In the linear time-invariant system shown in Fig. 1, blocks labeled D represent unit delay elements. Find the expression for $$y\left( n \right),$$ and also the transfer function $${{Y\left( z \right)} \over {X\left( z \right)}}$$ in the $$z$$-domain.

A system having a unit impulse response $$h\left( n \right)$$ = $$u\left( n \right)$$ is excited by a signal $$x\left( n \right)$$ $$ = \,{\alpha ^n}\,\,u\left( n \right).\,$$ Determine the output $$y\left( n \right)$$

A rectangular pulse of duration T is applied to a filter matched to this input. The output of the filter is a

A signal 3 sin $$\left( {\pi \,\,{f_0}t} \right) + \,5\,\,\cos \,\,\,(3\pi \,\,{f_0}t)$$ is applied to an RC low pass filter of 3 dB cutoff frequency $${f_0}$$. Determine and plot the output power spectrum and aslo calculate the total input and output normalized power.