PART A – (10 x 2
= 20 Marks)
1.
What
is aliasing?
2.
States
sampling theorem for band limited signal and the filter to avoid aliasing.
3.
Write
the two fold effects of quantization process.
4.
Define
APF and APB.
5.
Write
the limitations of delta modulation
6.
What
is companding? Sketch the input, output characteristics of a compressor and
expander.
7.
What
are the advantages of delta modulation?
8.
What
is a linear predictor on what basis is the predictor coefficient determined.
9.
What
is the signal to noise ratio of PCM system if number of quantization level is 28?
10.
For
the uniform quantizer discuss the way in which the number of quantization level
influence the bandwidth and quantization noise?
PART
B-(5*16=80 Marks)
11.
Describe
the process of sampling and how the message signal is reconstructed from its
samples also illustrate the effect of aliasing with neat sketch. (16)
12.
Describe
PCM waveform coder and decoder with neat sketch and list the merits compare
with analog codes.
(16)
13.
i) Describe and illustrate delta modulation
and its quantization error. (8)
ii)
Explain how adaptive delta modulation performs better and gains more signal to
noise ratio then delta modulation.
(8)
14.
Illustrate
how the adaptive time domain coder the speech at low bit rate and compare it
with the frequency domain coder ADPCM. (16)
15.
i)The signal x(t) =4cos 400Î t+12cos 360Î t is
ideally sampled at a frequency of 300 samples per second. The sampled signal is
passed through a unit gain low pass filter with a cutoff frequency of 200 Hz
list the frequency components present at the output of the low pass filter.
(8)
ii) A delta modulator with the fixed step size
of 0.75 V is given a sinusoidal message signal. If the sampling frequency is 30
times of the nyquist rate, determine the maximum permissible amplitude of the
message signal if slope overload is to be avoided. (8)
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