Which of the following functions cannot be frequency response of a discrete-time LTI system? a: $H(\omega)=\sin (\omega)$ b: $H(\omega)=\sin (2 \omega)$ c: $H(\omega)=\sin (\omega / 2)$ d: $H(\omega)=\sin ^2(\omega)$

The signal $x[n]=1+\sin (n)+\sin (\pi n)$ is given as input to a low pass filter with cut-off frequency of 2. Select the correct statement from the following: a: Both $x[n]$ and $y[n]$ are periodic b: $x[n]$ is periodic but $y[n]$ is not c: $y[n]$ is periodic but $x[n]$ is not d: Neither $x[n]$ or $y[n]$ are periodic

If the magnitude response of an LTI system is constant and the phase response is linear, then the input and output are related by a: output signal is a scaled and delayed version of the input signal b: output signal is always a scaled version of the input signal c: output signal is always a delayed version of the input signal d: cannot be determined

If the input to an LTI system is $x[n]=e^{j n}$, the system output a: is always of the form $y[n]=A e^{j n}$ b: is always of the form $y[n]=e^{j n}$ c: is always of the form $y[n]=A e^{j n+j \phi}$ d: cannot be determined