Q161
Open questionA carrier is modulated by a digital bit stream having one of the possible phases of 0°, 90°, 180° and 270°. Then the modulation is termed as
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Digital Communication
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Q162
Open questionThe different access methods which permit many satellite users to operate in parallel through a single transponder without interfering with each other are
1. Frequency Division Multiple Access (FDMA)
2. Time Division Multiple Access (TDMA)
3. Code Division Multiple Access (CDMA)
Which of the above are correct?
1. Frequency Division Multiple Access (FDMA)
2. Time Division Multiple Access (TDMA)
3. Code Division Multiple Access (CDMA)
Which of the above are correct?
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Q163
Open questionThe signal to noise ratio in telemetry should be
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Q164
Open questionFour signals m1(t) = cos(ω0t), m2(t) = 0.5cos(ω0t), m3(t) = 2cos(ω0t) and m4(t) = cos(4ω0t) are multiplexed by time division multiplexing system. The commutator speed is
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Q165
Open questionFor a binary FSK signal with a mark frequency of 49 kHz, a space frequency of 51 kHz and an input bit rate of 2 kbps, the peak frequency deviation will be
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Q166
Open questionA single bit, equally likely to be 0 and 1, is to be sent across an additive white Gaussian noise (AWGN) channel with power spectral density N0/2. Binary signaling, with 0 → p(t) and 1 → q(t), is used for the transmission, along with an optimal receiver that minimizes the bit-error probability.
Let ϕ1(t), ϕ2(t), form an orthonormal signal set. If we choose p(t) = ϕ1(t) and q(t) = -ϕ1(t), we would obtain a certain bit-error probability Pb. If we keep p(t) = ϕ1(t), but take q(t) = ϕ2(t), for what value of E would we obtain the same bit-error probability Pb?
Let ϕ1(t), ϕ2(t), form an orthonormal signal set. If we choose p(t) = ϕ1(t) and q(t) = -ϕ1(t), we would obtain a certain bit-error probability Pb. If we keep p(t) = ϕ1(t), but take q(t) = ϕ2(t), for what value of E would we obtain the same bit-error probability Pb?
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Q167
Open questionIn PCM, the signal-to-quantisation noise ratio for a sinusoidal signal quantized using 10-bit PCM is:
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Q168
Open questionSix message signals, each of bandwidth 5 KHz, are time-division-multiplexed and transmitted. The signaling rate and minimum channel bandwidth to avoid cross-talk in TDM, respectively, are:
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Q169
Open questionEye pattern is
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Q170
Open questionMatch List-I with List-II and select the correct answer using the options given below-
| List-I | List-II |
| a. Huffman | 1. Elimination of redundancy |
| b. Error correcting | 2. Reduces bit rate |
| c. NRZ-coding | 3. Adapts the transmitted signal to the line |
| d. Delta modulation | 4. Channel coding |
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Q171
Open questionOne of the following bandpass digital modulation schemes is not suitable for transmission over nonlinear bandpass channels:
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Q172
Open questionA signal of maximum frequency of 2 MHz modulated by 4 GHz carrier is DSB/SC. If the resultant signal is sampled ideally as low pass signal, the minimum sampling frequency should be
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Q173
Open questionConsider a binary transmission system with the symbol waveforms s1(t) = Acos(ωct), s2(t) = -Acos(ωct). This modulation format is termed as
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Q174
Open questionIn PCM system, if quantization level is increased from 2 to 4, then the relative bandwidth required will . . . . . . . .
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Q175
Open questionSource encoding in a data communication system is done in order to
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Q176
Open questionThe probability of error is minimum for
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Q177
Open questionIn FSK the carrier frequency is switched between . . . . . . . . extremes.
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Q178
Open questionBandwidth (BW) of 8PSK, 16PSK modulated signals are
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Q179
Open questionThe ramp signal m(t) = at is applied to a delta modulator with sampling period Ts and step size δ. Slope overload distortion would occur if
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Q180
Open questionA speech signal occupying the bandwidth of 300 Hz to 3 kHz is converted into PCM format for use in digital communication. If the sampling frequency is 8 kHz and each sample quantized into 256 levels, then the output bit rate will be
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