A linear phase channel with phase delay $${\tau _p}$$ and group delay $${\tau _g}$$ must have

In Fig. m(t) = $$ = {{2\sin 2\pi t} \over t}$$, $$s(t) = \cos \,200\pi t\,\,andn(t) = {{\sin 199\pi t} \over t}$$.

The output y(t) will be

A signal x(t) = 100 cos $$(24\pi \times {10^3})$$ t is ideally sampled with a sampling period of 50 $$\mu \sec $$ and then passed through an ideal low pass filter with cutoff frequency of 15 KHz. Which of the following frequencies is/ are present at the filter output?

Which of the following cannot be the Fourier series expansion of a periodic signal?