G.654 normally deploy as a submarine fiber, while since it is submarine, can not avoid long distance transmission, so RAMAN should be considered in this situation.
Remote Pump System
The point to point system is based on G.654 fibers and is designed to carry 80 wavelengths. Currently, five 40G channels(192.1, 192.2,192.3,192.4,192.5) have been deployed in the system, and dummy light is emitted for the other idle wavelengths.
A forward Raman, backward Raman, and pump are configured to counter extensive insertion loss over the span.
Remote Pump System Power Commissioning
Before power commissioning, hardware installation should be done without any issue, especial for fiber splicing and connection. Power commissioning should be done following below steps:
Step 1. Commissioning the power at transmit Amp, ensure the power flatness and Transmit Amp total output meet the requirement
- According to the specification table above for 40G DQPSK signals in a G.654 fiber system, the OA board does not output the maximum power of 23 dBm when there are 80 wavelengths, and the output power shall be adjusted to 21 dBm.
- As 40G DQPSK signals have a high rate, extensive non-linear effects will result from impact of forward RPC, in an 80-channel system with a 50 GHz channel spacing. To counter the non-linear effects, the incident optical power must be reduced.
Step 2. Setting locked power for the Raman pump following below value
- Setting locked power for the two pumps of the forward RPC:
Pump 1: 26.4 dBm
Pump 2: 26.4 dBm
- Setting locked power for the two pumps of the ROP
Pump 1: 26.3 dBm
Pump 2: 26.3 dBm
- Setting locked power for the two pumps of the backward RPC
Pump 1: 25 dBm
Pump 2: 22 dBm
Step 3. After the pump locked power is set for the Raman board, flatten OSNR among channels at the receive end by adjusting the single-channel attenuation on the WSM9 board at the transmit end. The OSNR variation must be within 2 dB (integral testing on OSNR)
IPA Configuration at the Raman System
IPA configuration can be done following the product manual, for Raman system, IPA detection mode is important, there are three ways to configure IPA detection mode:
- Receive Amp detect
1) Measure the input power (A) of the OA board behind the Raman board when services are running properly.
2) Shut down the lasers on the upstream OA board and forward Raman board (CRPC03), turn on the laser on the backward Raman board (CRPC01), and measure the input power (B) of the OA board behind the Raman board (CRPC01).
-If the value of (A – B) is larger than 3 dB and the value of (A + B)/2 is within the [-35, -14] range, then configure IPA detection boards and set the IPA detection board threshold as the value of (A+B)/2.
– If the condition described in sentence (1) is not met, do not configure detection boards. In this situation, this condition is not used to determine whether a fiber break has occurred.
- Backward Raman detect
Applies only when one of the 192.4 THz, 192.3 THz, 192.2 THz, and 192.1 THz wavelengths is configured in the system
1) Obtain the input power (RamanA) reported by the backward Raman board (CRPC01) when services are running properly.
2) Shut down the lasers on the upstream OA board and forward Raman board (CRPC03), turn on the laser on the backward Raman board (CRPC01), and read the input power (RamanB) reported by the backward Raman board (CRPC01).
– If (RamanA – RamanB) is larger than 4 dB, enable the alarm function for the Raman board and set the power threshold for the Raman board to (RamanA + RamanB)/2.
– If (RamanA – RamanB) <= 4dB, set Raman Board Alarm Reporting to Disabled so that this condition is not used to determine whether a fiber break has occurred.
- Auxiliary card(SC1/OTU) detect
When configuring the OTU/OSC board as an auxiliary detection board, ensure that the OTU/OSC board is installed in the same optical NE with the shutdown board.
FAQ
[Question]: For 80 wavelengths system, the wavelength performance is better when the output power of transmit amp set to 19dBm other than 21dBm, so should the output power of transmit amp be set to 19dBm?
[Answer]: Despite a little better BER for +19dBm than +21dBm, but more OSNR margin for +21dBm than +19dBm, OSNR margin is high enough (above 8dB both for +19dBm and +21dBm) to ensure the system running steady in the long-term time
- One IPA configuration example
– Detection Card: Null
– Shutdown Card: Transmit Amp at the same site with detection card
– RAMAN amplifier: the downstream(backward) CRPC01
– Enable/Disable: Enable(Enable/Disable indicates whether to enable the IPA function immediately after the IPA configuration. Set the parameter to Disabled during IPA creation, and then set the parameter to Enabled after commissioning)
– Restart Mode: Manual(for restarting IPA,you should make an IPA test first, then turn on both forward/backward Raman Laser manually, then IPA will restart)
– Safe control switch: On
– Raman alarm: Yes
– Detection card alarm threshold: set is as default -30dBm
– Enable Auto laser shutdown at raman: yes
– Raman Theshold: depend on test data
– Aux raman: Upstream(Forward) RPC03
– ROP card: set the ROP card
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