UGC-NET 2017: Communication Systems SpeedTest Quiz 14

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Question 1

In time division multiplexing

• A Time is doubled between bits of a byte
• B Time slicing at CPU level takes place
• C Total time available is the channel is divided between several users and each users is allotted a time slice
• D None of the above

Question 2

For a parallel RC circuit, as shown in the figure, R = 20 Q and C = 0.9 pF, which is to be matched to 50 Q over a bandwidth,


The circuit has to be matched over 6 GHz to 18 GHz. What is the very best τ that can be achieved:

• A0
• B0.5
• C0.1
• D1

Question 3

The minimum input signal that gives output signal to noise ratio of 10 dB in a system that has an input impedance equal to 50, a noise figure of 4 dB and bandwidth of 100 KHz is:
[10.log (kT_o) = -174 dBm]

• A0.32 μV
• B1.41 μV
• C0.245 μV
• DNone of the above

Question 4

The min. step-size required for a Delta-modulator operating at 32 K sample/sec to track the signal (here u(t) is the n unit fx^–)
X(t) = 125t (u(t)-u(t-1)) + (250-125t) (u(t-1) – u(t-2))
So that slope overload is avoided, would be

• A2^–10
• B2^–8
• C2^–6
• D2^–4

Question 5

A DS/BPSK spread spectrum signal has a process gain of 500. If the desired error probability is 10^–5 and (E_b/J₀) required to obtain an error probability of 10^–5 for binary PSK is 9.5 dB, then the Jamming margin against a containers tone jammer is

• A23.6 dB
• B17.5 dB
• C117.4 dB
• D109 dB

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