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Communications MCQ Set 1

1. INTELSAT II and III operates their TWTA in
a) Saturation region
b) Linear region
c) Hard limiting region
d) None of the mentioned

View Answer

Answer: b [Reason:] INTELSAT II and III operates its traveling wave tube amplifiers in linear region.

2. As the number of carriers, the capacity of transponder
a) Increases
b) Decreases
c) Remains the same
d) None of the mentioned

View Answer

Answer: b [Reason:] The capacity of the transponder drops as the number of carriers increases.

3. As the number of carriers increases, the number of guard bands
a) Increases
b) Decreases
c) Remains the same
d) None of the mentioned

View Answer

Answer: a [Reason:] Guard bands are needed between the carriers. Thus as carriers increases, guard bands are also increases.

4. TWTA which operates in the linear region
a) Reduces interference
b) Provide less overall power
c) Is power limited
d) All of the mentioned

View Answer

Answer: d [Reason:] TWTA operating in linear region reduces interference, and can provide less overall power. The channel becomes power limited and can service fewer carriers.

5. Which method is better when traffic is heavy?
a) SPADE
b) Binary tree search
c) SPADE & Binary tree search
d) None of the mentioned

View Answer

Answer: c [Reason:] SPADE operation and binary tree search can be used when the traffic is heavy.

6. SPADE uses
a) QPSK
b) BPSK
c) FSK
d) MSK

View Answer

Answer: a [Reason:] SPADE uses digital voice transmission – QPSK.

7. SPADE is a
a) MAA system
b) DAMA system
c) MAA & DAMA system
d) None of the mentioned

View Answer

Answer: b [Reason:] SPADE is a DAMA system where all channels are shared.

8. In SPADE system, the carrier is done based on
a) Fixed assignment
b) Demand assignment
c) Fixed & Demand assignment
d) None of the mentioned

View Answer

Answer: b [Reason:] In SPADE system, the carrier is assigned dynamically, that is on demand.

9.Which is more costlier?
a) TDMA
b) FDMA
c) ALOHA
d) None of the mentioned

View Answer

Answer: a [Reason:] TDMA earth station equipment is more costlier than the FDMA equipments.

10. Which technique needs precise synchronization?
a) TDMA
b) FDMA
c) TDMA & FDMA
d) None of the mentioned

View Answer

Answer: a [Reason:] TDMA operation needs very precise synchronization needed to assure orthogonality of time slots.

Communications MCQ Set 2

1. Interpolation is done by
a) Curve fitting
b) Regression analysis
c) Curve fitting & Regression analysis
d) None of the mentioned

View Answer

Answer: c [Reason:] Interpolating the value requires or is done by curve fitting and regression analysis.

2. Interpolation provides a mean for estimating functions
a) At the beginning points
b) At the ending points
c) At the intermediate points
d) None of the mentioned

View Answer

Answer: c [Reason:] Interpolation provides a mean for estimating the function at the intermediate points.

3. Interpolation methods are
a) Linear interpolation
b) Piecewise constant interpolation
c) Polynomial interpolation
d) All of the mentioned

View Answer

Answer: d [Reason:] Some of the interpolation techniques are linear interpolation, piecewise constant interpolation, polynomial interpolation, spline interpolation etc.

4. Linear interpolation is
a) Easy
b) Precise
c) Easy & Precise
d) None of the mentioned

View Answer

Answer: a [Reason:] Linear interpolation is quick and easy but not precise.

5. Error is equal to
a) Distance between the data points
b) Square of the distance between the data points
c) Half the distance between the data points
d) None of the mentioned

View Answer

Answer: b [Reason:] Error is equal to square of the distance between the data points.

6. Which produces smoother interpolants?
a) Polynomial interpolation
b) Spline interpolation
c) Polynomial & Spline interpolation
d) None of the mentioned

View Answer

Answer: c [Reason:] Polynomial interpolation and spline interpolation produces smoother interpolants.

7. Which is more expensive?
a) Polynomial interpolation
b) Linear interpolation
c) Polynomial & Linear interpolation
d) None of the mentioned

View Answer

Answer: a [Reason:] Polynomial interpolation is more expensive than linear interpolation.

8. Gaussian process is a _____ interpolation process.
a) Linear
b) Non linear
c) Not an interpolation process
d) None of the mentioned

View Answer

Answer: a [Reason:] Gaussian process is a non linear interpolation process.

9. Interpolation means
a) Adding new data points
b) Only aligning old data points
c) Only removing old data points
d) None of the mentioned

View Answer

Answer: a [Reason:] Interpolation is a method of adding new data points within the range of a discrete set of known data points.

10. Interpolation is a method of
a) Interrelating
b) Estimating
c) Integrating
d) Combining

View Answer

Answer: b [Reason:] Interpolation is a method of estimating the value of the function.

Communications MCQ Set 3

1. The method in which the tail of one pulse smears into adjacent symbol interval is called as
a) Intersymbol interference
b) Interbit interference
c) Interchannel interference
d) None of the mentioned

View Answer

Answer: a [Reason:] Due to the effect of system filtering the received pulse can overlap on one and another. The tail of one pulse smears into adjacent symbol interval thereby interfering the detection process. This process is called as intersymbol interference.

2. If each pulse of the sequence to be detected is in _____ shape, the pulse can be detected without ISI.
a) Sine
b) Cosine
c) Sinc
d) None of the mentioned

View Answer

Answer: c [Reason:] The sinc shaped pulse is the ideal nyquist pulse. If each pulse in the sequence to be detected is in sinc shape the pulses can be detected without ISI.

3. What is symbol rate packing?
a) Maximum possible symbol transmission rate
b) Maximum possible symbol receiving rate
c) Maximum bandwidth
d) Maximum ISI value allowed

View Answer

Answer: a [Reason:] A system with bandwidth Rs/2 can support a maximum transmission rate of Rs without ISI. Thus for ideal Nyquist filtering the maximum possible symbol transmission rate is called as symbol rate packing and it is equal to 2 symbols/s/Hz.

4. A nyquist pulse is the one which can be represented by _____ shaped pulse multiplied by another time function.
a) Sine
b) Cosine
c) Sinc
d) None of the mentioned

View Answer

Answer: c [Reason:] A nyquist filter is one whose frequency transfer function can be represented by a rectangular function convolved with any real even symmetric frequency function and a nyquist pulse is one whose shape can be represented by sinc function multiplied by another time function.

5. Examples of nyquist filters are
a) Root raised cosine filter
b) Raised cosine filter
c) Root raised & Raised cosine filter
d) None of the mentioned

View Answer

Answer: c [Reason:] The most popular among the class of nyquist filters are raised cosine and root raised cosine filter.

6. The minimum nyquist bandwidth for the rectangular spectrum in raised cosine filter is
a) 2T
b) 1/2T
c) T2
d) 2/T

View Answer

Answer: b [Reason:] For raised cosine spectrum the minimum nyquist bandwidth is equal to 1/2T.

7. Roll off factor is the fraction of
a) Excess bandwidth and absolute bandwidth
b) Excess bandwidth and minimum nyquist bandwidth
c) Absolute bandwidth and minimum nyquist bandwidth
d) None of the mentioned

View Answer

Answer: b [Reason:] The roll off factor is defined by fraction of excess bandwidth and the minimum nyquist bandwith. It ranges from 0 to 1.

8. Which value of r ( roll off factor) is considered as Nyquist minimum bandwidth case?
a) 0
b) 1
c) Infinity
d) None of the mentioned

View Answer

Answer: a [Reason:] For the roll off factor of 0 an ideal rectangular nyquist pulse is obtained. This is called as nyquist minimum bandwidth case.

9. A pulse shaping filter should satisfy two requirements. They are
a) Should be realizable
b) Should have proper roll off factor
c) Both of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] A pulse shaping filter should provide the desired roll off and should be realizable, that is the impulse response needs to be truncated to a finite length.

10. Examples of double side band signals are
a) ASK
b) PSK
c) ASK & PSK
d) None of the mentioned

View Answer

Answer: c [Reason:] ASK and PSK needs twice the transmission bandwidth of equivalent baseband signals. Thus these are called as double side band signals.

Communications MCQ Set 4

1. ISDN integrates speech and data on
a) Different lines
b) Same lines
c) Different & Same lines
d) None of the mentioned

View Answer

Answer: b [Reason:] Integrated services for digital domain integrates speech and data signals on the same lines.

2. ISDN is a
a) Packet switched network
b) Circuit switched telephone network
c) Both of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] ISDN is a circuit switched telephone network which also provides access to packet switched network.

3. Circuit switched connection is provided for
a) Voice
b) Data
c) Voice & Data
d) None of the mentioned

View Answer

Answer: c [Reason:] Circuit switched connection can be provided for either voice or data.

4. Packet switched connection is provided for
a) Voice
b) Data
c) Voice & Data
d) None of the mentioned

View Answer

Answer: b [Reason:] Packet switched connection can be provided only for data.

5. Channel bonding provides
a) Higher data rate
b) Lower data rate
c) Does not affect data rate
d) None of the mentioned

View Answer

Answer: a [Reason:] Channel bonding can achieve higher data rate.

6. U-interface is the two wire interface between
a) Computing device and terminal adapter
b) Terminal adapter and exchange unit
c) Exchange unit and network terminating unit
d) Computing device and exchange unit

View Answer

Answer: c [Reason:] U-interface is the two wire connection or interface between exchange unit and network terminating unit.

7. T interface is the serial interface between
a) Computing device and terminal adapter
b) Terminal adapter and exchange unit
c) Exchange unit and network terminating unit
d) Computing device and exchange unit

View Answer

Answer: a [Reason:] T interface is the serial interface between computing device and terminal adapter.

8. S-interface is a _______ bus.
a) Two wire bus
b) Four wire bus
c) Single wired bus
d) None of the mentioned

View Answer

Answer: b [Reason:] The S interface is a four wire bus that ISDN consumer devices plug into.

9. The services provided by ISDN
a) Bearer service
b) Teleservice
c) Secondary service
d) All of the mentioned

View Answer

Answer: d [Reason:] The services provided by ISDN and classified by attributes are bearer service, teleservice and secondary service.

10. Attributes of ISDN have
a) Definition
b) Allowable values
c) Definition & Allowable values
d) None of the mentioned

View Answer

Answer: c [Reason:] ISDN services are characterized by attributes and attributes have definition and allowable values.

Communications MCQ Set 5

1. Link budget consists of calculation of
a) Useful signal power
b) Interfering noise power
c) Useful signal & Interfering noise power
d) None of the mentioned

View Answer

Answer: c [Reason:] The link analysis and its output, the link budget consists of calculations and tabulations of useful signal power and interfering noise power at the receiver.

2. Link budget can help in predicting
a) Equipment weight and size
b) Technical risk
c) Prime power requirements
d) All of the mentioned

View Answer

Answer: d [Reason:] Link budget can help to predict equipment weight, size, prime power requirements, technical risk and cost. Link budget is one of the system manager’s useful document.

3. Which is the primary cost for degradation of error performance?
a) Loss in signal to noise ratio
b) Signal distortion
c) Both of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] There are two primary causes for degradation of error performance. They are loss in signal to noise ratio and the second is signal distortion caused by intersymbol interference.

4. Which factor adds phase noise to the signal?
a) Jitter
b) Phase fluctuations
c) Jitter & Phase fluctuations
d) None of the mentioned

View Answer

Answer: c [Reason:] When a local oscillator is used in signal mixing, phase fluctuations and jitter adds phase noise to the signal.

5. Antennas are used
a) As transducer
b) To focus
c) Both of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] Antennas are used as transducer that convert electronic signals to electromagnetic fields and vice versa. They are also used to focus the electromagnetic energy in the desired direction.

6. Mechanism contributing to reduction in efficiency is called as
a) Amplitude tapering
b) Blockage
c) Edge diffraction
d) All of the mentioned

View Answer

Answer: d [Reason:] Mechanism contributing to reduction in efficiency is called as amplitude tapering, spillover, edge diffraction, blockage, scattering, re-radiation and dissipative loss.

7. Space loss occurs due to decrease in
a) Electric field strength
b) Efficiency
c) Phase
d) Signal power

View Answer

Answer: a [Reason:] Due to decrease in electric field strength there will be a decrease in signal strength as a function of distance. This is called as space loss.

8. Antenna’s efficiency is given by the ratio of
a) Effective aperture to physical aperture
b) Physical aperture to effective aperture
c) Signal power to noise power
d) Losses

View Answer

Answer: a [Reason:] The larger the antenna aperture the larger is the resulting signal power density in the desired direction. The ratio of effective aperture to physical aperture is the antenna’s efficiency.

9. Effective radiated power of an isotropic radiator can be given as product of
a) Radiated power and received power
b) Effective area and physical area
c) Transmitted power and transmitting gain
d) Receiving power and receiving gain

View Answer

Answer: c [Reason:] An effective radiated power with respect to an isotropic radiator EIRP can be defined as the product of transmitted power and the gain of the transmitting antenna.

10. According to reciprocity theorem, _____ and _____ are identical.
a) Transmitting power and receiving power
b) Transmitting gain and receiving gain
c) Effective area and physical area
d) None of the mentioned

View Answer

Answer: b [Reason:] The reciprocity theorem states that for a given antenna and carrier wavelength the transmitting and receiving gain are identical.