FREE SPACE OPTICAL COMMUNICATION
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WIRELESS CONNECTION
1. DISTRIBUTE DATA EVERYONE ,SECURITY IS JUDGED BY THE WEP
2. LICENCE REQ. TO PLANNING & COORDINATION
3. SUSCEPTIBLE TO RAIN ,LINK LENGTH
4. PP MICROWAVE PROVIDE HIGHER CAPACITY
Eg. LMDS
FIBER OPTIC BASED SOLUTION
1.FIBER OPTICS ARE TWO TYPE
A) SINGLE MODE [UPTO 60KM]


B)MULTI MODE [UPTO 2KM]
2)FIBER OPTICS ARE
SECURE
PROVIDE SPEED IN TERABYTE
PROTECTED FROM TAPPING
IMPOSIBLE TO DETECT LIGHT PULSE
FREE SPACE OPTICS
1)NO CABLES REQUIRED
2)TRANSMITTED IN ATMOSPHERE
3)REQUIRE LINE OF SITE AVAILABILITY


ADVANTAGES
FSO LASER BEAM CANNOT BE DETECTED WITH RF METER OR SPECTRUM ANALYSER
LOS PATH CANNOT BE INTERCEPTED EASILY
DATA CAN BE TRANSMITTED OVER AN ENCRYPTED CONNECTION
FREEDOM FROM LICENSING AND REGULATION
POSSBLE TO MOUNT INSIDE THE BUILDING


.ATMOSPHERE CHALLENGE
1.FOG
IT AFFECT ON NEAR INFRARED WAVELENGTH
AND HAVE SAME EFFECT AS RAINFALL HAVE ON THE RF
.PHYSICAL OBSTRUCTIONS
1.THESE CAN BE REMOVED BY WIDELY SPACED
REDUNDANT TRANSMITTERS AND LARGE RECEIVE OPTICS


.SCINTILLATION
THESE CAN BE REMOVED BY AUTOMATIC GAIN CONTROL CHAR.,TUNED RECEIVED
FILTERING,CLOCK RECOVERY PHASE LOCK
LOOP TIME CONSTANT
.SOLAR INTERFERENCE
IT CAN BE COMBATED BY
1.LONG PASS OPTICAL FILTER WINDO
2. OPTICAL NARROWBAND FILTERING