Amplifier settings¶
Operating mode: ACC recommended¶
Use manual pump current control (ACC) for precision time or frequency transfer. The AGC feedback loop adds noise that can slightly affect the phase and amplitude of a highly precise signal. If power levels along the path do not fluctuate often, set the pump current manually and correct large changes from your management system.
Setting the pump current¶
Start the CLI with sysrepo-cli.
Recommended initial values:
Module |
Initial pump current |
|---|---|
C-band |
62 mA |
L-band (1572 nm) |
72 mA |
set czechlight-bidi-amp:c-band/pump-manual-current 62
set czechlight-bidi-amp:narrow-1572/pump-manual-current 72
commit
copy running startup
commit applies the change immediately but does not store it.
copy running startup saves it to flash so it is loaded at boot.
Then fine-tune the current while watching the power levels on the ports (Reading the values). The target is a gain of about 23 dB (C-band) and 22 dB (L-band), which means the difference between the input at one side (for example WEST) and the output at the other (EAST) is close to those values.
Reading the values¶
get czechlight-bidi-amp:*
The output lists these nodes for each module (c-band and narrow-1572):
Node |
Meaning |
|---|---|
|
Current you set (mA) |
|
Actual pump current (mA); should be close to the set value when the pump is on |
|
Power in the east-to-west direction (dBm) |
|
Power in the west-to-east direction (dBm) |
What to expect on a correctly set link:
Input power within the specified range (C-band: −30 to −10 dBm; L-band: −30 to −12 dBm).
Output minus input about 23 dB (C-band) or 22 dB (L-band).
Measured pump current close to the manual setting.
If the measured current is 0 or the powers are far outside these ranges (for example inputs near −50 dBm), check that the pump is enabled and that the fibers are connected and clean.
Switching the pump off¶
set czechlight-bidi-amp:c-band/pump/disabled
commit