aims at providing expert based medical

care to any place that health care is needed. Telemedicine as a concept was introduced about

30 years ago when telephone and fax machines were the first telecommunication means used.

In recent years, several telemedicine applications have been successfully implemented over

wired communication technologies like POTS, and ISDN. However, nowadays, modern

wireless telecommunication means like the GSM and GPRS and the forthcoming UMTS

mobile telephony standards, as well as satellite communications, allow the operation of

wireless telemedicine systems freeing the medical personnel and/or the subject monitored

bounded to fixed locations.

Telemedicine applications, including those based on wireless technologies span the areas of

emergency health care, telecardiology, teleradiology, telepathology, teledermatology,

teleophtlalmology, teleoncology, and telepsychiatry. In addition, health telematics

applications enabling the availability of prompt and expert medical care have been exploited

for the provision of health care services at understaffed areas like rural health centers,

ambulance vehicles, ships, trains, airplanes as well as for home monitoring.

2.1.2 WIRELESS TECHNOLOGIES:

There are various wireless technology for implementation of telemedicine system such as,

GSM technology

Satellite

Wireless local area network (WLAN)

Radio frequency

Bluetooth



The first technology, GSM is a system currently in use, and is the second generation (2G) of

the mobile communication networks. When it is in the standard mode of operation, it

provides data transfer speeds of up to 9.6 kbps. Through the years a new technique was

introduced in the GSM standard called High Speed Circuit Switched Data HSCSD. This

technology makes it possible to use several time slots simultaneously when sending or

receiving data, so the user can increase the data transmission to 14.4 kbps (an increase of

50%) or even triple at 43.3 kbps. The evolution of mobile telecommunication systems from

2G to 2.5G (iDEN 64 kbps, GPRS 171 kbps, EDGE 384 kbps) and subsequently to 3G (W-

CDMA, CDMA2000, TD-CDMA) systems will facilitate the provision of faster data transfer

rates thus enabling the development of telemedicine systems that require high data transfer

rates and are currently only feasible on wired communication networks.

Second technology is Satellite systems are able to provide a variety data transfer rates starting

from 2.4 kbps and moving to high-speed data rates of up to 2x64 kbps and even more.

Satellite links also have the advantage of operating all over the world.

Third is WLAN is a flexible data communications system implemented as an extension to or

as an alternative for a wired LAN. Using radio frequency (RF) technology, WLANs transmit

and receive data over the air, minimizing the need for wired connections. Thus, WLANs

combine data connectivity with user mobility, becoming very popular in a number of vertical

markets, including the healthcare, retail, manufacturing, warehousing, and academia. By

using bluetooth telemedicine system is developed for the shorter range of transmission .

Today wireless LANs are becoming more widely recognized as a general purpose

connectivity alternative for a broad range of applications, forseeing that this technology will

penetrate the health sector in the near future.

2.1.3 DESIGN GUIDELINE:

The development of these systems was guided by the following design guidelines:

easy-to-use interface – the system should provide simple interfaces for the health

provider;

controllability – the system should support remote control functions. The healthcare

provider should be empowered with the ability to control the media content according



to medical specialties or his/her personal preference. For example, the health provider

is allowed to control ECG sample rate, video frame rate, and image quality, etc.;

device adaptability – the system should meet th capabilities of the computing device

(e.g. laptop, PDA or mobile phone) on which it runs;

media adaptability – the system should provide support for different medical data,

such as vital bio-signals, images, video, and patient information; and

modular design – the system should have a modular design so that it allows for the

development of a roadmap for growth that can accommodate future generations of

functionality.

2.2 DETAILED DESCRIPTION:

Recently, the health care sensors are playing a vital role in hospitals. The patient monitoring

systems is one of the major improvements because of its advanced technology. A wireless

patient monitoring system to measure heartbeat of the patient by using embedded technology

is developed.

So we are here, just connecting the heartbeat sensor so that simultaneously we can monitor

the patient’s condition.

This project describes the design of a simple, low-cost microcontroller based heart rate

measuring device with LCD output. Heart rate of the subject is measured from the index

finger using IRD (Infra Red Device sensors and the rate is then averaged and displayed on a

text based LCD).

The device alarms when the heart beat exceed the provided threshold value. This threshold

value is defined by the programmer at the time of programming the microcontroller 89C8052.

The threshold value given for the project is as 20 to 120 pulses per minute.

This information i.e. the Heart Rate is then transmitted wirelessly to the doctor which in not

in the vicinity of the patient through GSM technique. The sensors measure the information

and transmit it through GSM Modem on the same frequency as on which cell phones work.



2.3 IDEA of the TRANSMISSION BETWEEN TRANSMITTER AND

RECEIVER:

Fig2.3.1 [basic idea of gsm based tool kit showing transmitter and receiver part and the

information as the sms ]


CHAPTER 3:

3.1 BLOCK DIAGRAM:

Fig3.1.1 [Block

Here, in block diagram the primary

rate from the patients finger. In

receive the signal from the patient

an receiver photo diode or LDR(light

the amplifier which amplify the

amplified signal is given to the micro

to the program set by programmer.

to 120 pulses per minute. The

microcontroller is transmited wirelessly

For connecting GSM modem to

communication port rs-232. This

the information of the patient transmited

cell phone work.


diagram of GSM based telemedicine system]

primary portion is the heart rate monitor which measure

heart rate sensor transmitter transmit the signal

patient finger. As a transmitter high brightness LED is

LDR(light dependent resistor) is used. This signal is

the signal because the receiver output is in milivolt.

microcontroller. Microcontroller process the signal

programmer. The value of pulse rate define by programmer

The output is displayed on the LCD. The output

wirelessly by using the GSM modem to the users

the microcontroller IC max-232 is used to interface

This rs-232 is directly connected with the GSM modem.

transmited by GSM modem on the same frequency


measure the pulse

signal and receiver

is used and as

then given to

milivolt. Then this

signal according

programmer is about 20

output of the

users cell phone.

interface the serial

modem. Then

frequency on which



3.2 COMPONENTS:

The Major Components used in Our Project are:

1. MICROCONTROLLER 89c52

2. MAX 232

3. LCD DISPLAY

4. SIM 300 GSM MODEM

5. CRYSTAL 11.0592 MHz

6. BUZZER

7. CAPACITORS

8. RESISTORS

9. CONNECTING WIRES

10. POWER SUPPLY

3.3. HEART RATE MONITOR:

Heart beat sensor is designed to give digital output of heat beat when a finger is placed on it.

When the heart beat detector is working, the beat LED flashes in unison with each heart beat.

This digital output can be connected to microcontroller directly to measure the Beats Per

Minute (BPM) rate. It works on the principle of light modulation by blood flow through

finger at each pulse.

3.3.1 FEATURES:

Microcontroller based SMD design

Heat beat indication by LCD

Instant output digital signal for directly connecting to microcontroller

Compact Size

Working Voltage +5V DC

3.3.2 APPLICATIONS:

Digital Heart Rate monitor

Patient Monitoring System

Bio-Feedback control of robotics and applications



3.3.3 USING THE SENSOR:

Connect regulated DC power supply of 5 Volts. Black wire is Ground, Nextmiddle

wire is Brown which is output and Red wire is positive supply. Thesewires are also

marked on PCB.

To test sensor you only need power the sensor by connect two wires +5V andGND.

You can leave the output wire as it is. When Beat LED is off the output isat 0V.

Put finger on the marked position, and you can view the beat LED blinking oneach

heart beat.

The output is active high for each beat and can be given directly to microcontroller for

interfacing applications.

3.3.4 WORKING PRINCIPLE:

fig3.3.4.1 [Principle of heart rate]

The sensor consists of a super bright red LED and light detector. The LED needs to besuper

bright as the maximum light must pass spread in finger and detected by detector. Now, when

the heart pumps a pulse of blood through the blood vessels, the finger becomes slightly more

opaque and so less light reached the detector. With each heart pulse the detector signal varies.

This variation is converted to electrical pulse. This signals amplified and triggered through an

amplifier which outputs +5V logic level signal.

Following figure shows signal of heart beat and sensor signal output graph.Fig.2 shows actual

heart beat received by detector (Yellow) and the trigger point of sensor (Red) after which the

sensor outputs digital signal (Blue) at 5V level.



Fig3.3.4.2 [signal of heart beat and sensor signal output graph]

Figure shows target pulse rates for people aged between 20 and 70. The target range is the

pulse rate needed in order to provide suitable exercise for the heart. For a 25-year old, this

range is about 140-170 beats per minute while for a 60-year old it is typically between 115

and 140 beats per minute.

Fig3.3.4.3 [Graph of Pulse rate for various aged]



3.3.5 TWO STAGE AMPLIFIER:

The Microcontroller AT89c52 is used to sense the heart Beat. The Red high intensity light

emitted by led initially falls on LDR .

fig3.3.5.1 [Sensing circuit of heart rate monitor]

When a patient places his finger in between LED and LDR the light is restricted by the

finger .The intensity of light penetration decreases if the blood is pumped into the finger .If

the blood is not pumped then the light intensity is high .This high and low light intensity

helps to measure heartbeat .Actually light falling on LDR cuts due to blood movement .The

duration of light disturbed is measured which gives the time duration of each heart beat pulse

,inverse of this time gives the heartbeat count per minute .This signal is amplified in two

stages using dual operational amplifiers.

The purpose of the two-stage amplifier circuit is to do preliminary amplification and filtering

of the input signal. The objective is to improve the signal to noise ratio by removing noise,

and bolstering the signal voltage amplitude, because the waveform from the photo detector is

noisy and has small signal amplitude. Using an oscilloscope for measurement, the typical

amplitude range for the raw heart beat waveform was between 180 – 250 mV, which included

noise. It was difficult to determine the peaks of the waveform just by viewing the raw input

signal.

The circuitry used to amplify and filter the input heart beat signal from the pulse optical

sensor is shown in Figure 5. The heart beat signal first goes through a 2.2uF capacitor which

actually limits the signal. The impedance of a capacitor is 1/jwC, where j = the imaginary



term, w = frequency in radians per second, and C is the capacitance in farads. At lower

frequencies, the capacitor acts like an impedance that is inversely proportional to the

frequency. As signal frequency decreases, the capacitor impedance increases. The signal then

enters the first stage amplifier. The inverter stage is non-inverting, and the designed gain is

set to be the ratio of the feedback resistor to the resistor pulling the signal down. In the

circuit, the desired gain from the first stage is R3 / R7 = 1MΩ / 47kΩ = 21.276. The feedback

capacitor helps to filter out higher frequency noise by acting as a short from the output of the

amplifier to the negative input. This diverts the noise signals from entering the next stage of

the circuit – the potentiometer.

The potentiometer is placed between the output of the first stage and the input of the second

stage amplifier. The potentiometer acts as a variable resistor and changes its resistance,

letting in differing amounts of the signal from the 1st stage to the 2nd. It acts like a “volume”

control knob on a stereo. The addition of the potentiometer gives user’s flexibility in tuning

the output signal amplitude. For example, if user is calmly sitting with little movement, only

small signal will be necessary. If user is out jogging, there is a lot of movement, and the

circuit may need higher signal amplitude to work. The signal then goes through another 2.2uF

capacitor and is limited before it enters the second stage amplifier which is designed to be the

same as the first stage. The two LEDs in series are only used to drop the voltage from the

adjacent node.

Experiments were then done to explore and verify the design. An oscilloscope was used to

probe the circuit at three test points. Channel 1 is at the input of the circuit, channel 2 is at the

output of the 1st stage operational amplifier, and channel 3 or 4 is at the overall output of the

2-stage amplifier.


Fig3.3.5.2

As seen in Figure, the input signal (ch.1) from the photo detector in the finger sensor is a

noisy and it is hard to see changes in signal amplitudes (where a

of the first stage (ch.2) amplifier, the signal is still a noisy, but amplitude is noticeably

increased, and the heart beats are discernable. At the output after both stages of the amplifier,

a distinct heart beat pattern is seen with a voltage swing of 0V~2V. The potentiometer is set

to the middle of its range. Therefore the output signal is at an amplitude of about 2V. If the

potentiometer is tuned so that its variable resistance is smaller, the output voltage amplitude

will be higher. The output after amplification is obtained at pin number 7 of OP

to microcontroller.


Fig3.3.5.2 (Oscilloscope view)


noisy and it is hard to see changes in signal amplitudes (where a heart beat is). At the output



een with a voltage swing of 0V~2V. The potentiometer is set



The output after amplification is obtained at pin number 7 of OP-



heart beat is). At the output



een with a voltage swing of 0V~2V. The potentiometer is set



-AMP and fed



3.4 DESIGN CONSIDERATION:

3.4.1 POWER SUPPLY:

fig.3.4.1.1 [5 volt power supply]

1. Diode: diode 1n4007 is use as a Bridge Rectifier. Which convert AC signal to DC

signal.

2. Capacitor: capacitor 1000µF and 1 µF. which gives pulsating DC voltage is filtered

by capacitor.

3. Regulator IC( 7805): the 7805 is a voltage regulator IC to obtain constant 5v supply

3.4.2 SENSING CIRCUIT:

IC LM358: 2.2uF capacitor which actually limits the signal.

The gain of first amplifier is,

Gain = R3 / R7

= 1MΩ / 47KΩ

= 21.2k

3.5 MICROCONTROLLER (AT89C52):

The AT89C52 is a low-power, high-performance CMOS 8-bit microcomputer with 8K bytes

of Flash programmable and erasable read only memory (PEROM). The device is

manufactured using Atmel’s high-density nonvolatile memory technology and is compatible

with the industry-standard 80C51 and 80C52 instruction set and pinout. The on-chip Flash



allows the program memory to be reprogrammed in-system or by a conventional nonvolatile

memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip,

the Atmel AT89C52 is a powerful microcomputer which provides a highly-flexible and cost-

effective solution to many embedded control applications.

fig3.5.1 [Pin diagram of AT89C52 microcontroller]

3.6 LCD DISPLAY:

LCD (Liquid Crystal Display) screen is an electronic display module and find a wide range of

applications. A 16x2 LCD display is very basic module and is very commonly used in

various devices and circuits. These modules are preferred over seven segments and other



multi segment LEDs. The reasons being: LCDs are economical; easily programmable; have

no limitation of displaying special & even custom characters (unlike in seven

segments), animations and so on.

A 16x2 LCD means it can display 16 characters per line and there are 2 such lines. In this

LCD each character is displayed in 5x7 pixel matrix. This LCD has two registers, namely,

Command and Data.

The command register stores the command instructions given to the LCD. A command is an

instruction given to LCD to do a predefined task like initializing it, clearing its screen, setting

the cursor position, controlling display etc. The data register stores the data to be displayed

on the LCD. The data is the ASCII value of the character to be displayed on the LCD. Click

to learn more about internal structure of a LCD.

3.6.1 PIN DIAGRAM:

fig3.6.1.1 [Pin diagram of 16×2 LCD]

3.6.2 PIN DESCRIPTION:

Pin

NoFunction Name

1 Ground (0V) Ground



2 Supply voltage; 5V (4.7V – 5.3V) Vcc

3 Contrast adjustment; through a variable resistor VEE

4 Selects command register when low; and data register when high Register Select

5 Low to write to the register; High to read from the register Read/write

6 Sends data to data pins when a high to low pulse is given Enable

7

8-bit data pins

DB0

8 DB1

9 DB2

10 DB3

11 DB4

12 DB5

13 DB6

14 DB7

15 Backlight VCC (5V) Led+

16 Backlight Ground (0V) Led-

3.7 MAX-232:

The MAX232 IC is used to convert the TTL/CMOS logic levels to RS232 logic levels during

serial communication of microcontrollers with PC. The controller operates at TTL logic level

(0-5V) whereas the serial communication in PC works on RS232 standards (-25 V to + 25V).

This makes it difficult to establish a direct link between them to communicate with each

other.



The intermediate link is provided through MAX232. It is a dual driver/receiver that includes

a capacitive voltage generator to supply RS232 voltage levels from a single 5V supply. Each

receiver converts RS232 inputs to 5V TTL/CMOS levels. These receivers (R1 & R2) can

accept ±30V inputs. The drivers (T1 & T2), also called transmitters, convert the TTL/CMOS

input level into RS232 level.

The transmitters take input from controller’s serial transmission pin and send the output to

RS232’s receiver. The receivers, on the other hand, take input from transmission pin of

RS232 serial port and give serial output to microcontroller’s receiver pin. MAX232 needs

four external capacitors whose value ranges from 1µF to 22µF.

Microcontroller MAX232 RS232

Tx T1/2 In T1/2 Out Rx

Rx R1/2 Out R1/2 In Tx

3.8 RS-232:

In telecommunications, RS-232 is a standard for serial binary data signals connecting

between a DTE (Data terminal equipment) and a DCE (Data Circuit-terminating Equipment).

It is commonly used in computer serial ports. In RS-232, data is sent as a time-series of bits.

Both synchronous and asynchronous transmissions are supported by the standard. In addition

to the data circuits, the standard defines a number of control circuits used to manage the

connection between the DTE and DCE. Each data or control circuit only operates in one

direction that is, signaling from a DTE to the attached DCE or the reverse. Since transmit

data and receive data are separate circuits, the interface can operate in a full duplex manner,

supporting concurrent data flow in both directions. The standard does not define character

framing within the data stream, or character encoding.



3.8.1 PIN DIAGRAM:

Fig3.8.1.1 [pin diagram of RS-232]

Functions Signals PIN DTE DCE

Data TxD 3 Output Input

RxD 2 Input Output

Handshake

RTS 7 Output Input

CTS 8 Input Output

DSR 6 Input Output

DCD 1 Input Output

STR 4 Output Input

Common Com 5 -- --

Other RI 9 Output Input

3.8.2 RS-232 SIGNALS:

1. Transmitted Data (TxD)

Data sent from DTE to DCE.

2. Received Data (RxD)



Data sent from DCE to DTE.

3. Request To Send (RTS)

Asserted (set to 0) by DTE to prepare DCE to receive data. This may require action on the

part of the DCE, e.g. transmitting a carrier or reversing the direction of a half-duplex line.

4. Clear To Send (CTS)

Asserted by DCE to acknowledge RTS and allow DTE to transmit.

5. Data Terminal Ready (DTR)

Asserted by DTE to indicate that it is ready to be connected. If the DCE is a modem, it should

go "off hook" when it receives this signal. If this signal is de-asserted, the modem should

respond by immediately hanging up.

6. Data Set Ready (DSR)

Asserted by DCE to indicate an active connection. If DCE is not a modem (e.g. a null-modem

cable or other equipment), this signal should be permanently asserted (set to 0), possibly by a

jumper to another signal.

7. Carrier Detect (CD)

Asserted by DCE when a connection has been established with remote equipment.

8. Ring Indicator (RI)

Asserted by DCE when it detects a ring signal from the telephone line.

3.8.3 RTS/CTS Handshaking:

The standard RS-232 use of the RTS and CTS lines is asymmetrical. The DTE asserts RTS

to indicate a desire to transmit and the DCE asserts CTS in response to grant permission. This

allows for half-duplex modems that disable their transmitters when not required and must

transmit a synchronization preamble to the receiver when they are re-enabled. There is no

way for the DTE to indicate that it is unable to accept data from the DCE. A non-standard

symmetrical alternative is widely used: CTS indicates permission from the DCE for the DTE

to transmit, and RTS indicates permission from the DTE for the DCE t1o transmit. The

"request to transmit" is implicit and continuous. The standard defines RTS/CTS as the

signaling protocol for flow control for data transmitted from DTE to DCE. The standard has

no provision for flow control in the other direction. In practice, most hardware seems to have

repurposed the RTS signal for this function. A minimal “3-wire” RS-232 connection

consisting only of transmits data, receives data and Ground, and is commonly used when the

full facilities of RS-232 are not required. When only flow control is required, the RTS and

CTS lines are added in a 5-wire version. In our case it was imperative that we connected the



RTS line of the microcontroller (DTE) to ground to enable receipt of bit streams from the

modem.

3.8.4 Specifying Baud Rate, Parity & Stop bits:

Serial communication using RS-232 requires that you specify four parameters: the baud rate

of the transmission, the number of data bits encoding a character, the sense of the optional

parity bit, and the number of stop bits. Each transmitted character is packaged in a character

frame that consists of a single start bit followed by the data bits, the optional parity bit, and

the stop bit or bits. A typical character frame encoding the letter "m" is shown here.

We specified the parameters as baud rate – 2400 bps, 8 data bits, no parity, and 1 stop bit

(2400-8-N-1). This was set in pre-operational phase while setting up the modem through the

hyper terminal, as per the serial transmission standards in 8051 microcontroller.

3.9 GSM MODEM:

A GSM modem is a wireless modem that works with a GSM wireless network. A wireless

modem behaves like a dial-up modem. The main difference between them is that a dial-up

modem sends and receives data through a fixed telephone line while a wireless modem sends

and receives data through radio waves. Like a GSM mobile phone, a GSM modem requires a

SIM card from a wireless carrier in order to operate.

SIM300 is basic GSM modem used for communication purpose at lower cost.



Fig.3.9.1 [SIM300 GSM modem]

3.9.1 FEATURES:

Low cost

GSM/GPRS modem using simcom-3oo module

RS 232 interface DB port

Voice communication port

On board voltage regulator

SMA connector for antenna connection

The sim300 offers GSM/GPRS 900/1800 MHz for voice, sms, data, fax

This module can be easily interfaced with AT commands

3.9.2 HOW TO USE:

1. Connect 12volt AC/2 A power supply

2. Serial cable connection to computer

3. Open hyper terminal, set com port….bit per second 9600, databit 1, paritly none , stop

bit 1, flow control none



4. Property go setting asch setup, send line end with line feeds tick, append line feeds to

incoming line, end tick.

Computers use AT commands to control modems. Both GSM modems and dial-up modems

support a common set of standard AT commands. GSM modem can be used just like a dial-

up modem. In addition to the standard AT commands, GSM modems support an extended set

of AT commands. These extended AT commands are defined in the GSM standards. With the

extended AT commands, various things can be done:-

Reading, writing and deleting SMS messages.

Sending SMS messages.

Monitoring the signal strength.

Monitoring the charging status and charge level of the battery.

Reading, writing and searching phone book entries.

The number of SMS messages that can be processed by a GSM modem per minute is very

low -- only about six to ten SMS messages per minute.

3.9.3 Accessing GSM MODEM using Microsoft HyperTerminal:

Microsoft HyperTerminal is a small program that comes with Microsoft Windows. We use it

to send AT commands to the GSM modem. It can be found at

Start -> Programs -> Accessories -> Communications -> HyperTerminal.

Before programming our SMS application, it is required to check if the GSM modem and

SIM card are working properly first. The MS HyperTerminal is a handy tool when it comes

to testing the GSM device. It is a good idea to test the GSM devices beforehand.

When a problem occurs, sometimes it is difficult to tell what causes the problem. The cause

can be the program, the GSM device or the SIM card. If GSM device and SIM card with MS

HyperTerminal and they operate properly, then it is very likely that the problem is caused by

the program or other hard wares.

For Linux users, Mincom can be used instead of HyperTerminal.



3.9.4 Testing of GSM MODEM:

To use MS HyperTerminal to send AT commands to the GSM modem, the following

procedure is followed:

1. We put a valid SIM card into the GSM modem. We can obtain a SIM card by

subscribing to the GSM service of a wireless network operator.

2. Since in our case the modem drivers were pre installed, we need not to install any such

drivers.

3. Then we start up MS HyperTerminal by selecting Start -> Programs -> Accessories ->

Communications -> HyperTerminal.

4. In the Connection Description dialog box (as shown in the screenshot given below), we

enter any name and choose an icon we like for the connection. Then we click the OK

button.

5. In the Connect To dialog box, choose the COM port that your mobile phone or GSM

modem is connecting to in the Connect using combo box. For example, choose COM1 if

your mobile phone or GSM modem is connecting to the COM1 port. Then click the OK

button.(Sometimes there will have more than one COM port in the Connect using combo



box. To know which COM port is used by your mobile phone or GSM modem, follow

the procedure below.

6. The Properties dialog box comes out. Enter the correct port settings for your mobile

phone or GSM modem. Then click the OK button.

7. Type "AT" in the main window. A response "OK" should be returned from the mobile

phone or GSM modem. Type "AT+CPIN?" in the main window. The AT command

"AT+CPIN?" is used to query whether the mobile phone or GSM modem is waiting for a

PIN (personal identification number, i.e. password). If the response is "+CPIN:

READY", it means the SIM card does not require a PIN and it is ready for use. If your

SIM card requires a PIN, you need to set the PIN with the AT command

"AT+CPIN=<PIN>".

8. If you get the responses above, your mobile phone or GSM modem is working properly.



CHAPTER-4: INTERFACING

4.1 MICROCONTROLLER – MODEM INTERFACING:

4.1.1 DTE and DCE:

The terms DTE and DCE are very common in the data communications market. DTE is short

for Data Terminal Equipment and DCE stands for Data Communications Equipment. As the

full DTE name indicates this is a piece of device that ends a communication line, whereas the

DCE provides a path for communication.

For example, the PC is a Data Terminal (DTE). The two modems (yours and that one of your

provider) are DCEs, they make the communication between you and your provider possible.

Fig4.1.1.1 [Logic diagram of interfacing between controller and rs-232]

For interfacing microcontroller and GSM modem we have to design RS-232,MAX-232 to

TTL converter board. This board Work with 5V and 3.3V Power. This converter can be used

on any Micro controller - PIC, Atmel or other which has TTL serial communications that

needs to be converted to RS232.



Fig4.1.1.2 [Circuit for Interfacing between max-232 and rs-232]

Text message may be sent through the modem by interfacing only three signals of the

serial interface of modem with microcontroller i.e. TxD, RxD and GND.

In this scheme RTS and CTS signals of serial port interface of GSM Modem are

connected with each other.

The transmit signal of serial port of microcontroller is connected with transmit signal

(TxD) of the serial interface of GSM Modem while receive signal of microcontroller

serial port is connected with receive signal (RxD) of serial interface of GSM Modem.

When you want to use the MAX232 you have to connect the RX to the TX of the

device, and the TX of the MAX232 to the RX of the device.

The only way to make the MAX works, the lines between the device and the MAX

must be crossed.



4.2 MICROCONTROLLER – LCD INTERFACING:

Fig4.2.1 [circuit of Interfacing between lcd (16×2) and microcontroller(AT89C52)]

It is very important to keep a track of the working of almost all the automated and semi-

automated devices, be it a washing machine, an autonomous robot or anything else. This is

achieved by displaying their status on a small display module. LCD (Liquid Crystal Display)

screen is such a display module and a 16x2 LCD module is very commonly used. These

modules are replacing seven segments and other multi segment LEDs for these purposes. The

reasons being: LCDs are economical, easily programmable, have no limitation of displaying

special & even custom characters (unlike in seven segments), animations and so on. LCD can

be easily interfaced with a microcontroller to display a message or status of a device. This

topic explains the basics of a 16x2 LCD and how it can be interfaced with AT89C51 to

display a character.



4.3 TESTING AND TROUBLESHOTING:

Problem-1: LCD don't responding.

Solution: Here we find that there is voltage reaches at the lcd and controller,

but grounding was not done properly. Than we implement common grounding

between power supply, controller and LCD.

Problem-2: voltage drop after connecting sensing circuit.

Solution: There is voltage drop approximately 1.5v when we connect sensing

circuit with controller. There is a problem regarding to impedance matching. To

overcome this problem we connect 1k resistor between output of sensing circuit

and controller.



CHAPTER 5:

5.1 APPLICATIONS:

The project is used to transfer the information from the transmitter side to the receiver side

wirelessly. The project is an advance application of GSM based DISPLAY TOOLKIT.

In our project we are basically focussing on the situation where the where the patient(s) and

the doctor are at the distant location and it is quite necessary to give the details about the

patient(s) heartbeat to the doctor. In this type of situation where the information becomes the

indespensable part of the life this project emerges out as best to acknowledge the doctor with

he correct and the fast information.

Besides this if made certain changes in the project, it can also be used as way of

acknowledging the students of the institutes with the fastest mode of information regarding

certain Notices. Again it is the application of GSM BASED DISPLAY TOOLKIT.

Looking into current trend of information transfer in the campus, it is seen that important

notice take time to be displayed in the notice boards. This latency is not expected in most of

the cases and must be avoided.

Also the electronics displays which are currently used are programmable displays which need

to be reprogrammed each time a new notice comes. The process of reprogramming includes

burning the microcontroller again and again. This makes it inefficient for immediate

information transfer, and thus the display board looses its importance.

5.2 CONCLUSION:

This Project which demonstrates an automated patient monitoring system has its own merits

and demerits which are discussed below:

5.2.1 MERITS:

The wireless alert system using WAP notifies physicians of critical results on their Display

(Cellular Phones can also be used as a display).

1. With online recording of medical parameters, the workload of the case providers and the

nursing staff is reduced.



2. The clinical information database contains all data regarding the patients in electronic

form.

3. The patient call switches help emergency situations to be handled quickly.

Future enhancements can be easily implemented with the PLC controller.

5.2.2 DE-MERITS:

1. The heart beat sensor is highly temperature dependent and the dynamic characteristics

change with different levels of ambient light and temperature level.

2. The dual operational amplifier needs a high CMRR and additional narrowband filters are

necessary to attenuate effects of the noise interference.

3. Network Congestion and Noise interference involved, delays the transmission and

reception of the signal, hence delayed observations are obtained.

5.3 FUTURE ENHANCEMENTS:

The entire medical data acquisition could be made wireless and wearable. Such a package

would contain the circuiting for inputs from ECG sensors, EEG sensors, pressure

measurement and pulse rate transducers. This wearable module can transmit the data

continuously over a fiber optic link or through an internet digital radio. The received data can

be stored in separate memory and be processed by a microcontroller. This enhancement will

enable monitoring of patients to be more flexible and strain-free.

In addition to above the following enhancement can also be made:

A graphical LCD can be used to display a graph of the change of heart rate over time.

Sound can be added to the device so that a sound is output each time a pulse is

received.

The maximum and minimum heart rates over a period of time can be displayed.

Serial output can be attached to the device so that the heart rates can be sent to a PC

for further online or offline analysis.



5.4 REFFERENCES:

WWW.SCRIBE.COM

WWW.ENGINEERSGARAGE.COM

WWW.EMBEDED.COM

WWW.ALLDATASHEET.COM

BOOK:

8051-MICROCONTROLLER AND PROGRAMMING-MAZIDI

telemedicine system using gsm wireless network chapter-1

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