When it says "Periodic Digital Signal is composed of periodic composite analogue signal with infinite bandwidth with discrete frequencies" and "Non-periodic Digital Signal is composed of non-periodic composite analogue signal with infinite bandwidth with continuous frequencies" in the book, I get very confused.
I understand that digital signals are composed of many composite analogue signals that form the whole digital wave. But I still find this statement rises a lot of questions.
- Does "Discrete Frequencies" mean the frequency values are in integer numbers only and not any real numbers?
- Does "Continuous frequencies" mean the frequency values can be in integer or real numbers?
- If the above 2 questions are false, then why periodic digital signal has discrete frequencies and non-periodic digital signal has continuous frequencies? Periodic signals can be "continuous" too, isn't it?
I could have just memorise this statement but it wouldn't really make sense unless I know exactly what this whole thing mean.
Thanks for any help!