Beckhoff CU1521 Series - Page 34

Commissioning/application notes
CU1521-xxxx, CU156134 Version: 2.5
Attenuation budget
Parameter Number Value
Fiber loss attenuation (0.8dB/km) 2.1km 1.68dB
Connector insertion attenuation
(0.25dB)
2 0.5dB
Splice insertion attenuation (0.3dB) 3 0.9dB
Attenuation budget 3.08dB
If the attenuation budget is now subtracted from the power budget, a power buffer of 4.42dB results. This is
greater than 3dB and is therefore sufficient as a buffer for most applications, so that an additional splice or
slight soiling of the fiber would not lead to failure of the data transmission.
If several values are given for a parameter in the data sheet for transceivers, cables or connectors, the worst
value should always be taken and used for the calculation.
For the transmission link under consideration, the bandwidth/length ratio specified in the data sheet for the
fiber should always be considered in addition to the attenuation and, as shown above, one should calculate
whether the implementation of the length of the transmission link is possible with the desired bandwidth and
the fiber.