Why Does the Eye Diagram Exclude f2?

[fran1942]

Homework Statement

draw the eye diagram you would expect to see should a digital signal be passed through a transmission line with a bandwidth limited to three times the maximum bit rate of the digital signal.

the answer is "Only f1 and f3 pass through"

My question is, what about f2 ?
Why does the answer to this question read f1 & f3 rather than f1 - f3 (including f2) ?

Thanks for any clarification.

 

[berkeman]

Homework Statement

draw the eye diagram you would expect to see should a digital signal be passed through a transmission line with a bandwidth limited to three times the maximum bit rate of the digital signal.

the answer is "Only f1 and f3 pass through"

My question is, what about f2 ?
Why does the answer to this question read f1 & f3 rather than f1 - f3 (including f2) ?

Thanks for any clarification.

What is the frequency domain spectrum for a square wave in the time domain?

 

[fran1942]

Hello, thanks for your help. I have tried thinking about this one, but I still can't understand why f2 is not mentioned in the answer to this question.

If you could please offer some further explanation that would be great.
Thank you.

 

[berkeman]

Hello, thanks for your help. I have tried thinking about this one, but I still can't understand why f2 is not mentioned in the answer to this question.

If you could please offer some further explanation that would be great.
Thank you.

You didn't address my question/hint. Try Googling my question if nothing still comes to mind...