Tutorial On Optical Fiber-03

Technologies that use Optical Fibre IDC

Communications Applications ●

Analog » TV modulators » Cable TV example

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Digital » Undersea cables » HDTV

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TV MODULATORS 6 MHz Bandwidth ● Optical amplifiers are expensive ● Normally used as single hop ●

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Cable TV Example Combined fibre/coax network ● Headend modulates signals across 50 550 MHz ● Fibre backbone to get long distance , generally without amplifiers ● Coax network to customers: bidirectional multidrop network, needs amplifiers every 500m. ●

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Cable TV application

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Digital transmission systems

Regenerators at regular intervals give near perfect signals without cumulative noise ● Ideal for long distance, high bandwidth systems ● Low loss of fibres enables regenerators to be widely spaced ● Dielectric cables protect against lightning and high voltage areas ●

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Undersea fibre cables Modern undersea cables use digital technology ● Delay in satellite links limits their applications for telephony ● Very high bandwidth systems now being installed ● China-Korea cable 550 km path needs only 3 intermediate repeaters for 565Mb/s system . ●

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HDTV Analog bandwidth of 27MHz ● Requires 600Mb/s to 1 Gb/s when digitised ● Using compression needs about 150Mb/s ● Becomes feasible with fibre optic transmission. ●

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LOCAL AREA NETWORK APPLICATIONS FOIRL ● 10 BASEF ● 100 BASE-FX ● 100 VG-ANYLAN ● FDDI ●

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FDDI

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10 BASE F

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MAN & WAN APPLICATIONS SONET AND SDH ● B-ISDN ● ATM ● FRAME RELAY ● FIBRE CHANNEL ●

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Sensor applications Optoelectronic sensors can be placed in more appropriate locations using fibres ● Light travelling in fibre cables can be changed by environment. These small changes can be used as environmental sensors. ● Measure pressure, temperature, strains, magnetic fields, acceleration etc. ●

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PROXIMITY SENSOR

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LIQUID LEVEL SENSOR

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FIBRE OPTIC GYROSCOPE

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Bundles of fibres ●

Random bundles used for illumination » Signs » Light into awkward places

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Coherent bundles used for imaging » Medical endoscopes

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