Here I use the CT signal x=sin(2*pi*t) with a period of 1 sec:
Producing a periodic discrete time signal from the signal above with sampling rate SR=0.01:
Changing the sampling rate to produce a non-periodic DT signal SR=0.09:
Making a Periodic Signal from a sum of non-periodic signals
Using the non-periodic $ \ y= \sin(10 \pi \ln(t)) $ I used in homework 1, and summing $ \ \sum_{k=3} y(t+k10) $ on a finite interval to create a periodic signal:
