A novel audio and data signal modulator using visible light for long distance communication

Project Title

A novel audio and data signal modulator using visible light for long distance communication

Project Area of Specialization Information & Communication TechnologyProject Summary

In the past recent years, the number of electronic devices such as smart phones, tablets, sensors, smart household appliances has tremendously increased . Now the users of these devices also need a constant and continuous communication which means that they require an internet connection 24/7 or a high quality media access (wireless). They also need very high data rates to prevent the scarce radio spectrum resource from being overwhelmed.

        There is such a large demand for wireless resources, as a result the electromagnetic spectrum band which is allocated to Wi-Fi is crowding and the problem arrives, which is usually known as “Wi-Fi Spectrum Crunch”.

      To overcome this problem, visible light can be used for communication purpose. Visible lighting is fundamentally much better suited than radio for achieving very high data rate densities. On top of this, visible light can much better be directed and isolated, enabling multiple independent high capacity links, making the technology very suitable for long distance communication.

      In the 21st century, high speed data transmission will play an important role in our daily life. Multimedia information is imagined to be available at any place and at any time. But radio frequency bandwidth has a limited range. Therefore, alternative wireless transmission means have to be explored. Visible light communication using white LEDs offers the potential for such alternative. The main reasons are as follows:

1. Bandwidth is not limited.
2. There is no need for expensive RF units.
3.  As light waves do not penetrate opaque objects, they cannot be eavesdropped and communication is secure.
4. Furthermore, no interference with RF based systems exists, so they can be used in Hospitals, Airplanes etc.

In our project we are using LED's at transmitter side and data is sent through and modulated by modulating (visible) light. At the receiver side, a photo-diode is used which detects the light being incident on it.                                                  Data can either be a text message or an audio signal. A switch is used to separate these two modules.When the switch is off the text module will be on and it will work but when the switch is turned on, the audio module will start working and the text module will be turned off.

      In case of text message an acknowledgement bit is always sent by the receiver to the sender to show that the message transmitted has been received by the receiver.

  In case of audio transmission using visible light, Amplitude Modulation is used. It is a technique in which the amplitude of the carrier wave is varied in proportion to that of the message signal being transmitted. In audio mode, a mic is used on the transmitter end and a speaker is deployed on the receiver end. 

  Real time audio can be sent through this system but there will definitely be some noise generated at the output. To reduce/remove this noise, an RC filter has been used in the circuit.

Project Objectives

Objective of our project is to transmit text and audio message through visible light between two nodes. The maximum distance between the transmitter and the receiver will be up to two or more than two feet depending upon our resources. We are trying to achieve a high-quality transmission with low error rates at 9600 bauds per second.

We will try to maximize both the distance and the data rate depending upon our resources, coding scheme and time available.

Project Implementation Method

In our project, work is to be done on both hardware and software.

In hardware prototype , a transmitter and a receiver circuit is designed. 

Texts will be sent from laptop to microcontroller through USB to serial port converter. At the transmitter end, we will use OOK method and data will be sent through LEDs .    

While at receiver side, a photodiode will be used  which will convert that light into current and then that current is amplified.The amplified current will then be converted back into data.

In case of audio message transmission using visible light, technique of amplitude modulation is used. 

Both the transmitter and receiver must be in LINE OF SIGHT to each other to make the transmission successful.

On software side, programming is done in vb6 and arduino.

Benefits of the Project

Following are some advantages of audio and text signal modulator using visible light communication(VLC) system:

1.  The possibility of using existing infrastructure, instead of investing in and installing new connections, makes the technology environmental friendly and allows for future expansion of the network.
2. VLC can be used in vehicular communication for lane change warning, pre-crash sensing and traffic signal violation warning to avoid accidents. These applications require communication with low latency which is provided by VLC because of its high bandwidth and easier installation due to the existing presence of vehicle lights and traffic signals.
3. VLC also has applications in areas that are sensitive to electromagnetic waves, such as aircrafts and hospitals where the radio signals interfere with the waves of other machines.
4. Visible light is used to provide both lighting and information using VLC techniques. For example, we use lighting in the room to provide the room number identification and other information about the building.
5. Visible light has no associated health concerns like radio waves.
6. RF waves do not travel well in sea water because of its good conductivity. Therefore, VLC communication can be used in underwater communication networks.

Technical Details of Final Deliverable

A system will be developed with an sender and receiver circuit. The sender will use LED to transmit the text and audio message. The receiver will use photo diode to detect the light and then that light is converted into current . Current is amplified and using OOK method in case of text module and amplitude modulation in case of audio module it is converted back into data.

This system is basically modulating the data and audio signals but it is highly secure as visible light is being used to transmit the data which do not penetrate opaque objects and they cannot be eavesdropped. It is very difficult for an intruder to pick up the signal from outside of  the room. So a safe and secure system for communication is developed.

Final Deliverable of the Project HW/SW integrated systemCore Industry ITOther Industries Security , Telecommunication Core Technology OthersOther TechnologiesSustainable Development Goals Affordable and Clean Energy, Decent Work and Economic Growth, Responsible Consumption and ProductionRequired Resources

Item Name	Type	No. of Units	Per Unit Cost (in Rs)	Total (in Rs)
			Total in (Rs)	50340
Microcontroller	Equipment	6	200	1200
Capacitors	Equipment	40	100	4000
DC Battery	Equipment	1	3000	3000
Light Source (LED)	Equipment	1	3000	3000
Stands	Equipment	3	800	2400
LCD Display	Equipment	2	1800	3600
Speakers	Equipment	1	3000	3000
Wire Bundles	Equipment	2	400	800
Arduino KIt	Equipment	2	1200	2400
1k Resistors	Equipment	20	100	2000
Diodes	Equipment	10	30	300
Transistors	Equipment	8	30	240
Potentiometer	Equipment	5	80	400
Silicon Gun	Equipment	1	2000	2000
Soldring Iron and Wire	Equipment	1	3000	3000
Safety Boxes	Equipment	2	1000	2000
Programming Kit	Equipment	1	9000	9000
Stationary, Printing etc	Miscellaneous	1	8000	8000