Back to Background Information Back to Tutorial/Product Line Information Tutorial An introduction to Fibre Diagnostic Indicators Laying Out the Fibre-Optic System Multimode vs. Single-Mode Fibre-Optic Cables PRODUCT LINE System Design Considerations
	Introduction to Fibre-Laying out the Fibre-Optic System Optical Path Loss-Example #1 240D Video + Return and Data Transmission This example assumes a 3,300 foot (1 kilometer) run of multimode fibre-optic cable with a single splice. It can be seen from this calculation that sufficient budget is designed into the fibre-optic links to accommodate the total transmission power loss. 240D maximum attenuation = 13 dB @ 850 nm/1300nm
	Cable length: (1km) (3.5 dB/km) = 3.5 dB ST Connectors: (2) (1 dB/connector) = 2.0 dB Mechanical splice: (1) (0.5 dB/splice) = 0.5 dB Subtotal: 6.0 dB Optical Headroom (margin): = 3.0 dB Total Loss: 9.0 dB
	Optical Path Loss-Example #2 245D Two-Way Video + Audio + Data Transmission This example assumes a 3,300 foot (1 kilometer) run of multimode fibre-optic cable with a single splice. It can be seen from this calculation that sufficient budget is designed into the fibre-optic links to accommodate the total transmission power loss. 245D1 max attenuation = 13 dB @ 850/1300nm
	Cable length: (.75 km) (3.5 dB/km) = 2.625 dB ST Connectors: (2) (1 dB/connector) = 2.0 dB Patch Panels: (1) (2 dB/splice) = 4.0 dB Subtotal: 8.625 dB Optical Headroom (margin): = 3.0 dB Total Loss: 11.625 dB
	Optical Path Loss-Example #3 170V Standard Video Transmission System What happens if the system's loss calculation exceeds the specified maximum attenuation (or optical budget) established for the selected link? The example assumes inclusion of two patch panels in the path, two butt splices, with the system operating over about two miles of multi-mode fibre-optic cable. 170V maximum attenuation = 13 dB @ 850 nm
	Cable length: (3 km) (3.5 dB/km) = 10.5 dB ST Connectors: Butt splices: (2) (1 dB/connector) (2) (2.0 dB/splice) = = 2.0 dB 4.0 dB Patch Panels: (1) (2 dB/splice) = 4.0 dB Subtotal: 20.5 dB Optical Headroom (margin): = 3.0 dB Total Loss: 23.5 dB
	121VL Long-Haul Point-to-Point Video Transmission With a system budget of 13 dB, clearly there is a problem. The load from the cable length alone consumes most of the budget. How can we hope to transmit the video signal over this distance without an unacceptable amount of signal degradation? By substituting the Series 121VL Long-Haul Point-to-Point Video System with its optical budget of 18 dB at 1300 nm and mechanical splices, our calculation improves substantially.
	Cable length: (3 km) (1.5 dB/km) = 10.5 dB ST Connectors: (2) (1 dB/connector) = 2.0 dB Mechanical splices: (2) (0.5 dB/splice) = 1.0 dB Patch Panels: (1) (2 dB/splice) = 4.0 dB Subtotal: 11.5 dB Optical Headroom (margin): = 3.0 dB Total Loss: 15.5 dB
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