Provided the analog signal
x(t)=5cos(4000pi t) + 2cos(7500 pi t )+3cos(1000pi t), for t>=0
sampled at the rate of 9,000Hz.
i) Sketch spectrums for range from 0Hz to 25000Hz. Ensure to labele frequencies.
ii) Plot recovered analog signal spectrum if ideal lowpass filter with the cutoff frequency of 4.5 khz is used to filter sampled signal.
iii) Find which frequency(ies) will be aliased one(s). Describe.