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 System Design Considerations It is the system designer's job to determine the most efficient and cost-effective way to convey optical power. In order to do this, the designer must understand the limitations of and the tradeoffs between various elements of the systems. Will the system be required to transmit video? audio? data? or a combination of these signals? One way or bidirectionally? Over what distance? What is the optical loss budget of the system that is being considered? What is the sum total of the optical power loss of the system and how does this figure compare to the optical budget specified for the system?
	Transmission Loss Optical loss, or total attenuation, is the sum of the losses of each individual component between transmitter and receiver. The primary causes of optical attenuation are: Fibre loss/km Coupling loss Connector loss Splice loss When it comes to measuring these losses, it's not possible to be exact. Manufacturers' typically state ranges and allowances must be made for such things as type of splices, the age and condition of the source emitter, and the environment including temperature variations. Figure 3 provides a very brief chart as a reference when estimating power loss.
	Maximum Attenuation Specification All of Fibre Options' systems include a maximum attenuation specification. The higher this number (expressed in decibels), the further the system will function. This figure, also referred to as the optical budget, identifies the capability of each Fibre Options transmission link. It is the maximum amount of signal loss a system will tolerate and still function satisfactorily. The overall path loss, or "link budget" as it is sometimes called, can be determined by: Using an optical meter to measure loss. Calculating the loss of system components. This latter method considers the following factors, each with their associated loss: connectors, splices, patch panels/jumpers, and optical headroom. Adding all of these factors to make sure their sum total is within the maximum attenuation figure will ensure that the system will operate satisfactorily.
	Typical Optical Loss Values Figure 3 ITEM LOSS CONNECTOR TYPE ST FC/PC   1.0 dB 0.75 dB FIBRE TYPE Multimode @ 850 nm Multimode @ 1300 nm Single-mode @ 1310 nm Single-mode @ 1550 nm   3.5 dB/km 1.5 dB/km 0.6 dB/km 0.4 dB/km SPLICE TYPE Butt Mechanical Fusion   2.0 dB 0.5 dB 0.2 dB Patch Panel 2.0 dB Laying Out a System Several examples of system layouts have been provided on this tutorial-Laying Out the Fibre-Optic System- based on hypothetical, yet typical, situations. By reviewing these examples, it's possible for the user to better understand how to plan a fibre-optic system that will function effectively for a given application. Selecting system components based on a relatively simple calculation of typical optical loss values vs. the maximum attenuation (optical budget) that is specified for the equipment under consideration, will provide the hoped-for results.
	To visit Fiber Options home on the Web, click here. BACK TO TOP Introduction to: Diagnostic Indicators | Multimode vs. Single-Mode | System Design Considerations | Laying Out the Fibre-Optic System | Fibre-Optic Cables Back to Background Information | Back to Tutorial/Product Line Information | Browse Product Index | Glossary of Terms Contact Us | Company Profile | Access Control Systems | Twisted Pair | Coax Splitters | Enquiry Form
	This site was designed and produced by Internet PageMakers