FREE SPACE LASER COMMUNICATION

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FREE SPACE LASER COMMUNICATION

TALK FLOWBasic overviewSystem overview IntroductionMulti- path laser communicationAdvantagesDisadvantagesSecurity aspectsSafety aspectsApplicationConclusion 2/18

INTRODUCTION

What is LASER?It is a source of coherent EM waves at infrared

& light frequencies.Operating range is from 430 to 750 THz.Information carrying capacity is immense.

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What is Free-space LASER Communication

Data is transmitted by modulated laser light where the laser beam travels through the atmosphere.

It’s a wireless connection through the atmosphere.

The laser light across the link is at a wavelength of between 780-920 nm.

Two parallel beams are used, one for transmission and one for reception.

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Basic overview of free space laser communication

Runs in infrared spectrum.Optical signal is in the range of THz

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System overview of free space laser communication

The system consists of two transceivers, each capable of simultaneously transmitting & receiving either analogue or digital information.

User selects between either analogue or digital information via means of two switches.

In normal operation, the system is a full duplex analogue/digital communicator.

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Hardware:It is divided into two main categories: The analogue transceiver-including VU

meter. The digital transceiver.The design incorporates three circuits

which perform analogue modulation, digital modulation, and signal strength display.

The completed system houses all these modules as a single unit, sharing the critical input & output components.

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Free space multi-path laser communication systems:

All laser beams hit the target point(optics & photo-diode of the receiver)coherently.

This is achieved by phase control analog circuit.

Advantages of multi-path laser communication systems:

Robustness in performance(not all beams are interrupted simultaneously).

Better safety.Easier design and built of stable laser sources

and optics. 10

The degradation effects can be categorized as:

Propagation effect:Due to presence of heavy fog, snow or smoke

blocks the line-of-sight between the units.Sun is interfering the laser beam.Mechanical insufficiencies:As the optical beam is narrow, the link

performance is sensitive to vibration, wind sway, and thermal expansion of the equipment.

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Advantages: Eliminates the need of buried cable installations. No need of Govt. licensing. No spectrum fees have to be paid. No radio interference. Systems are quickly deployable. High data rate & security. More highly directional then RF communication. Extremely high bandwidth. Large information throughput that is many times greater

than RF communication. Small antenna size. One third in mass. Half in power requirement. 12

Security aspects:

Due to narrow optical beam paths, they are not accessible unless viewing directly into the transmitter path.

Existence of laser beams cannot be detected with spectrum analyzers.

Safety aspects:Do not require certification for handling or

operation.Although the emitted laser beam is invisible to

the unaided eye, it can cause eye damage if viewed directly at close range for extended periods of time.

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Applications:Transmission of digital computer data

(LAN interconnect) video, voice, multiplexed data etc.

Provides bitrates up to 1.25 Gbps at shorter distances.

Suitable for temporary connectivity needs such as at conventions, sporting events, corporate & university campuses, military operations etc.

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Conclusion:Laser-com technology on path to be operationally

fielded in space in next decade Revolutionary increases in capability and reductions

in size ,weight & power.Telecom-like interoperability standards should help

keep costs down.

Continued R & D to achieve ultimate potential Laser-com to/from aircraft Multiple users per terminal(multi-access)Advanced technology for high sensitivity and high data

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“Thank u”…..all…..

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