Components of the Time Frequency Analysis Method Questions

a. The input signal to a LTI system is 2cos(0.2t), which of the following cannot be a possible
output?
(i) 2cos(0.1t); (ii) 2cos(0.2t); (iii) 0.2cos(0.2t+41
o
) ; (iv) 0

b. Which of the following function does the operation y[n]=(x[n]+x[n-1])/4 perform?
(i) high pass; (ii) low pass; (iii) band pass; (iv) band stop

c. “10” in a 10-20 EEG system refers to
(i) The total number of electrodes in the EEG system; (ii) the relative distance between two
adjacent electrodes; (iii) voltage used by the system

d. The time-frequency analysis method is most useful when the time domain data (select all that
apply)
(i) is stationary without noise; (ii) is non-stationary without noise; (iii) contains abrupt
changes; (iv) is stationary and noisy; (v) is non-stationary and noisy
e. After you sample x(t) at 1 KHz for a duration of 2 seconds to get 2000 samples, you perform
XFT=fft(x) for the 2000 samples. Which of the following are the exact frequencies that XFT is
computed at (circle all the correct answers)
(i) 0.25 Hz; (ii) 0.5 Hz; (iii) 0.75 Hz; (iv) 0 Hz

f. If you do a synchronized average of 25 heart beats to obtain an averaged ECG, the noise
amplitude of the average is x times that of the original noise. The value for x is expected to
be:
(i) 0.1; (ii) 0.2; (iii) 0.25; (iv) 0.04;