Lucent Technologies Release 6 manual Optical Cross-Connect Hardware

DEFINITY Enterprise Communications Server Release 6	Issue 5
Installation and Test for Multi-Carrier Cabinets 555-230-112	May 1998
A Connecting Fiber Optic Cables
Optical Cross-Connect Hardware	Page A-6

Optical Cross-Connect Hardware

Optical cross-connects consist of a preterminated lightguide shelf or Lightguide Interconnect Unit (LIU) with lightguide troughs. A multi-mode or single-mode fiber optic cable connects the lightwave transceivers on the DEFINITY System to connector panels inside the shelf or LIU. Circuits can be changed by moving the patch cord from 1 point on the connector panel to another.

Measuring Single-Mode Power in the Field

The data pattern on the link influences the optical power measurement. The duty cycle that the transceiver is sending when the DEFINITY System is idle is a 30% on (“1”) and 70% off (“0”) data pattern. This implies that the optical reading will be about 2.3dB less than the typical output power specification (-8dBm). Calculate all power budget analysis at 50% duty cycle for both transmitter output power and receiver sensitivity.

The following information is provided for field troubleshooting use only and is not intended for fiber budget analysis.

The power measurement is taken from the TX connector, through the entire fiber link, and to the RX connector on the opposite end of the link (remote EPN). Refer to Figure A-2 for a typical fiber route.

1.Remove the fiber cable from the RX connector at the local 300A.

2.Attach the power meter to the fiber cable. Note the reading.

3.Reconnect the RX cable.

4.Repeat the test at the RX connector at the remote 300A. Note the reading.

5.Reconnect the RX cable.

6.Using Figure A-1, determine the type of in-line attenuator required for each direction in the tested fiber link.

NOTE:

Using the maximum power budget of 17dB in any fiber link may cause problems if the fiber plant is damaged and additional connectors or splices are added. Maintain a margin of at least 1dB; 2dB is the industry standard.