Calculating the loss in a multimode link

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This chapter describes how to calculate the maximum allowable loss for a FICON®/FCP link that uses multimode components. It shows an example of a multimode FICON/FCP link and includes a completed work sheet that uses values based on the link example. Be sure to use the fiber loss corresponding to the proper wavelength for multimode links; refer to the FICON/FCP, and coupling link physical layer documents for more information. The use of an optical mode conditioner is considered to be an extension of the source and receiver, and does not enter into the link loss analysis.

Each link has a loss (attenuation) whose value depends on the loss induced by each cable, connector, and splice. This value, when calculated, cannot be greater than the maximum link loss.

Use the following explanation and refer to the configuration example (Figure 1) and the work sheet example (Table 1). Although actual values should be used if possible, this example uses the typical loss values shown in Table 1.

Planning your individual optical fiber links involves:

  • Determining the acceptable link loss of the supported products
  • Calculating the link loss
  • Determining whether new or existing fiber cable will be used
  • Selecting jumper cables.