Multimedia Audio Transfer System Using Laser

Multimedia Audio Transfer System Using Laser:

Introduction

Our project is divided into two distinct sections: Audio transmission and reception via hardware. The transmission media is unguided. The main objective of this project is primarily to realize a transmission-reception system to transfer sound via Laser without a guiding medium, using Intensity Modulation with very little quality loss ( up to 99.99% ).

Laser technology is similar to Fibre Technology, just the change in Medium from Fibre cable to Free space.

Literature survey

S.N	Title	Author	Understanding
1)	Multimedia audio Transfer Technology	M Natarajan	Multimedia system combines the digital form of images,graphics ,audio,electronic signals or video with traditional text data.Multimedia can be as simple as a few images with some accompanying text to a multimedia presentation using video clips, sound, images, animation and text.Multimedia files use a lot of data when in a digital format. Video is the most demanding
2)	Transmission of Sound Using Laser	Navneesh Singh Malhotra	The acronym laser stands for “light amplification by stimulated emission of radiation.” Lasers work as a result of resonant effects. The output of a laser is a coherent electromagnetic field. In a coherent beam of electromagnetic energy, all the waves have the same frequency and phase.

Why Laser Technology.

Currently Fibre optics & Microwave are the most used technology

Why not Fibre optics?

Installation cost
Maintenance cost
Cannot be used in Satellite links

Why not Microwave?

Laser beam width is narrower than that of Microwave antennas.
Bandwidth is very much larger for laser than microwave.
Laser is far more secure than microwave.
Low power is needed to operate Laser than Microwave.

Working

From the Input, the signal is passed through a capacitor that passes only audio and blocks any direct current (DC) that may influence the biasing conditions of the amplifier.
A potentiometer is used as a volume control for the audio signal which simply acts as an attenuator.
The signal reaches LM386 low voltage audio power amplifier IC, which amplifies the audio input by means of power from the battery

A capacitor and resistor are used at the output of LM386 IC which forms a filter circuit, which prevents high-frequency signals coming from the amplifier, most probably noise picked up or generated in the amplifying process of LM386 IC.
The signal is then transferred to Laser Module and using using Intensity Modulation the signal is directed to receiver Section

The voltage variation in the solar panel at the receiver section is amplified by a low voltage audio power amplifier LM386.
This signal is then passed through a capacitor and resistor at the output of LM386 IC which forms a filter circuit, which prevents high-frequency signals coming from the amplifier, most probably noise picked up or generated in the amplifying process of LM386 IC and transmitting process from Laser such as wind noise, dust noise, etc..

Block Diagram

Circuit Diagram (Transmitter)

Circuit Diagram (Receiver)

Components

S.N	Components Name	Description	Quantity
1	IC	IC LM 386	2
2	Receiver/Transmitter	Solar Panel / Laser	1
3	I/p / O/p	Audio Jack / Speaker	1
4	Power / Switch	Battery (9V) / (on/off switch)	2
5	Resistors	10,10k,220,100,56 (ohms)	8
6	Capacitors	0.047,10,100,220 (micro F)	9

Applications

Defense and Sensitive areas
At airports for communication across the runways
Mass Communication
Nasa: Satellite to Satellite communication & Earth to satellite Communication.

Advantages.

The advantage of laser communication is that it allows a very fast communication service between two or more devices than other modes of communication.
It can provide a speed of more than 1GBps.So it overtakes the LAN or wireless LAN comprehensively.
Laser communications systems have the benefit of eliminating the need for broadcast rights and buried cables.
Laser communications systems can be easily deployed since they are inexpensive, small, low power and do not require any radio interference studies. The carrier used for the transmission signal is typically generated by a laser diode. Two parallel beams are needed, one for transmission and one for the reception.
The transmitting and receiving stations are smaller and lighter for a given range. Less overall power is required for the given distance and data rate. A higher data rate may be achieved for a given distance and power output.

Disadvantages.

The essential disadvantage of free-space laser communications systems is that they require direct line-of-sight.
Operational distance is also a variable if there are Intervening materials such as rain, smoke, fog, glass, etc. which reduce the light intensity by a combination of absorption and refraction.
Guided laser communication systems have many of the same problems as guided radio systems.

Future Scope

It is more secure and provides high bandwidth requirements. The low power consumption is also a great advantage.
It can be the most used technique worldwide in the near future.
Laser technology can also be used to avoid train & plane collisions and also for communication between Driverless Cars.

References

Points Covered