laser communication ppt
DESCRIPTION
SAFVANMPTC PAINAVUIDUKKITRANSCRIPT
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