# Role of Students

Topics: Modulation, Phase-shift keying, Frequency-shift keying Pages: 4 (859 words) Published: August 2, 2013
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Labs in odd semester

Communication Systems & CircuitsVth Semester
Digital Communication IVth Semester

Question Bank

ECE/EEE Department
Guru Tegh Bahadur Institute of Technology

QUESTIONS:

C.R.O.

1. What is the purpose of the grid, and X&Y-plates?
2. For a certain ac input signal, if the Volt/Div knob is set to alower value, what effect does this have on the size of the signal on the screen?
3. The X-mag button magnifies the signal horizontally; is this button used for high or low frequency signal? Why?
4. What is the physical meaning of the root-mean-square value of an ac signal?

Sampling and Quantization

1. What do you mean by sampling period and sampling rate? 2. What is guard band?
3. What is Aperture effect?
4. What is aliasing?
5. The aperture effect in flat top pulses is reduced by using an a. Predictor
b. Integrator
c. Equalizer
d. Compander
6. The Nyquist rate of sampling for the signal x(t) = sinc(200t) +sinc2(200t) is a. 200
b. 400
c. 300
d. 250
7. The Nyquist Sampling rate for a signal band limited to 4KHz is a. 4KHz
b. 8KHz
c. 2KHz
d. 16KHz
8. Prior to sampling a ____________ is used to attenuate the high frequency components of the signal that lie outside the band of interest. 9. The sampled wave in practical system consists of __________ and ____________ rather than impulses. 10. What are the different types of sampling? Discuss.

Pulse Code Modulation
1. By what amount signal strength of human speech can vary with same speaker? 2. What is a crest factor?
3. Explain granular Noise.
4. Companding is used
a) To overcome quantizing noise in PCM
b) To allow amplitude limiting in the receiver
c) To protect small signals in PCM from quantization distortion. d) To...