I am new to signals and systems. I have an elementary questions:

I need to add noise to a Pulse Generator in Simulink.
Suppose that you have a digital signal, that raises to 1 every 5 sec, holds it for 5 sec, and falls to 0 and holds it for another 5 sec. I want the generator to raise and fall the signal, not exactly at 5th sec, but with a small random error. Say, in 5 sec +/- 5 mili sec. Do you know how can I write the math for that, or to modify Pulse Generator in Simulink?

Thank you,