Infrared Wireless Headphones

A Minor Project Report

submitted in partial fulfilment of the

requirement for the award of the degree

of

Bachelor of Technology

in

Electronics & Communication Engineering

(Under the guidance of Er. Krishan Kumar)

By: Karan Sharma (07416) Piyush Yadav (07425) Kumar Rajeev Ranjan (07438)

DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING

NATIONAL INSTITUTE OF TECHNOLOGY

HAMIRPUR-177005, HP (INDIA)

“April 2010”

2

CERTIFICATE

We hereby certify that the work which is being presented in the Minor Project Report entitled

―Wireless Infrared Headphones‖ is in partial fulfilment of the requirements for the award

of the B.Tech. and submitted to the Department of Electronics & Communication

Engineering of National Institute of Technology, Hamirpur is an authentic record of our own

work carried out during a period from Jan 2010 to April 2010 under the supervision of Er.

Krishan Kumar (Faculty, ECED NIT Hamirpur). The matter presented in this thesis has not

been submitted by me for the award of any other degree elsewhere.

Karan Sharma Piyush Yadav Kumar Rajeev Ranjan

(07416) (07425) (07438)

This is to certify that the above statement made by the candidates is correct to the best of my

knowledge.

Date: April 25, 2010.

Dr. Vinod Kapoor Er. Ashwani Kumar Mr. Krishan Kumar

HEAD Sen. Lecturer E&CED E&CE Department

E&CE Department (Project Co-ordinator) (Project Guide)

3

ACKNOWLEDGEMENT

We are very grateful to Er. Krishan Kumar, our project guide whose constant support and

encouragement has helped us in conceiving the project and realise it today. We are also

grateful to other faculty members of our Electronics Department who have constantly

watched us and guided us especially Dr. Rajeevan Chandel.

We extend our gratitude to Dr. Vinod Kapoor who has created such a wonderful learning

ambience in the department. We are also thankful to staff members of Electronics and

Communication Engineering Department who have given us their valuable guidance in

making this project a successful one.

4

CONTENTS

Page No.

Abstract

1. Overview

6-10

1.1 Introduction

1.2 Technology Overview

1.3 Evolution of Infrared Communication System

1.4 System configuration of Wireless IR Communication

Systems

6

7

8

10

2. Objectives

11

3. Infrared Systems

12-14

3.1 Properties

3.2 Advantages

3.3 Disadvantages

3.4 Applications

12

13

14

14

4. Hardware description

4.1 Design Considerations

4.2 Block Diagram

4.3 Circuit Diagram

4.4 Working

4.5 Power Consideration

16-20

16

17

18

19

20

5. Simulation, Analysis and Amendments

5.1 Simulation

5.3 Observations

5.4 Amendments

21

22

22

22

6. Results and Inference

23

7. References

24

8. Appendix

8.1 List of figures

8.2 Datasheet

Photo Transistor

Infrared Diode

Transistor BC 547

OP-AMP 741-C

LM 386

25

26-44

5

Abstract

Infrared Rays form a part of the electromagnetic spectrum which has a wavelength ranging

from 0.7 to 400 um. It is known widely for its heating effects and the role it plays in

atmosphere. Infrared rays find large applications in electronic and wireless applications due

to certain advantages provided by its inherent properties.

In the past few decades, an unprecedented demand for wireless technologies has been taking

place. Mobiles, Laptops, assistants (PDAs), and mobile phones, to name just a few examples,

are becoming part of the everyday life of a growing number of devices that communicate

wirelessly. Radio and infrared (IR) are currently the main parts of the electromagnetic

spectrum used to transmit information wirelessly. IR is becoming more popular every day

and it is being preferred due to its inherent advantages like low power requirements, security,

effective short distance communication as compared to its Radio counterpart.

In this project we aim to design and build a hardware model of IR transmitter and receiver

that is capable of communicating data over a short range. The device we plan to build could

be integrated with the digital devices to transmit signals in the audio frequency range of

20Hz to 20000Hz over a range of 2 to 3 metres. Also we aim to study the properties of the IR

communication in terms of the range acquired and the power requirements of the system.

6

Introduction

In the past few decades, a demand for wireless technologies has tremendously increased.

Both industrial and private customers are demanding products -for a wide range of

applications- that incorporate wireless features, which allow them to exchange, receive, or

transmit information without the inconvenience of having to be fixed to any particular

location.

The benefits of wireless technologies are not limited to user convenience- in terms of

mobility — and flexibility in the placement of terminals. Significant reductions in cost and

time also can be achieved, in a number of applications, using wireless solutions.

Reconfiguring computer terminals or microcontroller systems (in places such as laboratories,

conference rooms, offices, hospitals, production floors, or educational institutions), for

instance, can be done relatively cheaply and quickly with wireless networks. Maintaining and

reconfiguring wired networks, on the other hand, is usually carried out in more expensive,

time-consuming, and complicated ways (especially in situations where cables are grounded or

installed in inaccessible places). Furthermore, cables are susceptible to damage, which means

potential disruption to the network operation. Radio and infrared (IR) are currently the main

parts of the electromagnetic spectrum used to transmit information wirelessly. By the term

―radio‖ we refer to the radiofrequency and microwave parts of the spectrum, and ―IR‖ to the

near-infrared part of it.

In homes, some member prefers to watch television while others don’t. It becomes difficult

for younger member to go against the will of elder, especially in Indian scenario, so younger

have to suffer in most of cases. Wired headphones do not give flexibility for mobility and

more users to accommodate (usually due to predefined design), so wireless headphones are

required to meet the requirement. We in this project intend to make wireless system using

Infrared technology, so as to counter this problem. Thus, Infrared cordless headphones would

be used for watching TV and movies with full enjoyment but without disturbing the peace at

home.

7

1.2 Technology Overview

Radio and infrared (IR) are currently the main parts of the electromagnetic spectrum used to

transmit information wirelessly. By the term ―radio‖ we refer to the radiofrequency and

microwave parts of the spectrum, and ―IR‖ to the near-infrared part of it. Infrared rays have a

wavelength ranging from 0.7 to 400 µm which corresponds to a frequency ranging from 1

THz to 400 THz.

Most of today’s wireless communication is based on radio frequency but IR frequency is also

being used and is becoming popular these days (due to its inherent advantages) over its radio

counterpart for a number of applications.

From a spectrum management point of view, for example, IR offers potentially huge

bandwidths that are currently unregulated worldwide. The radio part of the spectrum, on the

other hand, gets more congested every year, and the allocation of radio frequencies is

increasingly difficult and expensive. Moreover, due the fact that the authorities that regulate

the allocation of radio frequencies vary from one country to another so device are to be

modelled accordingly in different country.

Another advantage of IR over radio is its immunity to electromagnetic interference (EMI).

This makes IR the preferred option in environments where interference must be minimized or

eliminated. In addition, IR does not interfere with and is not affected by radio frequencies,

which is particularly relevant in hospitals, as explained in a number of published articles in

the area.

IR also presents advantages over radio in terms of security. Because IR radiation behaves like

visible light, it does not penetrate walls, which means that the room where the energy is

generated encloses the emitted signal completely (assuming there are no windows or

transparent barriers between rooms). This prevents the transmitted information from being

detected outside and implies intrinsic security against eavesdropping. Further advantages of

IR over radio include the low cost, the small size, and the limited power consumption of IR

components.

Despite the advantages presented by the infrared medium, IR is not without its drawbacks.

Infrared wireless links are susceptible to blocking from persons and objects, which can result

in the attenuation of the received signal. In addition, wireless IR systems generally operate in

environments where other sources of illumination are present. If this background illumination

has part of its energy in the spectral region used by wireless IR transmitters and receivers, it

introduces noise in the photodetector, which limits the range of the system.

Moreover, optical wireless systems are also affected by the high attenuation suffered by the

IR signal when transmitted through air, and by atmospheric phenomena such as fog and snow

that further reduce the range of the system and deteriorate the quality of the transmission

when operating outdoors [3]

8

1.3 Evolution of Infrared Communication Systems

Optical wireless communication systems have experienced a huge development since the late

1970s when IR was first proposed as an alternative way (to radio) to connect computer

networks without cables.

IBM was one of the first organizations to work on wireless IR networks. The first reports on

IBM’s experimental work were published between 1978 and 1981. They have described a

duplex IR link that achieved a bit rate of 64 kbps using PSK and a carrier frequency of 256

kHz [4]

In 1983, Minami et al. from Fujitsu described a full-duplex LOS system that operated under

the same principles as the network described by Gfeller. That system consisted of an optical

satellite attached to the ceiling and connected to a network node via a cable, and of a number

of computer terminals that communicated to the server via the optical satellite. It operated at

19.2 kbps (over 10 m) with an error rate of 10−6 when working under fluorescent

illumination. By 1985, the Fujitsu team had managed to improve the data rate of its system to

48 kbps, as reported by Takahashi and Touge. [A]

In the same year (1985), researchers from two other companies (Hitachi and HP Labs)

presented their own work in the area of wireless IR communications. In the case of Hitachi,

Nakata et al. reported a directed-LOS network system that replaced the optical satellite on the

ceiling with an optical reflector. This system achieved a data rate of up to 1 Mbps with a BER

of less than 10−7 for a distance of 5 m.[ 4]

In 1987, AT&T Bell presented their work on optical wireless communications. They reported

a directed-LOS system that operated at 45 Mbps over a wavelength of 800 nm. [5]

More recently, Showa Electric reported a 100-Mbps short-range IR wireless transceiver that

operated over a maximum range of 20 m and used LEDs for the transmitter and avalanche

photodetector (APDs) for the receiver. Another system, proposed by Singh et al. in 2004 [24],

was based on the idea of a base station attached to the ceiling and connected to the network

via a backbone. The proposed network operated at 100 Mbps and was based on DPPM with

carrier sense multiple access with collision detection (CSMA/CD) for the Media Access

Control (MAC) protocol.

9

Fig 1.3.1 Chronology of indoor optical wireless communication research

10

1.4 System Configurations of Wireless IR Communication Systems

Optical wireless systems for indoor and outdoor use can be arranged in a number of configurations

depending on the specific requirements of a system. In general, the topologies used for indoor optical

wireless communication systems are classified according to two parameters: (1) the existence of an

unobstructed path between the transmitter and the receiver (LOS – non-LOS), and (2) the degree of

directionality of the transmitter, the receiver, or both (directed, non-directed, or hybrid).

Fig. 1.4.1 Different configurations of wireless IR links. The dotted lines represent the different FOVs

11

2. OBJECTIVE

The objective of the project is to design an efficient infrared transmitter-receiver system that

would be capable of transmitting Infrared electromagnetic signals in the audio frequency

range of 20Hz to 20KHz over a range of 2 to 3 metres. The device would be used in

conjunction with the multimedia devices, Computers and Laptops to transmit music from one

place to a pair of cordless headphones by employing the principles of wireless infrared

communication without any degradation in the quality of the music. Also we intend to study

the properties of the system in terms of the range and the power requirements.

Special emphasis is being laid into the communication of the music signals over a large range

and to study the degradation of the signal over a range. Also measures are being taken and a

study is being done to increase the angular range and the linear range of the system. The

objective at end is to obtain a low cost effective IR system ready for marketing purpose.

12

3.1 Properties of Infrared System:

Infrared radiation (IR) is electromagnetic radiation with a wavelength between 0.7 and 300

micrometres, which equates to a frequency range between approximately 1 and 430 THz. Its

wavelength is longer (and the frequency lower) than that of visible light, but the wavelength is

shorter (and the frequency higher) than that of terahertz radiation microwaves.

Fig. 3.1.1 Infrared Spectrum

Infrared Radiation behaves similar to the visible light, so it exhibits all the properties that light does

such as

a) Reflection

b) Refraction

c) Diffraction

d) Diffusion

Attenuation

Atmospheric attenuation is defined as the process whereby some or all of the energy of an

electromagnetic wave is lost (absorbed and/or scattered) when traversing the atmosphere.

Absorption

Absorption, in the context of electromagnetic waves and light, is defined as the process of

conversion of the energy of a photon to internal energy, when electromagnetic radiation is captured

by matter. When particles in the atmosphere absorb light, this absorption provokes a transition (or

excitation) in the particle’s molecules from a lower energy level to a higher one.

Scattering

Scattering is defined as the dispersal of a beam of particles or of radiation into a range of directions

as a result of physical interactions. When a particle intercepts an electromagnetic wave, part of the

wave’s energy is removed by the particle and re-radiated into a solid angle centered at it. The

scattered light is polarized, and of the same wavelength as the incident wavelength, which means

that there is no loss of energy to the particle.

13

3.2 Advantages over RF

a) Wider and Unregulated Spectrum

From a spectrum management point of view, for example, IR offers potentially huge

bandwidths that are currently unregulated worldwide. The radio part of the spectrum, on the

other hand, gets more congested every year, and the allocation of radio frequencies is

increasingly difficult and expensive. Moreover, due the fact that the authorities that regulate

the allocation of radio frequencies vary from one country to another. Device needs to be

modelled accordingly for different country so as to avoid a potential risk of system or product

incompatibility in different geographical locations.

b) High noise immunity: Another advantage of IR over radio is its immunity to electromagnetic interference (EMI).

This makes IR the preferred option in environments where interference must be minimized or

eliminated. In addition, IR does not interfere with and is not affected by radio frequencies,

which is particularly relevant in hospitals, as explained in a number of published articles in

the area.

c) Higher security:

IR also presents advantages over radio in terms of security. Because IR radiation behaves like

visible light, it does not penetrate walls, which means that the room where the energy is

generated encloses the emitted signal completely (assuming there are no windows or

transparent barriers between rooms). This prevents the transmitted information from being

detected outside and implies intrinsic security against eavesdropping. In addition, IR offers

the possibility of rapid wireless deployment and the flexibility of establishing temporary

communication links.

Further advantages of IR over radio include the

d) low cost,

e) the small size (Portable) and

f) the limited power consumption.

This is explained by the fact that wireless IR communication systems make use of the same

opto-electronic devices that have been developed and improved over the past decades for

optical fiber communications and other applications. One such component is the light-

emitting diode (LED), which, due to its now faster response times, high radiant output power,

and improved efficiency, is becoming the preferred option for short-distance optical wireless

applications.

14

3.3 Disadvantages:

a) Direct line of sight communication

Optical wireless links are susceptible to blocking from persons and objects, which can result

in the attenuation of the received signal or in the disruption of the link (depending on the

configuration of the system).That is ;the Wireless IR systems operate only in direct line of

sight communication.

b) Shorter Range

Wireless IR systems generally operate in environments where other sources of

illumination are present. This background illumination has part of its energy in the

spectral region used by wireless IR transmitters and receivers, and introduces noise

in the photodetector, which limits the range of the system.

Moreover, optical wireless systems are also affected by the high attenuation suffered

by the IR signal when transmitted through air, and by atmospheric phenomena such as

fog and snow that further reduce the range of the system and deteriorate the quality of

the transmission when operating outdoors.

c) Restrictions to the emitted optical power due to eye safety.

3.4 Application:

a) Infrared filter

Infrared (transmitting/passing) filters can be made from many different materials. One type is

made of polysulfone plastic that blocks over 99% of the visible light spectrum from ―white‖

light sources such as incandescent filament bulbs. Infrared filters allow a maximum of

infrared output while maintaining extreme covertness. Currently in use around the world,

infrared filters are used in Military, Law Enforcement, Industrial and Commercial

applications.

Active-infrared night vision: the camera illuminates the scene at infrared wavelengths

invisible to the human eye. Despite a dark back-lit scene, active-infrared night vision delivers

identifying details, as seen on the display monitor.

b) Thermography

Infrared radiation can be used to remotely determine the temperature of objects (if the

emissivity is known). This is termed thermography, or in the case of very hot objects in the

NIR or visible it is termed pyrometry. Thermography (thermal imaging) is mainly used in

military and industrial applications but the technology is reaching the public market in the

form of infrared cameras on cars due to the massively reduced production costs.

15

Thermographic cameras detect radiation in the infrared range of the electromagnetic

spectrum (roughly 900–14,000 nanometers or 0.9–14 µm) and produce images of that

radiation. Since infrared radiation is emitted by all objects based on their temperatures,

according to the black body radiation law, thermography makes it possible to "see" one's

environment with or without visible illumination. The amount of radiation emitted by an

object increases with temperature, therefore thermography allows one to see variations in

temperature .

c) Tracking: Infrared homing

Infrared tracking, also known as infrared homing, refers to a passive missile guidance system

which uses the emission from a target of electromagnetic radiation in the infrared part of the

spectrum to track it. Missiles which use infrared seeking are often referred to as "heat-

seekers", since infrared (IR) is just below the visible spectrum of light in frequency and is

radiated strongly by hot bodies.

d) Infrared heating

Infrared radiation can be used as a deliberate heating source. For example it is used in

infrared saunas to heat the occupants, and also to remove ice from the wings of aircraft (de-

icing). FIR is also gaining popularity as a safe method of natural health care & physiotherapy.

Far infrared thermometric therapy garments use thermal technology to provide compressive

support and healing warmth to assist symptom control for arthritis, injury & pain. Infrared

can be used in cooking and heating food as it predominantly heats the opaque, absorbent

objects, rather than the air around them.

e) Communications

IR data transmission is also employed in short-range communication among computer

peripherals and personal digital assistants. These devices usually conform to standards

published by IrDA, the Infrared Data Association. Remote controls and IrDA devices use

infrared light-emitting diodes (LEDs) to emit infrared radiation which is focused by a plastic

lens into a narrow beam. The beam is modulated, i.e. switched on and off, to encode the data.

The receiver uses a silicon photodiode to convert the infrared radiation to an electric current.

It responds only to the rapidly pulsing signal created by the transmitter, and filters out slowly

changing infrared radiation from ambient light. Infrared communications are useful for

indoor use in areas of high population density. IR does not penetrate walls and so does not

interfere with other devices in adjoining rooms. Infrared is the most common way for remote

controls to command appliances.

f) Spectroscopy

Infrared vibrational spectroscopy (see also near infrared spectroscopy) is a technique which

can be used to identify molecules by analysis of their constituent bonds. Each chemical bond

in a molecule vibrates at a frequency which is characteristic of that bond. A group of atoms in

a molecule (e.g. CH2) may have multiple modes of oscillation caused by the stretching and

16

bending motions of the group as a whole. If an oscillation leads to a change in dipole in the

molecule, then it will absorb a photon which has the same frequency. The vibrational

frequencies of most molecules correspond to the frequencies of infrared light. Typically, the

technique is used to study organic compounds using light radiation from 4000–400 cm−1, the

mid-infrared. A spectrum of all the frequencies of absorption in a sample is recorded. This

can be used to gain information about the sample composition in terms of chemical groups

present and also its purity (for example a wet sample will show a broad O-H absorption

around 3200 cm−1).

4.1 Design Consideration:

Optical fiber technology has undergone major developments in the past decades; and as

wireless IR communication systems use some of the same components employed in optical

fiber systems, wireless IR systems benefit from mature and efficient devices that are available

at a relatively low cost The selection of the opto-electronic components for the transmitter

and the receiver is generally done according to the configuration desired for a system.

Directed topologies require directed sources and detectors, while non-directed links require

wide emission beams and wide FOVs.

One of the things that can be observed from the information of different systems developed

so far is that wireless IR communications employs (1) light emitting diodes and (2) laser

diodes for wireless IR transmitters. LEDs present wider emission beams than LDs, which

makes them the preferred option of the indoor non-directed and the hybrid configurations. In

addition, they are generally considered as eye safe, which means that they can be used at

higher emission powers than LDs

Fig. 4.1.1 Channel model from transmitted signal power to generated photocurrent:

(intensity modulation and direct detection)

17

4.2 Block Diagram

Fig. 4.2.1 Block Diagram of system

18

4.3 Circuit Diagram:

Fig.4.3.1 Infrared Transmitter

Fig. 4.3.2 Infrared Receiver

19

4.4 Working Of the circuit:

The circuit essentially can be divided into two major sub circuits:

1. The transmitter circuit 2. The Receiver Circuit

The transmitter Circuit:

The transmitter circuit consists of the two transistor amplifier stage which is used to amplify

the audio signals supplied to the circuit. The audio signal ranges within frequency from 20

Hz to 20,000Hz.The two resistors R1 ,R5 and R2 are used for the dc biasing of the transistor

Q1 which is a BC547A npn transistor having a Base to Emitter Voltage rating of 6.0 V. The

Red LED is used for the biasing of the transistor Q2 which is a SK100 transistor which is a

npn transistor capable of handling high currents. The resistance R4 is used to control the

emitter current The transmitter circuit is provided with a power supply of 9V dc which

drives the circuit. The power is supplied by means of batteries. The LED acts as an indicator

as well. The current from the transistor Q2 is used to drive the two IR LEDs which emit the

modulated IR rays.

The Receiver Circuit

In the receiver circuit, the IR photodiode D1 receives the Infrared rays from the transmitter

circuit and generates a proportionate photo current. The photocurrent is fed into the popular

Op-Amp IC μA741to amplify the signals. The gain of the Op-Amp can be easily controlled

by varying the resistance of the potentiometer. The audio-frequency amplifier IC LM386 is

used to further amplify the signals. The output is provided to the Loudspeaker which

generates the music.

20

4.5 Power and Budget Considerations

The power budget is one of the most important considerations when designing a Wireless

communication system because it defines the battery size and the operation time of portable

units. Power consumption is determined by a number of factors, such as the electronic and

the optical components used, the modulation scheme, the topology, and the emitted power of

a wireless system. The type of technology used also affects power consumption.

IR transceivers present a lower power requirement than their RF counterparts. An optical

wireless transceiver operating at 1 Mbps consumes 150 mW, while a radio LAN transceiver

consumes 1.5 W, which corresponds to a 25 Percent extra drain on the power supply of a

laptop.

The power consumption of a system is strongly affected by the power emitted by the

transmitter. This power should be high enough to cover the desired range of a particular

system, as well as to supply the receiver with sufficient energy.

The power at the receiver is determined by the range of the link, the topology used the

geometry of the room where the system is operating, and the reflective properties of its walls

and ceiling. In addition, the use of an optical collimating element can minimize the power

consumption at the transmitter by transforming an extended source into a concentrated source

with narrow emission angles. When this is the case, care must be taken to comply with eye

safety regulations. The use of collimated sources also allows the use of narrower receivers,

which, due to their directive nature, can present high optical gain increasing the sensitivity of

the receiver and reducing the need for a high transmitted power for a given distance. The use

of angle-diversity receivers and multi-spot transmitters also helps to reduce power

consumption while maintaining wide coverage.

Optical Concentrators and Power Requirements

Another way of improving power consumption is through the use of an optical concentrator

at the receiver. This is possible due to the fact that an optical concentrator improves the

sensitivity of the receiver, which means that a lower emitted power may be required at the

transmitter (for a given range) compared to the same system without a concentrator. To

optimize the power consumption, it is also important to transmit only the relevant

information, to use an effective signal coding, and to perform the required signal processing

at low power if possible.

21

5 Simulation, Analysis and Amendments

5.1 Simulation:

The circuit was simulated by the Circuit Maker Software to obtain the following plots at the

transmitter.

Input Wave

Fig. 5.1.1 Input Waveform

Output at the end of the IR LED.

Fig. 5.1.2 Output waveform at the end of IR LED

22

5.2 Observation:

In order to study the range of the IR Transmitter-Receiver system, we supplied the transmitter

with a sinusoidal signal and observed the output wave form at the DSO. The output received

at the receiver and the DSO was also observed to be sinusoidal for a range of 3 metres. The

quality of the music received was exceptionally good for a range of 1.5 metre after which it

started deteriorating. An Optical Concentrator was then employed at the transmitting LED

side. It was observed that the volume and the quality of the music received were highly

improved.

5.3 Amendments

1. Wider Line of Sight

Infrared Communication is line of sight communication. Due to this if there is an obstruction placed between the transmitter and the receiver then the transfer of the data stops. Improvements to this headphone technology will be provided by the project team, where we will use a lens in front of the LEDs to diffuse the light to provide a wider line of sight for the infrared headphones to catch –thereby reducing chances of losing the signal .

This method of diffusing the infrared beam also means the listener needs no longer to sit directly in front the infrared transmitter which plugs into your TV or other audio source. When it comes to TV/movie watching and untainted enjoyment of the sound infrared cordless headphones have a number of advantages which make them ideal for a comfy relaxing viewing experience.

2. Better Range

Use of power amplifiers and an array of high power LEDs arranged at different angles will be used to increase the range of infrared transmission to cover more area.

3. Use Of Optical Concentrator

By using Optical Concentrator at the Transmitting end, the IR Power gets concentrated and a higher volume of the music and a better quality of music can be obtained.

23

6.1 RESULT:

The IR Cordless headphones were successfully built and a detailed study of the Wireless IR

Communication was carried out. The range of the system was increased by using array of

LEDs. Also optical concentrators were used to improve the power ratings , the amplification

and quality of the music received. Diffusers were also used successfully to increase the

angular range.

6.2 FUTURE WORK

In future we plan to study and work more on the IR systems.The IR systems provide a

potential for future research work for short range communication because of its inherent

advantages.We plan to work on increasing the bit rate transfer of the IR systems so that they

can be used effectively in futurefor faster communication

24

7. Reference:

1. Optical Wireless Communications (IR for Wireless Connectivity) by Roberto

Ramirez-Iniguez, Sevia M. Idrus, Ziran Sun, (ISBN-13:978‑0‑8493‑7209‑4) Taylor

& Francis Group, New York (2008).

2. Farshad Arvin and Khairulmizam Samsudin,Abdul Rahman Ramli, ―A Short-

Range Infrared Communication‖, 2009 International Conference on Signal

Processing Systems. Digital Object Identifier: 10.1109/ICSPS.2009.88

Publication Year: 2009 , Page(s): 454 – 458.

3. JOSEPH M. KAHN, MEMBER, IEEE, AND JOHN R. BARRY "Wireless

Infrared Communications" PROCEEDINGS OF THE IEEE, VOL. 85, NO. 2,

FEBRUARY 1997.

4. F.R. Gfeller, H.R. Muller, and P. Vettiger, Infrared Communication for In-House

Applications, presented at IEEE COMPCON ’78, Washington, D.C., 1978, pp. 132–

138.

5. T.S. Chu and M.J. Gans, High Speed Infrared Local Wireless Communication, in

IEEE Communications Magazine, 25(8), 4–10, 1987.

E-books:

A. O. Takahashi and T. Touge, Optical Wireless Network for Office Communication,

presented at JARECT, 1985, pp. 217–228.

Websites:

1. http://www.wikipedia.org

2. http://howstuffworks.com

25

8. List of figures:

Fig 1.3.1 Chronology of indoor optical wireless communication research

Fig. 1.4.1 Different configurations of wireless IR links. The dotted lines represent the

different FOVs

Fig. 3.1.1 Infrared Spectrum

Fig. 4.1.1 Channel model from transmitted signal power to generated photocurrent: (intensity

modulation and direct detection)

Fig. 4.2.1 Block Diagram of system

Fig.4.3.1 Infrared Transmitter

Fig. 4.3.2 Infrared Receiver

Fig. 5.1.1 Input Waveform

Fig. 5.1.2 Output waveform at the end of IR LED