Documentation request: How to find parameters for 'advanced' EDFA model

[DirkSchroetter]

Maybe too much to ask here, but would like to understand how to calculate the nf_fit_coef given a table of [gain, NF] values and ask for a quick documentation on this subject.

Is it just trying to some up with the coefficients a,b,c,d for the following funtion:

ax**3 + bx**2 + cx +d = NF(x) for x indicating the gain ?

[ojnas]

There is some more documentation here:

https://github.com/Telecominfraproject/oopt-gnpy/blob/master/examples/edfa_model/amplifier_models_description.rst

The sentence "It uses a 3rd order polynomial where NF = f(gain)" in the main README is maybe a bit misleading and should probably be changed.

[ojnas]

So to clarify, in your equation above x does not represent the gain_target directly but rather gain_target-gain_flatmax. (The documentation I linked to is maybe even more confusing because of the seemingly erroneous minus sign in NF = f(-dg).)

[DirkSchroetter]

Hello Jonas,

Thanks for the update. My tests of over the weekend made me conclude the same thing. So the NF estimation the advanced_model are actually called with “-dg”. And dg = gain_flatmax – gain. So with the coefficients chosen in such a way that f(-(gain_flatmax – gain)) == NF(gain) I get the correct noise figures.

Thanks for all your help

/Dirk