This dissertation is on Laser Communication System. That means a part of the optical communications, in which the information or data is transferred from transmitter end to receiver end with the help of an optical source i.e. Laser (Light Amplification by the Stimulated Emission of Radiation). The aims and objectives of this dissertation are quite simple and can be divided into different sections. Mainly, a) Understanding the concepts of communications (optical), b) Experimental requirements and setup and c) Other things like cost, availability and many more. Each section can be further divided to parts to understand the main objective of the report. Following figure will make it clearer.
Figure 1: Aims and Objectives of Laser Communication System
With the help of the above figure we can understand the actual aim of the project. This figure gives us the complete information including all the aspects of the project, from basic concepts to the results. Let's start with the first aim:
Concepts of optical communications: In this part we should know about all the basic concepts of the optical communications. Optical communication is basically transmitting and receiving data or doing communication with the help of light.
Optical fiber: Optical fiber is a very thin fiber of glass which is having a diameter of a human hair. It is the thing in which light travels without any attenuation. But important thing is that optical communication can also be done without optical fiber. In our project we are not using optical fiber.
Sources of light: There are generally two sources of light in optical communication and that are LASER and LED (Light Emitting Diode). According to requirement we choose one from them. We are using Laser as an optical source in our project.
Final decision: we have to take final decision on the basis of what we want to do and what are the requirements of our project. Accordingly we take decision to have optical fiber in it or not or to use which source of light.
Experimental requirements and setup: In this part we will decide that what are the hardware and software requirements for our project? And, how to do setup for our project.
Transmitter setup requirements: This part includes all the requirements for making the transmitter for our project. In Laser communication system we need a Laser, 3 batteries, 2 alligator clips, transformer, connecting wires, mic and a LED.
Receiver setup requirements: As like the transmitter part, it includes all the requirements for making receiver for our project. In our project we need solar cell and a jack which is plugged in speakers.
Setup of Communication system: Both transmitter and receiver are made properly i.e. all the connections are done. And a communication system is ready for testing the successfulness of the project.
Others: This is the third main aim of our project having following objectives. These are also very important objectives which are to be thought of before making of any project.
Cost considerations: While making a project a budget is kept in mind and according to that budget our whole project is made. We always try to make a physically and economically possible project. The cost of project is kept as low as possible. As our Laser communication system is very cheap.
Availability of requirements: Another major issue is kept in mind before making any project and that is availability of the requirements. All the hardware or software required for our project should be easily available. As in our project each and every part required for the whole system is easily available.
Results: The most important part of our project is result. What we have done, and after all the hard work, the only thing which matters is result. The result of our project should be positive. In our case, in Laser communication system the result was positive. Our system was communicating with the help of a laser beam across the room.
Chapter 2
Review of current state of proposed area
2.1 Laser
LASER is a short form of Light Amplification by the Stimulated Emission of Radiation. The concept of laser is that an atom in excited state encounters a photon of same energy that is equal to the gap energy between the excited and ground states of the atom. When this type of photon is encountered, then another photon is emitted which is of the same energy. This phenomenon was first suggested by Albert Einstein in 1916 in a paper proving Plank's law of radiation.
"Laser communications systems are wireless connections through the atmosphere"[1]. The working principle of the Laser communication system is very similar to fiber optic links, but the difference is that the beam is transmitted through free space. While the transmitter and receiver must require line-of-sight conditions, this is the only so called limitation of the laser communication system. As any obstruction between the transmitter and receiver can cause the data loss but they have the benefit of eliminating the need for buried cables and broadcasting rights. Laser communications systems can be easily deployed since they are inexpensive, small, low power and do not require any radio interference stuff to study. The carrier used for the transmission signal is generated by a laser diode. Two parallel beams are needed, one for transmission and one for reception. But the system which is to be implemented in this project is only one way.
2.2 Optical fiber
Before starting with the laser communication system we must also know about the optical fiber communications i.e. the communications with the help of glass fibers because laser communications is a part of optical communications somewhere, as laser communication can be done with and without optical fiber and laser is also a source of light in optical communication with LED (Light emitting diode) [2,4].
This thinking of optical communications with the help of the glass fiber was generated at the time of Alexander Graham Bell [3]. Yet it took many years for its practical implementations as better quality of glass and low cost electronic equipment was invented quite a while after that.
The use of the optical communication technology spread like a fire. And the coaxial copper wire, which were used in early times, were replaced by the optical fibers and a new era of technology emerged called as optical communications technology.
The two technologies electronics communications and optical communications are very much closely related to each other but the principle of operation in both the technologies is different.
2.2.1 Advantages of optical fibers
Data confidentiality i.e. security of the data
Data Integrity i.e. very low loss of data
Long distance communications is possible without involving repeaters, amplifiers and boosters.
Large amount of data can be transmitted.
Optical fibers are immune to EM interference, but not immune to the alpha and the beta radiations.
These optical fibers are not unsafe to use them near the high voltage devices and an area where the earth's potential is different because they have High electrical resistance.
The power requirements of the optical fibers are low as compared to the wires.
The optical fibers are very light in weight, so they are easy to carry.
The speed of the transmitting is very high
2.2.2 Disadvantages of optical fibers
The initial cost and the maintenance cost of the optical fiber is quite high as compared to the wires
To connect two optical fibers we need connectors and splices which are expensive and more difficult to operate than wires.
Optical fibers don't have ability to transmit electrical power for the operation of terminal devices
Extra care is to be taken while handling the optical fibers, as they are very sensitive to physical shocks.
2.3 Sources of light in Optical communication system
There are two main sources of the light in Optical communication systems and they are namely [2]
LED - Light Emitting Diode
LASER- Light Amplification by the Stimulated Emission of Radiation
It totally depends upon the certain factors like application, cost, performance, stability, power and cost, to use which type of source for the system. LED is generally used when them system power requirements is low. As LED make system small in size, reduces its cost, reduces the complexity of the system and also stable with temperature.
LASER is used where the power requirement of the signal is high because if we use LED in high power requirements then the cost of the system will go high. Also in LASER the transmission rate is high, can do long distance communication and more reliable.
Chapter 3
Major Milestones and Deliverables
Following Gantt chart will explain all the Major milestones and deliverables.
Chapter 4
Risk Analysis
As everything in this world have its pros and cons. In every project there are some risks involved. These should be taken care of always because if it is not done then it may ruin our hard work. Similarly there are some risks involved in the Laser communication project. And they are described below.
1.) Hardware failure
The whole project is based upon the hardware. The most common risk is that the system stops working or may not work due to the hardware failure. There are near about ten hardware are used in this project. It is most likely that one of them get damage. Resulting the complete off of the system. It can be cured if we check carefully each and every component before using in the project.
2.) Low quality of received signal
This is another risk involved in the communication system it is the major risk i.e. bad quality of the signal. As we only need the quality of the received signal to be fair enough to extract the complete information from the signal. The probability of getting bad quality of signal totally depends upon the quality of component used and on the connections made between them. This risk can be cured by taking extra care while connections and using good quality of components.
3.) Range problems
This may also happen that our communication system does not work at all even after checking all the components working properly. The thing to be considered is the receiver should in the range of the laser and also should be properly aligned that the laser light falls directly on the panel of solar cell used in the project. Again to remove this error we must take care of it.
4.) Human errors
These human errors include not checking the components carefully, making some loose connections, aiming the laser light out of the range, not using the equipments properly in a good manner, etc. this can happen if an untrained or a non technical person perform the task. This risk can be removed if all is done in a proper manner and procedure.
5.) Dangers
There are some dangers of using these laser lights. As these lasers are of very high power, they can do harm to our skin, to our eyes, to our ears if they fall directly on them. This is the most important thing to be remembered and to be taken care of. As from many experiments it can be seen a paper can catch fire and an inflated balloon burst when it is continuously and directly exposed to the high power lasers. This can happen with some ones carelessness. So an extra care should be taken keeping the ill effects of the laser in mind.
Chapter 5
Resources Needed and Architecture
5.1) Hardware requirements
There are some hardware requirements for our project. They are listed below.
For Transmitter [5]:
Microphone jack: It is used to be inserted in the mic, and to get the mic connected to the whole transmitter system. The mic is used to speak in it. That data said in the mic is transmitted across the room via Laser.
Transformer: It is used to modulate the signal. Amplitude modulation is used in our project as a modulation technique. In our project the amplitude of light i.e. the intensity of light is modulated.
LED: It is used to protect the damage of the laser from the excess current coming from the transformer. This is a Bi polar LED which glows whenever the excess current is detected and that current is used to glow this LED.
Battery: It is used to give the power to the transmitter system. Also the modulated signal is added or subtracted from the battery power and then sent to the Laser.
Laser: It is used to transmit the signal from the transmitter in form of light.
For Receiver [5]:
Solar cell: It is used to receive the laser light transmitted by the transmitter of the system. As the property of a solar cell, the light signal is converted to electrical signal. And this electrical signal is sent to the jack. Jack is used to connect the speaker to receiver system.
Speakers: This speaker produces sound with the help of paper cone effect. The sound is exactly the same which was said in the mic of the transmitter of the system across the room.
5.2) Architectures
a) For Laser communication system
Figure 2 - Laser communication system
The system shown in the figure can send data at very high rate. The system illustrated above is set up to send voice data. The microphone input is fed to the transmitter, where the signal is modulated and then transmitted in free space with the help of a laser [6].
b) For transmitter of the system
Figure 3 - Transmitter for Laser communication system
At the transmitter side, the microphone jack is connected to the mic and something is said in the mic. The transformer modulates the signal and this modulated signal is then added and subtracted from the battery power. Then the resulting signal is send to the laser by which it transfer the signal with varying intensities according to the signal produced. Herein LED is used as a protector to the laser and held parallel to the transformer which only allows the specific amount of current to pass which is required by the laser and rest is consumed by it and it starts glowing [5].
c) For receiver of the system
Figure 4 - Receiver for Laser communication system
At the receiver side, the solar cell receives the light signal i.e. Laser from the transmitter and as the property of the solar cell, when ever the light falls on it , it converts the light signal to electric signal. This electric signal produced is then fed to the speaker and it produces sound by the paper cone effect.
Chapter 6
Ethical, Legal, Professional Issues and Academic Misconduct
Under this heading of ethical, legal, professional issue we will describe about the following few things. But before that I would like to tell you that in this dissertation we don't have to take any approval of any issues. The following things will make you clearer about that.
Data Protection:
Following are some important points for data protection [7]
Personal data must be obtained reasonably and legally. Also some conditions must be applied to it while dealing with personal data, involving ethnicity, political view, religion, health, sexuality or criminal record.
"Personal data processing must be in accordance with the purposes notified by the University to the data protection commissioner- if any 'new processing' is to take place the Data Protection Representative, must be consulted" [7]
Personal data must be kept precise and updated and also not be kept for more than it is required.
Proper security actions must be taken against illegal or not permitted dealing out of personal data.
"Personal data shall not be transferred to a country outside the European Economic Area unless specific exemptions apply" [7].
The whole dissertation is been made by taking care of the Data protection act 1998.
Intellectual Property:
Some important points for this part are:[8]
Copyright: It is the work done by anyone and had recorded it by his name.
Trademark: It is title, logo, slogan or symbol which recognizes the organisation. They are registered at the national or international level with the government body.
Patents: "Patents are grants made by national governments that give the creator of an invention an exclusive right to use, sell or manufacture the invention." [8]
There are some parts in this dissertation which are used and are the copyright of others. But those things are properly referenced at the end of the dissertation.
Computer Misuse:
This Act identifies 3 definite offences: [9]
Unofficial access to computer material (i.e. a program or data).
Unofficial access to a computer system with intention to commit or ease the charge of crime.
Unofficial modification of computer material.
The use of computers and computer networks were totally consistent with the Computer Misuse Act 1990. No rules were broken under this act, while making this dissertation report. None of the above points were violated
Code of Ethics
Code of ethics consists of
IEEE Code:
This dissertation report is made considering the code of ethics of IEEE.
Human adults:
No adult or no workshop was used to do this experiment. The experiment was totally and solely my effort and this dissertation is also been made solely by me.
Human children:
No child was used during this experiment.
Academic Misconduct [10]
The academic misconduct means cheating, plagiarism or any other way of been engaged in by a student with a sight of achieving some grades or marks for himself or herself. Any unjustified way by a student take advantage of the material which is published or unpublished by any one else. In simple words if a student uses work of other people for their profit (grades, marks or making money out of it) without giving the reference of the original owner of material.
While making this dissertation there is no Academic misconduct or Plagiarism as this report is made by me. Any stuff which I took from some published or unpublished sources or from any other source is been properly referenced. I took help from many papers, books and journals and made this dissertation report on Laser Communication System. But all the materials are appropriately referenced at the end of the report. So there is no chance of Academic Misconduct or plagiarism. At the end I would like to say that this report is free from these.
