I am trying to figure out what seems very trivial thing about down sampling and up sampling. The problem that I am facing is how to find the effects of up sample on a signal followed by a filter and/or a filter followed by down sampling. Here is a problem related to this from the Oppenhiem and Schafer book.
I am trying to see what happens to x[n] after it pass the hlp[n], considering that hlp[n] has wc = pi/4. Will there be a gain on this or just the frequency is affected?
Please help, Thanks in advance