Tde 1

Page 1

1 1. The Short Time Fourier Transform of a quasi-periodic stationary signal exibits:  horizontal lines ✔ o vertical lines o none of the other o diagonal lines 2. Which is the method providing the lowest excitation frequency in the study of frequency response function? o non of the other o the impact hammer o the hydraulic actuator  the piezzoelectric patch or shaker ✕ 3. The CPDF curve of a gaussian distribution o is larger than the signal RMS o none of the other  is nondimensional ✔ o is smaller than the signal RMS 4. The cross-correlation at tau = 3 between the signal X = [0; 0; 0; 1; 1; 1; 1; 0; 0; 0 ] and Y= [0; 0; 0; 1; 2; 2; 1; 0; 0; 0] is; o 1/3 o 0  1/7 ✔ o 2/7 2 5. A purely harmonic signal has a frequency of 10.51 Hz with amplitude 4 V, the signal is acquired with an accelerometer with full-scale range of ± 10 V. The ADC used for the acquisition has a fsamp of 20 Hz. A configuration that allows to correctly reconstruct the amplitude of the spectral component is: o none of the other o number of samples = 40. Rectangular window o number of samples = 40. Hanning window  number of samples = 200. Hanning window ✕ 6. Said B the number of bits of a converter, the LSB: o decreases when the converter range increases o does not depend on B o increases when B increases, but also depends on Vmax and Vmin  decreases when B increases ✔ 7. Describe the spectral leakage using the convolution theorem, in less than 10 lines. 8. The minimum number of bits to sample correctly a signal with maximum amplitude of 5 mV is: o 16  12 ✕ o 24 o none of the other 3 9. The RMS of a sine wave with amplitude ± 1 V is:  0.707 V ✔ o None of the other o 2 / 2(sqrt(3)) V o 1.414 V 10. Which is the method providing the largest excitation force (load) in the study of frequency response…