A2D and D2A Converters

Digital Communications Systems

This set of Digital Signal Processing Multiple Choice Questions & Answers (MCQs) focuses on “A2D and D2A Converters”.

1. Which of the following should be done in order to convert a continuous-time signal to a discrete-time signal?
a) Sampling
b) Differentiating
c) Integrating
d) None of the mentioned

2. The process of converting discrete-time continuous valued signal into discrete-time discrete valued (digital) signal is known as ____________
a) Sampling
b) Quantization
c) Coding
d) None of the mentioned

3. The difference between the unquantized x(n) and quantized xq(n) is known as ___________
a) Quantization coefficient
b) Quantization ratio
c) Quantization factor
d) Quantization error

4. Which of the following is a digital-to-analog conversion process?
a) Staircase approximation
b) Linear interpolation
c) Quadratic interpolation
d) All of the mentioned

5. The relation between analog frequency ‘F’ and digital frequency ‘f’ is?
a) F=f*T(where T is sampling period)
b) f=F*T
c) No relation
d) None of the mentioned

6. What is output signal when a signal x(t)=cos(2*pi*40*t) is sampled with a sampling frequency of 20Hz?
a) cos(pi*n)
b) cos(2*pi*n)
c) cos(4*pi*n)
d) cos(8*pi*n)

7. If ‘F’ is the frequency of the analog signal, then what is the minimum sampling rate required to avoid aliasing?
a) F
b) 2F
c) 3F
d) 4F

8. What is the nyquist rate of the signal x(t)=3cos(50*pi*t)+10sin(300*pi*t)-cos(100*pi*t)?
a) 50Hz
b) 100Hz
c) 200Hz
d) 300Hz

9. What is the discrete-time signal obtained after sampling the analog signal x(t)=cos(2000*pi*t)+sin(5000*pi*t) at a sampling rate of 5000 samples/sec?
a) cos(2.5*pi*n)+sin(pi*n)
b) cos(0.4*pi*n)+sin(pi*n)
c) cos(2000*pi*n)+sin(5000*pi*n)
d) none of the mentioned

10. If the sampling rate Fs satisfies the sampling theorem, then the relation between quantization errors of analog signal(eq(t)) and discrete-time signal(eq(n)) is?
a) eq(t)=eq(n)
b) eq(t)<eq(n)
c) eq(t)>eq(n)
d) not related

11. The quality of output signal from A/D converter is measured in terms of ___________
a) Quantization error
b) Quantization to signal noise ratio
c) Signal to quantization noise ratio
d) Conversion constant

12. Which bit coder is required to code a signal with 16 levels?
a) 8 bit
b) 4 bit
c) 2 bit
d) 1 bit

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