laser communication ppt

W E L C O M E

Presented By: SAFVAN. A

S5 TT Roll. No. 24

M.P.T.C.Painavu

LASER COMMUNICATION

Laser communication systems are wireless connection through the atmosphere

Use Laser beams to transmit information between two locations

No fibers need, a wireless technology Communication over long distances, e.g.

between planets Laser communications terminals transmit

a laser beam and are capable of receiving laser beam

Introduction:

How does it work

Signal Transmitter Laser

ReceiverSignal

Laser Transmitter & ReceiverLaser Transmitt er

Laser Transmitt er

Opti cal Fiber Link

Direct Link

Receiver

Receiver

Laser Diode

Laser diode include Photo diodes for

feedback to insure consistent output

F I l t e r s1. Sun shade over detector2. Shade infront of Lens3. Detector Spectral Response

Security Aspects

Free space Laser Communicati on systems have narrow optical beam path, which are not accessible unless viewing directly into the transmitt er path.

Any potential eavesdropping will result in an interruption of the data transmission

The existence of Laser beams cannot be detected with spectrum analizers

Safety Aspects

The free space laser communicati on system do not require certi fication for handling of operation.

Although the emitt ed laser beam is invisible to the unaided eye, it can cause eye damage if viewed directly at close range for extended periods of ti me.

Transmit Laser Source

Optics

Transmit DataElectronics

Detectors and Signal Processing

Terminal Control Electronics

Power Regulator Structure ThermalTo Equipment

Group

FromhostPower System

To/from Host Data

System

Transmit Beam

Receive Beam

Laser Communication System

Laser Communication System

Input: Digital Data Direct or Indirect Modulation Source Output Passes through the Optical system in to the Channel Optical System: transfer, beam shaping , telescope Optics. Receiver beams comes through optical

system and passed to detectors and signal processing Electronics.

System Characteristics

Link Parameters: Type of laser, wave length, type of link Laser operate in single or multiple longitudinal modes Single longitudinal mode *Laser emits radiations at a single frequency Multiple longitudinal mode *Multiple frequencies are emitted

Link Parameters:Semiconductor Laser Diodes

Reliable Operations as Direct Sources Operating in 800-900nm range High Effi ciency of about 50% Small Size

Solid state Lasers

High power levels, High peak power mode Operating at 1064nm Increasing complexity and reliability

Transmitter Parameters

Laser characteristics, losses incurred in thetransmit optical path, transmit antenna gain, transmitpointing losses

Laser characteristics Peak and average optical power Pulse Rate Pulse Width

Channel Parameters

Consists of Range, associated lossBackground Spectral RadianceSpectral Irradiance

Receiver ParametersThe receiver parameters are the

Receiver Antenna Gain Proporti onal to the square of eff ecti ve receiver diameter in meters and inversely proporti onal to the square of the wave length

Receive Opti cal Path Loss Opti cal transmission loss for systems employing the directi on techniques

Opti cal Filter Bandwidth The spectral width of the narrow band pass fi lter employed in opti cal inter satellite links

Advantages

High data ratesHigh security regarding interceptionLess frequency restrictionsSmaller aperture dimensions and thus reduced size and mass

ApplicationsData relay services for UAVs UAV transmit its data to a GEO stationary satellite

Data relay services for satellites LEO satellite transmit their data to a GEO satelliteInter satellite links Data exchange between GEO/LEO satelliteDeep Space data transmissions Scientifi c data is transmitt ed down to earth, e.g. Mars EarthGEO

Problem, NeedProblem: Limited information is available to operation centers Information not available when needed as transmission time is a bott le neck Real-time decision making not possible or only limited possible

Need: Soluti on for higher data rate transmissions from UAV to Operation centre of long distences

ConclusionsWith the dramatic increase in the data handling requirements for satellite communication services, Laser inter satellite links offer an att ractive alternative to RF with virtually unlimited potential and an unregulated spectrum

The system and component technology necessary for successful inter satellite link exists today