Wireless Transmission of Audion & Data using Laser

CHAPTER 1

INTRODUCTION

EXTC-SSJCET, ASANGAON 1

CHAPTER 1

INTRODUCTION

Introduction

Our final year project is based on the concept of laser (Light Amplification by

Stimulated Emission of Radiation) for transmitting analog as well as digital signals. We have

used phototransistor to receive the signal at receiver. For voice transmission amplitude

modulation of laser pulse was used to transmit the voice signal. Condenser microphone

converts the voice into electric pulse which was then amplified and transmitted through laser.

Photo detector at receiver detects the laser light and voice was output through loud speaker.

Data transmission is based on pulse width modulation by the use of microcontroller. Different

width of laser pulse was used for different number and character. The microcontrol ler

was used to decode the different characters and the received data is used to turn on devices.

Now a day, information transmission plays a crucial role, where an ever-growing

capacity for communication services is required. The Various communications modes provide us

various routes data channels through which data and information can flow among individuals.

Communication can be between individuals, and even between machines. The flow of

information can be form a human being to equipment and vice versa. Just like the satellite mode

of communication or the optical mode of communication, communication can also occur with

the help of laser.

In this mode of communication, the information is transferred through free space. In the

laser mode of communication; the signals are transmitted from the wireless transmitter to a

wireless receiver without any hindrance or obstruction. Such condition is also called line of sight

condition where the signals are transmitted without any obstruction. Laser diode is the major

carrier in this mode of communication. It does not require any kind of wires and cables and

hence is not a very expensive mode of communication. This mode of communication is also

faster as compared to the other modes and thus is mostly preferred over other types of

communication system.


Two of the major requirements in communication systems are privacy and security. This

project is a proof-of-concept device that transmits an audio and digital signal using a laser beam,

while removing the need for the user to align the beam themselves. Light is already becoming a

popular means of communication, thanks to fiber optics, which can guide optical data much like

a wire transmits current. It might seem impractical, then, to use lasers without a guiding medium

to transmit information. However, in contexts where a physical connection is impossible or

unfeasible, and the need for a focused beam arises, it would seem logical to use laser light. In

particular, free space laser communication has useful applications to military logistics, where

information on the front must be kept limited to friendly ears, and ground-to-air links are

important. We decided to create a simple and inexpensive proof-of-concept to demonstrate the

advantages of this seemingly impractical scheme.

Our project is divided into two distinct sections: audio transmission via hardware, and

alignment control via software. The former can be accomplished once the latter has succeeded,

making the two tasks mutually dependent for overall functionality. This is done by detecting the

light emitted from the receiver’s laser using a phototransistor. The transmitter scans over its free

range until it finds the receiver, at which point the transmitting laser is turned on and the audio

signal is picked up by an array of photodiodes. The details of this process are explored below.

Since our device is a low power setup that produces minimal interfering noise, there are no legal

issues at hand.


CHAPTER 02

LITERATURE SURVEY


CHAPTER 02

LITERATURE SURVEY

2.1 Literature

LASER- LIGHT AMPLIFICATION (BY) STIMULATED EMISSION (OF) RADIATION

Laser based project has been attempted before but data were inputted through

computer. We have tried to simplify it by using 4x3 keypad which provides the complete

set of alphabetical letters. We have also tried to enhance it by implementing voice

communication as well. Laser communication is a modern technology in the world of

communication where bandwidth allocation, power requirement, and dispersion

parameter are becoming major hurdle due to rapid increase in number of user. So considering

these facts we put our interest in this project.

There were various methods for implementing this project but due to scarcity of resources,

components, we decided to use simple modulation and demodulation techniques.

Hence we have designed communication system based on LASER that could be

implemented commercially facilitating the general people in terms of convenient friendly

system. Also it reduces the complexity for communication in some cases where optical fiber

or any wired communication is very difficult and expensive.


2.2 Background Theory

2.2.1 The general principle of laser

Every atom has a certain energy levels, which may be high or low. Once excited by

heating, it goes to high energy level. After certain time in high energy level, it return back to

original energy level, consequently emitting energy in the form of light having energy E=hf.

Incident photon with energy to E2-E1 interacts with an atom in conduction band, causing it

to return to low energy level with the emission of second photon. This photon has same

phase, frequency and polarization as first. This whole phenomenon is known as stimulated

emission, which gives the laser its spectral properties such as narrow spectral width, highly

directed beam and intense light.

Figure.1: Diagram Of Stimulated emission

Einstein demonstrated that for stimulated emission to dominate it was necessary that the

photon radiation density and population density (N2) of the upper energy level must be

increased relative to lower energy lever (N1). Thus when density of atom in higher energy

level is greater than lower energy level (i.e. N2>N1), this phenomenon.


2.3 Pulse Width Modulation

In pulse width modulation the average value of voltage (and current) is controlled by turning

the switch between supply and load on and off at a fast pace. The longer the switch is on

compared to the periods, the higher the power supplied to the load will be. Duty cycle is

expressed in percent, 100% being fully on. The advantage of using the PWM is that power

loss, the product of voltage and current, of the switching device is close to zero. When it is in

switch off condition then there is practically no current and when it is on there will be almost

no voltage drop across the switch. Because of their duty cycle, on/off nature, they can use in

digital controls too.

2.4 Amplitude Modulation

Amplitude modulation (AM) is defined as a process in which the amplitude of the carrier

wave is varied linearly with the message signal [3]. It is a technique used in electronic

communication, most commonly for transmitting information via a radio carrier wave.

The envelope of the amplitude modulated signal embeds the information bearing signal.

The total power of the transmitted signal varies with the modulating signal whereas the carrier

power remains constant.

The main defect of this modulation is that in an AM wave the signal is in the amplitude

variations of the carrier, practically all the natural and man noises consists of electrical

amplitude disturbances. As a receiver cannot dis t inguish between amplitude that

represents noise and that contain the desired signal so reception is generally noisy.


Transmitter

The Transmitter involves a signal processing circuit, and a laser. A laser diode is used to create

the laser signal.

Receiver

This is the "Antenna" of the system. The Receiver involves a Signal Processor and Detector

(Some kind of Photodiode) that will capture and read the incoming laser signal.

2.5 Objectives of Project

To provide simple and cheap wireless communication for larger date rate with less

distortion.

To reduce the complexity for communication in the places where optical fiber or

any wired communication is very difficult and expensive.


CHAPTER 03

PROBLEM DEFINITION


CHAPTER 03

PROBLEM DEFINITION

3.1 BLOCK DIAGRAM

3.1.1Transmitter Section Block Diagram:-

Fig.2: Diagram of Transmitter Section Block


DTMF ENCODER

KEYPAD

AMPLIFIERMICROPHONE

OPTICAL SOURCE

LASER LED BASED

3.1.2 TRASNMITTER SECTION EXPLANATION

Transmitter section is divided is divided into two parts:

Analog (Audio) signal transmission.

Data transmission.

Analog Signal Transmission :

In Audio transmisson, the analog signal is send through microphone/mic uses as

input device, also with the help of 3.5mm audio jack we can transmit the audio

signal from mobile phones, mp3 player etc.

Input analog (audio) signal then goes cocequence steps of amplifification in low

operational amplfier. Amplified signal then tranfered to the laser device for

transmission.

Data Transmission:-

In data transmission, with the help of DTMF keypad we transmit combination

1’s & 0’s throgh laser. The input signal is converted into given specific

voltages and current in DTMF encoder and then the encoded voltage and

current and then tranmitted via laser which is then detected at receiver section

by photodiode.


3.1.3 Receiver Section Block Diagram

Fig.3: Diagram of Receiver Section Block


SPEAKER AMPLIFER

OPTICAL DETECTOR PHOTO TRANSISTOR

BASED

DTMF DECODERMICROCONTROLLERRELAYS

3.1.4 RECEIVER SECTION EXPLANATION

The receiver circuit somewhat resembles the transmitter circuit. Rather than a single

phototransistor, however, it instead uses two photodiodes, which have much larger sensitive

areas compared to the transistor. Since the response of the diodes directly affects the audio

quality, a more complex circuit is called for. The diodes themselves are placed between the two

terminals of an op-amp, whose output voltage is determined by the current that flows through the

diodes.

Using an op-amp instead of biasing the diodes allows us to utilize a near-ideal short-

circuit current. With two diodes in parallel, we effectively double the area upon which we can

receive a signal. After amplifying the signal with a second op-amp, the result is then fed directly

to an audio jack, where the signal can be heard using any compatible device.

The same circuitry is required for data receiver section only difference is that detected

signal is first send to the DTMF decoder for decoding the signal to its original form and then

send it to the microcontroller through which we can control different devices which is connected

at the output of relay normally devices is connected at open position of relay.


CHAPTER 04

APPLIED METHODOLOGY


CHAPTER 04

APPLIED METHODOLOGY

4.1 Circuit Diagram

4.1.1 Transmitter section:-

Fig.4: Diagram of Transmitter Section Ciruit


4.1.2 Receiver Section:-

Fig.5: Diagram of Receiver Section Circuit


4.2 Hardware Required

Transmitter Section:-

Keypad

DTMF Encoder

Low power operational amplifier

Microphone

Laser

Receiver Section:-

Speaker

Amplifier

Photo detector

Decoder

Relay

Microcontroller


Transmitter Section

4.2.1 Keypad Board

Description:-

There are total 12 keys. These are normally open push buttons. When button is normal not

pressed then it gives logic zero. And when button is pressed then it gives logic high +5 Volt 1.

Rows are used as input and columns are used as output. All eight pins are set high at first.

Row 1 is the set low. All four columns are checked if anyone is low. A low would appear if

first column were pressed. If no column was low, row 1 is set high and row 2 is set low.

Again the columns are checked for low. If no key was pressed row 2 was set high and row 3

is set low and process continued. To get the value of the key pressed, as soon as a column is

low for a low row is obtained, 8-bit binary value of the key was returned

Fig.6: Diagram 4x3 Matrixes


Features:-

Ultra-thin design

Adhesive backing

Excellent price/performance ratio

Easy interface to any microcontroller


4.2.2 DTMF Encoder

Description:-

DTMF means Dual Tone Modulation Frequency. This system is intended to transmit

keys pressed on a keyboard through an audio channel such as a telephone line or a radio

connection. Every time a key is pressed two audio frequencies are transmitted: one corresponds

to the column in which the key is in, and the other one corresponds to the row. This encoding

handles a maximum of 4 rows by 4 columns, that means 16 keys (from 0 to 9, *, #, and from A

to D).

This table shows graphically the layout of the keys on the DTMF keyboard with the

corresponding frequencies and the minimum and maximum values for each tone


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Fig.7: Diagram of DTMF Encoding

Features:-

• Full DTMF receiver

• Less than 35mW power consumption

• Uses quartz crystal or ceramic resonators

• Adjustable acquisition and release times


4.2.3 Low Power Dual Operational Amplifiers

Description:-

The symbol indicates an LM358 integrated circuit to 8 feet. One of the particularities of

this integrated is to be designed to operate with a single static power supply that ranges from a

minimum of 3 V to a maximum of 32 V although typically there are stabilizing at levels between

5 V and 15 V. In fact, while most of the integrated circuits containing the operational needs two

power supplies, one positive and one negative, the LM358 can be connected to the positive

power only while the negative supply is replaced by the mass.

Application areas include transducer amplifiers, dc gain blocks and all the conventional op-

amp circuits which now can be more easily implemented in single power supply systems.

Fig.8: Diagram of Operational Amplifiers


Features:-

Wide bandwidth 1.1mhz

Very low supply current (500μa) .

Low input offset voltage: 2mv

Low input offset current: 2na


4.2.4 Microphone

Description:-

A microphone is a electric transducer or sensor that converts sound into an electrical

signal. Microphones are used in many applications such as telephones, tape

recorders, karaoke systems, hearing aids, motion picture production, live and recorded audio

engineering and television broadcasting and in computers for recording voice, speech.

Sometimes other characteristics such as diaphragm size, intended use or orientation of the

principal sound input to the principal axis (end- or side-address) of the microphone are used to

describe the phone.

Fig.9: Diagram of Microphone or Mic


4.2.5 LASER

Description:-

Laser is safe design, use and implementation of lasers to minimize the risk of laser

accidents, especially those involving eye injuries. Since even relatively small amounts of laser

light can lead to permanent eye injuries, the sale and usage of lasers is typically subject to

government regulations.

Moderate and high-power lasers are potentially hazardous because they can burn the retina of the

eye, or even the skin. To control the risk of injury, various specifications, for example ANSI

Z136 in the US and IEC 60825 internationally, define "classes" of laser depending on their

power and wavelength. These regulations also prescribe required safety measures, such as

labeling lasers with specific warnings, and wearing laser safety goggles when operating lasers.

Laser Classes:-

Class I

Class II

Class II a

Class III a

Class III b

Class IV


Class I

This can be either because of a low output power (in which case eye damage is impossible

even after hours of exposure)

Class I lasers is inherently safe.

No possibility of eye damage.

In CD players or laser printers.

Class II

The blink reflex of the human eye (aversion response) will prevent eye damage, unless the

person deliberately stares into the beam for an extended period.

This class includes only lasers that emit visible light.

Most laser pointers are in this category.

Class II a

In Class II a, region in the low-power end of Class II where the laser requires in excess of

1000 seconds of continuous viewing to produce a burn to the retina.

Commercial laser scanners are in this subclass.


Class III a

Lasers in this class are mostly dangerous in combination with optical instruments though

even without optical instrument enhancement direct contact with the eye for over two

minutes may cause serious damage to the retina.

The device is not labeled with a "caution" warning label; otherwise a "danger" warning

label is required.

Many laser sights for firearms and laser pointers are in this category.

Class III b

Lasers in this class may cause damage if the beam enters the eye directly. Lasers in this

category can cause permanent eye damage with exposures of 1/100th of a second or less

depending on the strength of the laser.

Protective eyewear is recommended when direct beam viewing of Class III b lasers may

occur.

Class IV

In the beam and may cause severe, permanent damage to eye or skin.

Many industrial, scientific, military and medical lasers are in this category.


Fig.10: Diagram of Laser Pointer


Receiver Section

4.2.6 Microcontroller

Description:-

Used for information gathering from mic & keypad, encode the data & pass it to the Decoder to

output at relay speaker. Microcontroller (sometimes abbreviated µC, uC or MCU) is a small

computer on a single integrated circuit containing a processor core, memory, and programmable

input/output peripherals. AT89C51 is an 8-bit microcontroller and belongs to Atmel's 8051

family. ATMEL 89C51 has 4KB of Flash programmable and erasable read only memory

(PEROM) and 128 bytes of RAM. It can be erased and program to a maximum of 1000 times.

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 AT89C51 is a powerful microcomputer which provides highly-

flexible and cost-effective solution to many embedded control applications.


Fig.11: Diagram of Pin structure 89C51


Features:-

4K Bytes of In-System Reprogrammable Flash Memory.

Three-level Program Memory Lock

128 x 8-bit Internal RAM

32 Programmable I/O Lines

Two 16-bit Timer/Counters

Six Interrupt Sources

Programmable Serial Channel

Low-power Idle and Power-down Modes

Tab.1: Table for Port Pin Structure


4.2.7 Loudspeaker

Description:- A loudspeaker (or "speaker") is an electroacoustic transducer that produces sound in

response to an electrical audio signal input. Non-electrical loudspeakers were developed as

accessories to telephone systems, but electronic amplification by vacuum tube made

loudspeakers more generally useful.

The most common form of loudspeaker uses a paper cone supporting a voice coil

electromagnet acting on a permanent magnet, but many other types exist. Where high fidelity

reproduction of sound is required, multiple loudspeakers may be used, each reproducing a part of

the audible frequency range. Miniature loudspeakers are found in devices such as radio and TV

receivers, and many forms of music players. Larger loudspeaker systems are used for music,

sound reinforcement in theatres and concerts, and in public address systems.

Fig.12: Diagram of Loudspeaker


4.2.8 Relay

Description:-A relay is an electrically operated switch. Many relays use an electromagnet to operate a

switching mechanism mechanically, but other operating principles are also used. Relays are used

where it is necessary to control a circuit by a low-power signal (with complete electrical isolation

between control and controlled circuits), or where several circuits must be controlled by one

signal. The first relays were used in long distance telegraph circuits, repeating the signal coming

in from one circuit and re-transmitting it to another.. Solid-state relays control power circuits

with no moving parts, instead using a semiconductor device to perform switching. Relays with

calibrated operating characteristics and sometimes multiple operating coils are used to protect

electrical circuits from overload or faults, in modern electric power systems these functions are

performed by digital instruments still called “protective relays.” In our project we are using relay

G5LE

Fig.13: Diagram of Relay


Feature:-

1 Subminiature “sugar cube” relay

2 Contact ratings of 10 A

3 Withstands impulses of up to 4,500 V

4 Ideal for applications in security equipment, household electrical appliances, garage

door openers, and audio equipment.


4.2.9 Photodiode

Description:- The BPW32 is an opto-electronic integrated circuit containing a photodiode and trans

impedance trans impedance amplifier consists of a precision FET input op amp and an on-chip

metal film resistor. The integrated combination of photodiode eliminates the problems

commonly encountered in discrete designs such as leakage current errors, noise pick-up and gain

peaking due to stray capacitance.

Fig.14: Diagram of Photodiode

Features:-

Photodiode Size: 0.090 x 0.090 inch

Improved UV Response

Low Dark Errors: 2mV

Bandwidth: 4kHz

Wide Supply Range: 2.25 to 18V


4.3 Software

4.3.1 Flow chart:-

Data transfer


START

Configure the port

Transmission of signal

Modulates the voice signal / data signal

using laser light and transmit the signal

Amplifes the voice signal

Detect voice signal using photo transisitor

Pass the voice to the loud speaker

STOP

STOP

Pass the decoded signal to output device

from relay

Send to

microcontroller

Detect data from photo transistor

Decode with help of DTMF decoder

Amplifies the voice signal

Get audio signal from 3.5jack or mic

Encode with help of DTMF encoder

Get data from keypad

YESNO

YES

NO

Audio transfer

4.3.2 Algorithm

Algorithm for Voice Communication:

First the input voice is taken through condenser microphone.

The voice signal is amplified through preamplifier phase.

Then, the signal is transmitted through laser light.

The phototransistor at receiving side converts the signal into electrical signal.

The electrical signal is passed through two transistor amplifier phases.

Then audio amplifier amplifies the signal and drive speaker to generate voice output.

Algorithm for Data Communication:

First the data are inputted through keypad.

These data is then encoded by the DTMF encoder and gives the corresponding

pulse duration to laser via one of the pins.

The phototransistor detects the laser light incident on it and converts it into

electrical signal.

These electrical signals are fed to microcontroller which sends data to relay.


4.4 PROGRAM

#include<reg51.h>

sbit DecoderOp1 = P1^0;




sbit Relay1 = P0^0;

sbit Relay2 = P0^1;

sbit Relay3 = P0^2;

sbit Relay4 = P0^3;

void main()

{

P1=0xFF;

P0=0;

while(1)

{

if(DecoderOp1 == 1 && DecoderOp2 == 1 && DecoderOp3 == 0 && DecoderOp4 == 0 ) /// Pressed '1'

{

Relay1=1;

}



{

Relay1=0;

}

/* if(DecoderOp1 == 0 && DecoderOp2 == 1 && DecoderOp3 == 0 && DecoderOp4 == 0 ) /// Pressed '4'

{

Relay2=1;

}


{

Relay2=0;

}


{

Relay3=1;

}


{

Relay3=0;

}

if(DecoderOp1 == 1 && DecoderOp2 == 0 && DecoderOp3 == 1 && DecoderOp4 == 1 ) /// Pressed '*'

{


Relay4=1;

}


{

Relay4=0;

}


{

Relay1=0; Relay2=0; Relay3=0; Relay4=0;

}


{

Relay1=1; Relay2=1; Relay3=1; Relay4=1;

}

}

}


CHAPTER 05

PCB FABRICATION


CHAPTER 05

PCB FABRICATION

5.1 Developing The PCBDeveloping The PCBNow that the Circuit Diagrams are ready, we can use them to develop the Printed Circuit Boards.

1 The first step is to design the

schematics in a PCB Layout Editor

such as EAGLE. After the

schematic is entered, the PCB

layout program is used to place the

parts on the board and route the

copper traces.

Fig.15: Diagram of Schematic PCB Layout

2 After the first few parts are

mounted, the "rats nest" begins to

clear up. If you're lucky, you get a

PCB that requires no external

jumper wires.

Fig16: Diagram of Printed Circuit


3 When the layout is done, the board

layers are printed onto special toner

transfer paper with a laser printer.

This board "image" is transferred to

the bare copper board with a

laminating machine, or a hot clothes

iron.

Fig.17: Diagram of Laser Printer

4 After laminating, the board with the

paper stuck to it is soaked to

remove the paper, leaving only the

toner behind

Fig.18: Diagram of PCB Solution


5 To the right is a photo of the raw

copper board with toner

remaining, after the transfer paper

has been soaked off

Fig.19: Diagram of Raw Copper Board

6 Inside the etch tank, two aquarium

pumps circulate etchant

(Ammonium Per sulfate) over the

copper boards while two aquarium

heaters keep the solution at

110F.This process can take

anywhere from 10-30 minutes

depending on the freshness of the

solution and thickness of the

copper.

Fig.20: Diagram of Etch Tank


7 After etching, the toner is removed

with solvent and the board is tinned

using a soldering iron and a small

piece of tinned solder wick. Tinning

isn't absolutely necessary but it

improves the appearance of the

board, and prevents the copper from

oxidizing before it's time to solder

the parts to the board.

Fig.21: Diagram of Toner Removed

8 At this point, holes are drilled for

any leaded components and

mounting holes.

Fig.22: Diagram of PCB Drilling

9 Here is the completed board ready

to be populated

Fig.23 Diagram of Final PCB Layout


CHAPTER 06

PCB IMPLEMENTATION


CHAPTER 06

PCB IMPLEMENTATION

6.1 PCB Layout

6.1.1 Transmitter PCB Layout:-

Fig.24: Diagram of Transmitter Bottom Fig.25: Diagram of Transmitter top


6.1.2 Receiver PCB Layout:-

Fig.26: Diagram of Receiver Bottom Fig.27: Diagram of Receiver Top


CHAPTER 07

APPLICATIONS AND FUTURE SCOPE


CHAPTER 07

APPLICATIONS AND FUTURE SCOPE

7.1 Applications

In arenas & concerts it would use as temporary set up without caballing material.

In internet, it is use as fast medium for transmission of data packets.

Military application.

Severe weather conditions will be bypassed by Laser Light’s meshed inter-satellite rerouting

capabilities. Laser Light considers this approach a significant refinement, enabling it to

dynamically identify and deliver traffic to Light way ground access nodes with interconnected

fiber access and hence is it is used for weather forecast.


7.2 Future Scope

In future, there is possibility by this audio transmission of laser we can connect the all musical

concerts worldwide using the same technology.

Multiple voice, data, picture, video can be multiplied simultaneously to perform

communication using Multiplexer.

A more power laser can be used to increase the range of communication.

Laser can be replaced by IR laser that can’t be visible by bare eye


7.3 Advantages

Unlike radio systems, laser communications is an optical technology that does not require

spectrum licensing or frequency coordination.

Optical satellite systems are not susceptible to interference from one to another system or

equipment since the point-to-point laser signal is extremely difficult to intercept.

Lighter than equivalent copper wires or cables. Make the system as cost effective as possible.

Wider bandwidth for data transmission, Very fast communication speed more than 1GBps.

This means that it does not fall under the regulations of the International Telecommunication

Union (ITU) in terms of frequency allocation and spectrum regulations.

The new medium of information transfer higher quality.

Alternative communication systems during disasters (PSTN ).Less noise, inexpensive, power

efficient both transmitter and receiver


7.4 Disadvantages

Direct line-of-sight.

Rain, smoke, fog, glass etc-reduce the light intensitywhich affect the overall project.

Obstacle comming in between the Transimeter and receiver.

For longer distance communication high power laser is required which is costly.


CHAPTER 08

RESULTS


CHAPTER 8

RESULTS

Result

Thus we have achieved the following results:

Transmitting equipment that is biologically safe and consumes minimum of bandwidth, when

dealing with audio transmission.

Generally, the AUDIO is generally up to its mark.

A system that is immune to external noise.

Thus our project gives wireless technique to offer security to valuable commodities


Chapter 09

Conclusions


Chapter 09

Conclusions

Conclusions

Our final product nearly met our initial expectations. We didn’t expect the audio quality to be as

good as it was given the relative ease of designing the circuits, but the unreliable nature of the

alignment was something we hadn’t anticipated, and didn’t have a solution readily available for.

As for hardware, we found that considering every device as if the operating conditions were ideal

cost us time and money that could have otherwise been more productive. Not considering the

area of the phototransistors, for example, was an avoidable oversight. Additionally, with more

time and an expanded budget we could deal with the alignment issue and build on it: with more

investment in optical hardware the lasers could be secured with more precision.


REFERENCES


REFERENCES

[1] Author-Mazidi and Ayala Kenneth. Book-Microcontroller architecture,

programming and applications. Publication- Penram Publication. Edition-5th 20

[2] Author- Dr. Roy Chaudhari. Book- Linear integration circuits.

Publication-New age international. Edition- 3rd 2007.

Web site:

www.google.com

www.alldatasheet.com

www.howstuffworks.com


APPENDIX


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Wireless Transmission of Audion & Data using Laser

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