CANOGA PERKINS 2370 High-Speed Universal Fiber Optic Modem - Manual (Page 47)

EdgeAccess Universal Chassis System
Model 2370 Model User Manual 5-3
f. If the reading is incorrect, repeat the measurement with a different test cable. If the power
level is still not within range, call Technical Support.
If you know the link attenuation, subtract that value from the 2370 Tx output value to determine the
power expected at the remote cable end, which is the input power at the remote receiver, and skip this
section. Otherwise, continue these steps to use the 2370 to measure the link attenuation.
g. At the local site, connect the fiber link cable to Tx on the 2370.
h. At the remote site, set the optical power meter to the proper wavelength and connect it to the
fiber link cable.
i. Record the optical power level and compare it with the sensitivity level listed on the data
sheet for the link fiber type.
j. Subtract the remote power level from the value for the transmitter output power at the local
site. The result provides the link loss, in dB. This power level must not exceed the limit for
Rx sensitivity listed on the data sheet for the remote unit.
Note: If you cannot determine the Rx sensitivity, contact Canoga Perkins Technical Support
Department for assistance.
k. Repeat this process at the other site.
2. If the cable loss exceeds the loss budget for the modem, either a cable or a connector is faulty. If
the cable loss is within specification, follow these steps to run the loopback test; for details, see
Section 4.12:
a. At the Diagnostics screen, set the near-end modem to Remote Loopback.
b. Set the BERT tester for the clocking, data rate, and format used for the circuit; use the
existing interface cables if possible.
c. Connect the BERT tester in place of the near-end device and run the BERT test.
3. If the remote loopback and BERT tests pass, optically loop back each modem and repeat the
BERT test. If the test fails, the modem is faulty.
4. If the optical loop back and BERT tests pass, set Local loopback on each modem and repeat the
BERT test. If the test fails, the modem is faulty.
5.3 Fiber Optic Diagnostics
If the Loopback Test passes, but the modems still fail, make these checks:
• Check that the fiber optic cables are connected in the standard Tx to Rx and Rx to Tx scheme and
labeled near each end with the signal direction, source, and destination.
• Check that the data rate is set correctly.
• Check that the operating mode (internal/external/slave) is set for synchronous transmission or that
the circuit is set for asynchronous transmission.
If the problem persists, contact Canoga Perkins Technical Support.