Simulink filter using frequency response transfer function

Hi,

My main problem is this: I'm building a fiber optical communication system using simulink.

As a source, I use a bernoulli generator, then this signal runs to a low pass filter and the exit is the signal equivalent to a signal that comes off a led, so the emission part is done.

The problems begins at the transmission channel. I want to do a filter that simulates the dispersion effect in the fiber (only chromatic dispersion), but I don't know how. I only have a transfer functions like exp(-j*alpha*f.^2) and I don't know what to do with this. What's the right procedure to implement this kind of t.f. in a analog filter at the simulink?

Any help is welcome.

Kind regards

[Rick Rosson]

Do you have the Signal Processing Toolbox and/or the DSP System Toolbox?

Answer 1

[Rick Rosson]

Here's a start:

   beta = alpha/(2*pi)^2;
   omega = 2*pi*f;
   phi = -beta*omega.^2;
   groupDelay = -2*beta*omega;

   figure;
   plot(f,groupDelay);

   Fs = 2*max(f);
   N = length(f);

   spec = fdesign.arbgrpdelay(N,f,groupDelay,Fs);
   chan = design(spec,'iirlpnorm','MaxPoleRadius',0.95);
   fvtool(chan,'Analysis','grpdelay');

Answer 2

[Francis]

First let me thank you for answering, but I remain with some doubts.

Here the alpha that you speak is the attenuation? Because the alpha that I refer is a constant equals to pi^2*beta2*L, where L is the link distance, and beta2 is the group velocity delay.. And yes, I have all the toolbox of the simulink.

[Yuang]

Hi,

May I ask how did you simulate the chromatic dispersion in simulink eventually? Thanks!

Best.