Recent questions and answers in Electronics communication

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1 answer 66 views
1 answer 15 views

Which of the following statement is false? Modulation is used to: (1) Reduce the bandwidth used (2) Separate differing transmissions (3) Ensure that intelligence may be transmitted over long distances (4) Allow the use of practicable antennas

answered May 29, 2018 in Electronics communication
1 answer 17 views

Indicate which one of the following is NOT an advantage of FM over AM? (1) Better noise immunity is provided (2) Lower bandwidth is required (3) The transmitted power is more useful (4) Less modulating power is required 

answered May 29, 2018 in Electronics communication
1 answer 14 views

Theoretical bandwidth requirement for FM system is: (1) Same as that of the modulating signal bandwidth (2) Twice of modulating signal Bandwidth (3) Thrice as of modulating signal Bandwidth (4) Infinite 

answered May 29, 2018 in Electronics communication
1 answer 10 views

The Ku frequency band used in satellite communication (for uplink and downlink) is: (1) 14 GHz and 11 GHz (2) 30 GHz and 20 GHz (3) 70 GHz and 50 GHz (4) 60 GHz and 45 GHz 

answered May 29, 2018 in Electronics communication
1 answer 9 views

The disadvantage of CDMA system is: (1) Higher MAI with more user count. (2) That it needs least power consumption. (3) That it needs coherent signal. (4) That it is not suitable with PSK systems 

answered May 29, 2018 in Electronics communication
1 answer 21 views

Which of the following is an inherent property of an optical signal and cannot be eliminated even in principle? (1) Thermal noise (2) Shot noise (3) Environmental noise (4) Background Noise

answered May 29, 2018 in Electronics communication
1 answer 14 views

The use of non-uniform quantization leads to: (1) Reduction in transmission bandwidth. (2) Increase in maximum SNR. (3) Increase in SNR for signal levels. (4) Simplification of quantization process. 

answered May 29, 2018 in Electronics communication
1 answer 13 views

In amplitude modulation AM, if modulation index is more than 100% then: (1) Power of the wave increases. (2) Efficiency of transmission increases. (3) The wave gets distorted. (4) Bandwidth increases

answered May 29, 2018 in Electronics communication
1 answer 20 views

In the case of a 70–MHz IF carrier for a transponder bandwidth of 36 MHz, energy must lie between MHz: (1) 34 and 106 (2) 52 and 88 (3) 106 and 142 (4) 34 and 142

answered May 28, 2018 in Electronics communication
1 answer 11 views

In T1 digital system, the frame synchronization code repeats every

answered May 23, 2018 in Electronics communication
1 answer 13 views

In a PCM system the number of quantization level are 16 and the maximum signal frequency is 4 KHz the transmission bit rate is

answered May 23, 2018 in Electronics communication
1 answer 18 views

Principle of Doppler effect is used in

answered May 23, 2018 in Electronics communication
1 answer 5 views

The capacity of a standard 4 KHz telephone channel with a 32 dB SNR is

answered May 23, 2018 in Electronics communication
1 answer 11 views

A radio transmitter is an equipment:

answered May 22, 2018 in Electronics communication
1 answer 8 views

As the thermal noise get doubled due to the increase in a resistance the noise power get.  (A) doubled (B) quadruped (C) unchanged (D) halved.

answered May 17, 2018 in Electronics communication
1 answer 8 views

A two cavity klystron tube is a  (A) velocity modulated tube (B) frequency modulated tube (C) Amplitude modulated tube (D) simple triode

answered May 17, 2018 in Electronics communication
1 answer 7 views

Ionosphere layer of earth is situated at  (A) upto 18 kms from earth (B) from 18 to 70 km (C) 70 to 500 km (D) above 500 km

answered May 17, 2018 in Electronics communication
1 answer 7 views

Which wave cannot exist inside wave guide  (A) TE (B) TM (C) TEM (D) HE

answered May 17, 2018 in Electronics communication
1 answer 21 views

The frequency range 30MHz - 300MHz is  (A) medium frequency (B) very high frequency (C) super high frequency (D) Infrared frequency

answered May 17, 2018 in Electronics communication
1 answer 21 views

The most common device used for detection in radio receivers is   (A)amplifier (B) triode (C) diode (D) transistor

answered May 17, 2018 in Electronics communication
1 answer 11 views

In commercial FM broadcasting, the maximum frequency deviation is normally   (A) 5 KHz (B) 15 KHz (C) 75 KHz (D) 200 KHz

answered May 17, 2018 in Electronics communication
1 answer 13 views

When a dipole antenna of 1/8 length has an equivalent total resistance of 1.5 Watt then the efficiency of the antenna is   (A) 0.89159% (B) 8.9159% (C) 89.159% (D) 891.59%

answered May 17, 2018 in Electronics communication
1 answer 15 views

A two port network having a 6 dB loss will give  (A) an output power which is one - quarter of the input power (B) an output power which is one - half of the input power (C) an output voltage which is 0.707 of the input voltage. (D) an output power which is 0.707 of the input power.

answered May 17, 2018 in Electronics communication
1 answer 6 views

When a dominant mode wave guide not terminated in its characteristic impedance is excited with a 10 GHZ signal then if d is the distance between two successive minima of the standing wave in the guide then   (A) d = 1.5 cm (B) d is less then 1.5 cm (C) d is greater then 1.5 cm (D) d = 3 cm

answered May 17, 2018 in Electronics communication
1 answer 16 views

When an antenna of input resistance 73 ohm is connected to a 50-ohm line and if the losses are ignored then its efficiency will be nearly   (A) 0.19 (B) 0.81 (C) 0.97 (D) 1.19

answered May 17, 2018 in Electronics communication
1 answer 22 views

In a radio transmitter, the frequency of the crystal oscillator will be stable for a long time if the quality factor of the crystal resonator is  (a) > 100 (b) > 500 (c) > 1000 (d) > 20000

answered May 15, 2018 in Electronics communication
1 answer 11 views

QPSK system is superior to BPSK system because  (a) its bandwidth is higher than that of BPSK System (b) interchannel interference in QPSK system is less then that in BPSK system (c) bandwidth of QPSK system is half of the bandwidth of BPSK system (d) in QPSK system inter-symbol interference is improved

answered May 15, 2018 in Electronics communication
1 answer 9 views

A radio receiver is placed at one corner of a table and again placed at some other corner of the same table. Loudspeaker output is changed because  (a) image interference is reduced (b) adjacent channel interference is increased (c) of fading (d) line of sight propagation is not utilized

answered May 15, 2018 in Electronics communication
1 answer 12 views

Earth coverage dish antenna is used in satellite system. It is characterized by the fact that  (a) It is a narrow beam antenna (b) It is Parabolic antenna (c) it is sharply focused within a small area of the surface of the earth (d) it is a wide angle antenna which covers a large area of the surface of the earth

answered May 15, 2018 in Electronics communication
1 answer 14 views

A rectangular waveguide is 4.2 cm by 1.85 cm. The cut-off frequency of the dominant mode through this waveguide is  (a) 3.57 GHz (b) 3.75 GHz (c) 3.70 MHz (d) 3.57 MHz

answered May 15, 2018 in Electronics communication
1 answer 19 views

For an antenna to be frequency-independent, it should expand or contract in proportion to the  (a) gain (b) directivity (c) wavelength (d) impedance

answered May 15, 2018 in Electronics communication
1 answer 13 views

The frequency range of FM radio is

answered May 14, 2018 in Electronics communication
1 answer 12 views

The basic element of radio communication system which generates radio waves is  1. micro phone 2. transmitter 3.transmitting antenna 4. Loudspeaker 

answered May 13, 2018 in Electronics communication
1 answer 9 views

U.H.F. band covers the range of  1. 0-300 KHz 2. 3-30 MHz 3. 300-3000 KHz 4. 300 MHz - 3 GHz

answered May 13, 2018 in Electronics communication
1 answer 11 views

In the ideal closed loop operational amplifier, the gain depends on (A) value of the series component (B) value of the feedback component (C) on the operational amplifier itself (D) both A and B

answered May 12, 2018 in Electronics communication
1 answer 29 views

Noise is primarily a variation in (A) Amplitude (B) phase (C) frequency (D) none of the above

answered May 12, 2018 in Electronics communication
1 answer 14 views

A tuned circuit has a Q of 100 at its resonant frequency of 500 kHz. Its bandwidth is _____kHz. (A) 50000 (B) 0.2 (C) 600 (D) 5

answered May 12, 2018 in Electronics communication
1 answer 300 views

An amplitude modulation performs the mathematical operation of (A) Division (B) multiplication (C) subtraction (D) addition

answered May 12, 2018 in Electronics communication
0 answers 20 views

Go-stationary satellites are placed in equatorial orbits at the height approximately  a. 1000 km b. 15000 km 0. 25000 km d. 36000 km

asked Apr 9, 2018 in Electronics communication
0 answers 33 views

In satellite communication, scrambling is mainly used for -  A) I clock recovery B) encryption C) limiting power spectral density D) bandwidth efficiency

asked Apr 9, 2018 in Electronics communication
0 answers 17 views

In an axial mode operation of a helical antenna, maximum field radiated by the antenna is :  A) along the axis of the helical B) in a plane normal to the helix antenna axis C) in both axial and normal planes D) None of the above

asked Apr 9, 2018 in Electronics communication
0 answers 14 views

Which modulation scheme would you suggest for high speed data transmission over a fading channel?  A) MSK B) BPSK C) FSK D) OFDM

asked Apr 9, 2018 in Electronics communication
0 answers 309 views

The difference of the reference input and the actual output signal is called  (a) error signal (b) controlling signal (c) actuating signal (d) transfer function

asked Apr 9, 2018 in Electronics communication
0 answers 14 views

In a PID controller,the values of proportional, integral and derivative are dependent on  (a) future, past and present errors respectively (b) present, past and future errors respectively (c) past, present and future errors respectively (d) present, future and past errors respectively

asked Apr 9, 2018 in Electronics communication
0 answers 45 views

The signal is extended from 96KHz to 100KHz, so the minimum sampling frequency required is  (a) 8KHz (b) 200KHz (c) 4KHz (d) 100KHz

asked Apr 9, 2018 in Electronics communication
0 answers 8 views

A differentiation circuit has a  (a) very high time constant (b) very low time constant (c) infinite time constant (d) zero time constant

asked Apr 9, 2018 in Electronics communication
0 answers 38 views

Ideally Voltage Standing Wave Ratio (VSWR) should be  (a) as large as possible (b) as small as possible (c) as close to unity as possible (d) infinity

asked Apr 9, 2018 in Electronics communication
0 answers 13 views

Following is/are a property/properties of quantization  (a) it is an nonlinear process (b) it is an irreversible process (c) it maps a larger set of input values to a smaller set  (d) all of these 

asked Apr 9, 2018 in Electronics communication
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