I am trying to crate bidirectional system but there seems to be a problem which I don't know. Please see the attachment. The problem is that I can't see the sampled spectrum from Spectrum Analyzer-1.
Change the signal index parameter from 0 to 1 in the spectrum analyzer-1 window as you are simulating a bidirectional system. Then you will be able to see the sampled spectrum.
Double click on the spectrum analyzer-1 window. Then click the up arrow of the signal index parameter shown on right upper side of the spectrum analyzer window. It will display the sampled spectrum.
in your project , layout parameters window - signals - iterations is set as 3 . so you can vary the signal index up to 2 , the visualizer with signal index 2 will be the exact result for your iteration. this signal index is mainly used in project with feedback concept... such as laser, amplifier with residual pump utilization.