Some properties are given below: (i) A signal f (t) and its Hilbert fh(t) have the same energy density spectrum. (ii) A signal f (t) and its Hilbert transform fh(t) have the same auto correlation function. (iii) A signal f (t) and its Hilbert transform fh(t) are mutually orthogonal i.e infin; f(t) fh(t) dt = 0 (iv) If fh(t) is a Hilbert transform of f (t), then the Hilbert transform of fh(t) is f (t)i.e. If H [f(t)] = fh(t) then H [fh(t)] = f (t) The correct statements are

• A. (i) and (iv) only.
• B. (i) and (iii) only.
• C. (i), (ii) and (iii) only.
• D. All of these