1. What is the main function of (A/D) or ADC converter?

A. Converts Digital to Analog Signal

B. Converts Analog to Digital signal

C. All of the mentioned

D. None of the mentioned

2. What is the main function of (D/A. or DAC converter?

A. Converts Digital to Analog Signal

B. Converts Analog to Digital signal

C. All of the mentioned

D. None of the mentioned

3. The S/H is a digitally controlled analog circuit that tracks the analog input signal during the sample mode and then holds it fixed during the hold mode to the instantaneous value of the signal at the time the system is switched from the sample to the hold mode.

A. True

B. False

4. The time required to complete the conversion of Analog to Digital is ________ the duration of the hold mode of S/H.

A. Greater than

B. Equals to

C. Less than

D. Greater than or Equals to

5. In the A/D converter, what is the time relation between sampling period T and the duration of the sample mode and the hold mode?

A. Should be larger than the duration of sample mode and hold mode

B. Should be smaller than the duration of sample mode and hold mode

C. Should be equal to the duration of sample mode and hold mode

D. Should be larger than or equal to the duration of sample mode and hold mode

6. In the practical A/D converters, what are the distortions and time-related degradations that occur during the conversion process?

A. Jitter errors

B. Droops

C. Nonlinear variations in the duration of the sampling aperture

D. All of the mentioned

7. In the absence of an S/H, the input signal must change by more than one-half of the quantization step during the conversion, which may be an impractical constraint.

A. True

B. False

8. The noise power σn2 can be reduced by increasing the sampling rate to spread the quantization noise power over a larger frequency band (-Fs/2, Fs/2).

A. True

B. False

9. What is the process of down-sampling called?

A. Decimation

B. Fornication

C. Both Decimation & Fornication

D. None of the mentioned

10. If the interpolation factor is I = 256, the A/D converter output can be obtained by averaging successive non-overlapping blocks of 128 bits.

A. True

B. False

11. The crosshatched areas give two types of Quantization error in DM, they are?

A. Slope-overload distortion

B. Granular noise

C. Slope-overload distortion & Granular noise

D. None of the mentioned

12. The slope-overload distortion is avoided, if which of the following conditions satisfy?

A. Min|dx(t)/d(t)| ≤ Δ/T

B. Max|dx(t)/d(t)| ≤ Δ/T

C. |dx(t)/d(t)| ≤Δ/T

D. None of the mentioned

13. In DM, By increasing Δ, reduces the overload distortion but increases the granular noise, and vice versa.

A. True

B. False

14. Which of the following is the right way to reduce distortion in the DM?

A. By setting up an integrator in front of DM

B. By setting up an integrator behind the DM

C. By setting up an integrator in the middle of DM

D. None of the mentioned

15. What are the effects produced by Dm by setting up an integrator at the front of DM?

A. Simplifies the DM decoder

B. Increases correlation of the signal into the DM input

C. Emphasizes the low frequencies of x(t)

D. All of the mentioned

16. The frequency shift can be achieved by multiplying the bandpass signal as given in the equation x(t) = \(u_c (t) cos2π F_c t-u_s (t) sin2π F_c t\) by the quadrature carriers cos[2πFct] and sin[2πFct] and lowpass filtering the products to eliminate the signal components of 2Fc.

A. True

B. False

17. What is the final result obtained by substituting Fc=kB-B/2, T= 1/2B and say n = 2m i.e., for even and n=2m-1 for odd in equation x(nT)= \(u_c (nT)cos2πF_c nT-u_s (nT)sin 2πF_c nT\)?

A. \((-1)^m u_c (mT_1)-u_s\)

B. \(u_s (mT_1-\frac{T_1}{2})(-1)^{m+k+1}\)

C. \((-1)^m u_c (mT_1)- u_s (mT_1-\frac{T_1}{2})(-1)^{m+k+1}\)

D. None

18. Which low pass signal component occurs at the rate of B samples per second with even-numbered samples of x(t)?

A. uc-lowpass signal component

B. us-lowpass signal component

C. uc & us-lowpass signal component

D. none of the mentioned

19. Which low pass signal component occurs at the rate of B samples per second with odd-numbered samples of x(t)?

A. uc – lowpass signal component

B. us – lowpass signal component

C. uc & us – lowpass signal component

D. none of the mentioned

20. What is the reconstruction formula for the bandpass signal x(t) with samples taken at the rate of 2B samples per second?

A. \(\sum_{m=-\infty}^{\infty}x(mT)\frac{sin(π/2T) (t-mT)}{(π/2T)(t-mT)} cos2πF_c (t-mT)\)

B. \(\sum_{m=-\infty}^{\infty}x(mT)\frac{sin(π/2T) (t+mT)}{(π/2T)(t+mT)} cos2πF_c (t-mT)\)

C. \(\sum_{m=-\infty}^{\infty}x(mT)\frac{sin(π/2T) (t-mT)}{(π/2T)(t-mT)} cos2πF_c (t+mT)\)

D. \(\sum_{m=-\infty}^{\infty}x(mT)\frac{sin(π/2T) (t+mT)}{(π/2T)(t+mT)} cos2πF_c (t+mT)\)

21. What is the new center frequency for the increased bandwidth signal?

A. Fc‘= Fc+B/2+B’/2

B. Fc‘= Fc+B/2-B’/2

C. Fc‘= Fc-B/2-B’/2

D. None of the mentioned

22. According to the sampling theorem for low pass signals with T1=1/B, then what is the expression for uc(t) = ?

A. \(\sum_{m=-∞}^∞ u_c (mT_1)\frac{sin(\frac{π}{T_1}) (t-mT_1)}{(π/T_1)(t-mT_1)}\)

B. \(\sum_{m=-∞}^∞ u_s (mT_1-\frac{T_1}{2}) \frac{sin(\frac{π}{T_1}) (t-mT_1+T_1/2)}{(\frac{π}{T_1})(t-mT_1+\frac{T_1}{2})}\)

C. \(\sum_{m=-∞}^∞ u_c (mT_1)\frac{sin(\frac{π}{T_1}) (t+mT_1)}{(\frac{π}{T_1})(t+mT_1)}\)

D. \(\sum_{m=-∞}^∞ u_s (mT_1-\frac{T_1}{2}) \frac{sin(\frac{π}{T_1}) (t+mT_1+\frac{T_1}{2})}{(\frac{π}{T_1})(t+mT_1+\frac{T_1}{2})}\)

23. According to the sampling theorem for low pass signals with T1=1/B, then what is the expression for us(t) = ?

A. \(\sum_{m=-∞}^∞ u_c (mT_1) \frac{sin(\frac{π}{T_1}) (t-mT_1)}{(\frac{π}{T_1})(t-mT_1)}\)

B. \(\sum_{m=-∞}^∞ u_s (mT_1-\frac{T_1}{2}) \frac{sin(\frac{π}{T_1}) (t-mT_1+\frac{T_1}{2})}{(π/T_1)(t-mT_1+\frac{T_1}{2})}\)

C. \(\sum_{m=-∞}^∞ u_s (mT_1-\frac{T_1}{2}) \frac{sin(\frac{π}{T_1}) (t-mT_1-\frac{T_1}{2})}{(\frac{π}{T_1})(t-mT_1-\frac{T_1}{2})}\)

D. \(\sum_{m=-∞}^∞ u_c (mT_1) \frac{sin(\frac{π}{T_1}) (t+mT_1)}{(\frac{π}{T_1})(t+mT_1)}\)

24. What is the expression for low pass signal component uc(t) that can be expressed in terms of samples of the bandpass signal?

A. \(\sum_{n=-∞}^∞ (-1)^{n+r+1} x(2nT^{‘}-T^{‘}) \frac{sin(π/(2T^{‘})) (t-2nT^{‘}+T^{‘})}{(π/(2T^{‘}))(t-2nT^{‘}+T^{‘})}\)

B. \(\sum_{n=-∞}^∞ (-1)^n x(2nT^{‘}) \frac{sin(π/(2T^{‘})) (t-2nT^{‘})}{(π/(2T^{‘}))(t-2nT^{‘})}\)

C. All of the mentioned

D. None of the mentioned

25. What is the expression for low pass signal component us(t) that can be expressed in terms of samples of the bandpass signal?

A. \(\sum_{n=-∞}^∞ (-1)^{n+r+1} x(2nT^{‘}-T^{‘}) \frac{sin(π/(2T^{‘})) (t-2nT^{‘}+T^{‘})}{(π/(2T^{‘}))(t-2nT^{‘}+T^{‘})}\)

B. \(\sum_{n=-∞}^∞ (-1)^n x(2nT^{‘}) \frac{sin(π/(2T^{‘})) (t-2nT^{‘})}{(π/(2T^{‘}))(t-2nT^{‘})}\)

C. All of the mentioned

D. None of the mentioned