These are my attempts for these problems. I still need to tackle some of part b). I am not sure about the discrete responses for Yd(ejΩ) of b)i).
I appreciate some guidance or maybe some good sources. Also I am finding b) ii) a bit confusing when it asks "Determine and draw the new specifications for Hd (ejW) such that Yd (ejW) remains as determined in (a)(ii) above." If in a), Hd (ejW) already filtered from pi/2 onwards, why should there be new specifcations to obtain the same Yd (ejW) as in a) ii) ? thanks