An analog signal has a constant magnitude spectrum upto 4KHz.After 4KHz, the spectrum attenuates at 15dB/octave. Sketch thespectrum.
a. Case 1:The signal goes through a system with an ideal antialiasing LP filter, with sampling rate at 8KHz. Sketch the spectrumof the signal after passing it through such a filter. Use kHz atthe unit of x axis. Note the periodicity and conjugate symmetry ofthe spectrum.
b. Case 2: There is no anti aliasing filter, so we decide tosample at 12KHz. Sketch the spectrum and mark the amount ofaliasing by shading the area. Use kHz at the unit of x axis. Notethe periodicity and conjugate symmetry of the spectrum.
c. In case 2, we wish to suppress the aliased components(between 4k and 6k) by more than 50 dB. What should the maximumattenuation level at the edge of stop band be for such afilter?