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  1. A signal m(t) band-limited to 3 kHz is sampled at a rate
    33
    1
    %
    3
    higher than the Nyquist rate. The max acceptable error in the sample amplitude (max. quantization error) is 0.5% of peak amplitude Vp. The quantized samples are binary coded. Find out the minimum bandwidth required to transmit the encoded binary signal. If 24 such signals are TDM, determine the minimum bandwidth required to transmit the multiplexed signal—
    1. 1536 kHz
    2. 768 kHz
    3. 472 kHz
    4. 1344 kHz
Correct Option: B

We know that minimum bandwidth required to transmit 24 channel through TDM (Time Division Multiplexing)

= nN
fs
2

Where, N = no. of bits
n = no. of channel
fs = sampling frequency
According to question,
fs = 33% greater that the Nyquist rate
= 1 +
1
.2.fm
3

or
fs =
4
×2×3kHz = 8kHz
3

For the quantization step size δ the maximum quantization error is ± δ/2 and given as δ/2 = 0·5% of Vp
or
1
2Vp
=
0.5
.Vp
2L100

Where,
δ =
2Vp
L

Vp = maximum amplitude
L = no. of level = 2n
N > 7 i.e. for binary coding we must take N = 8
Now,
BTmin = N.n.
fs
2

=
8 × 24 × 8
kHz = 768 kHz
2



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