In some projects we need to generate dummy channels, for example when we need to implement IPA function for some links with Raman amplifiers. This arcticle describre the steps to implement a dummy
The "picture 1" shows a connection diagram that use Dummy Channel in order to set properly the IPA function when we use Ramam amplifiers.
In this case, we need to follow these steps:
1.-Log in by Navigator to the NE.
2.-Query the current work mode of OAU board:
:cfg-get-oaworkmode: bid, port, path;
3.-Set power lock mode in order to generate optical power by ASE (it is not necessary to connect any signal in the IN port) :
:cfg-set-oaworkmode: bid, port, path, powerlock, workpara;
For example: set the output power at 5dBm:
:cfg-set-oaworkmode: bid, port, path, powerlock, 50;
4.-If we want to set back to gain lock mode, we can use this command:
:cfg-set-oaworkmode: bid, port, path, gainlock, 0x7fffffff;
5.-To set the power in the amplifiers we need to consider the input power of the second amplifier (it means the working range of the amplifier).
6.-Finally we have to calibrate each lambda modifying each VOA in M40V.According to the normal procedure to calibrate lambdas.
To implement dummy channels we have to be careful in power of amplifiers, specially in the second one. If the power is too high, amplifier may give different lambdas with different gain, make all lambdas
not flat. When we use MCA board to scan, if the power difference is too large(more than 8 db), the MCA will think the lambdas which is lower are noise, so will not show them. But if you use Optical Spectrum Analyzer, all lambdas will showed in screen.
-To implement dummy channels, we have to be careful of optical power in each board of the dummy channel configuation. specially to check the working range of the amplifiers. Notice that we need to use
commands in Navigator to set power lock mode in the first amplifier.
-Check the hardware conection is correctly done.
-Calibrate all lambdas in the DWDM system as usual.
-Dummy channels is useful to simulate full DWDM system and to set IPA function, because "threshold Raman amplifier" paramenter varies according to total power in the DWDM link.