Hi Joseph,
You are using the time delay correctly!
1) Noise bins are a convenient signal representation for noise. Each “bin” is given a bandwidth and amplitude, thus a wide range of frequencies can be modeled and makes calculating SNR much easier. A sampled signal will need a much higher sample rate to model a wider range of frequencies and it is not quite as easy to determine the power of the noise.
What the convert noise bins option does is when a sampled signal overlaps the noise bin signal the noise in the noise bins is converted to a sampled signal and added. Normally I would suggest using the convert noise bins (in OptiSystem 13.0 this option is now set by default), because you are not working with a WDM type network, which would benefit from the large frequency representation. That being said since you are interested in the electrical SNR value, you will HAVE to use noise bins. Our WDM Analyzer can calculate the SNR of a sampled optical signal but the electrical carrier analyzer is not able to yet.
Another reason why you would choose to convert noise bins is because some types of models don’t modify noise bins, because they might be a time domain effect, like nonlinearity, so converting the noise bins will increase the accuracy of the simulation, although since noise power is usually quite low it has a minimal impact. Let me know if this was a sufficient explanation!
3) You can use this component fine and it will compare noise bins to the signal power to calculate the SNR. There are two frequencies simply to allow you to compare values. You need a filter to be able to define the power of a frequency signal. Other wise the “power” is given by W/Hz.
Hope this clarifies the issues!