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Introduction to Data Communications
15d. Optical Fibre (cont'd)
Comparison of Optical Fibres
(See image below)
The Wavelength of the light sources is measured in nanometers or 1 billionth of a meter. We don't use frequency to talk about speed any more, we use wavelengths instead.
Indoor cable specifications:
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LED (Light Emitting Diode) Light Source
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3.5 dB/Km Attenuation (loses 3.5 dB of signal per kilometre)
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850 nM - wavelength of light source
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Typically 62.5/125 (core dia/cladding dia)
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Multimode - can run many light sources.
Outdoor Cable specifications:
Advantages of Optical Fibre:
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Noise immunity: RFI and EMI immune (RFI - Radio Frequency Interference, EMI -ElectroMagnetic Interference)
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Security: cannot tap into cable.
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Large Capacity due to BW (bandwidth)
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No corrosion
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Longer distances than copper wire
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Smaller and lighter than copper wire
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Faster transmission rate
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