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Correct answer is (b) SINGLE SIDE Band

To elaborate: SSB STANDS for Single Side band. In SSB-SC (Single Side Band Suppressed Carrier), the carrier is suppressed and only either of the two sidebands is TRANSMITTED. This reduces power consumption and also lessens the BANDWIDTH.

Right answer is (a) True

To EXPLAIN: It is CORRECT statement that a ribbon MICROPHONE has bidirectional feature. Other microphones such as carbon, condenser etc does not have a bidirectional feature.

Right answer is (b) False

The explanation: All antennas can be used as TRANSMITTER and receiver both. Antenna transmits or receives electromagnetic WAVES only. Transmitter antenna MODULATES the MESSAGE signals and transmits the modulated waves and Receiver antenna receives the modulated wave and demodulates it.

Right answer is (a) True

For explanation I would say: TM stands for Transpositional Modulation. In TM, the message signal is modulated by inserting INFLECTIONS in the original waveform. The waveform is MODIFIED resulting in a modulated. TM is a pseudo analog modulation. In TM CARRIER also carries a PHASE VARIABLE.

Right answer is (a) 1

Best explanation: In NBFM, the modulation index is less than or close to unity. It is similar to Amplitude modulation EXCEPT a 180 degree phase SHIFT at the LOWER sideband.

The correct choice is (a) pulse-position modulation

Easy explanation: PPM is used for both analog and digital signals. In PPM, when a single pulse is transmitted in the ALLOTTED time shift, the message bits GET encoded. It is mostly used for optical COMMUNICATION such as OPTIC FIBER.

Right answer is (a) True

Explanation: CVSDM stands for continuously variable slope delta modulation. It can also be SEEN as delta modulation having variable STEP SIZE. Delta modulation involves analog to digital CONVERSION and vice-versa for the transmission of voice signals.

The correct option is (a) True

Explanation: It is a correct statement that NBFM stands for Narrow Band Frequency Modulation. In NBFM, the modulation index is less than or CLOSE to unity. It is similar to Amplitude modulation EXCEPT a 180 DEGREE PHASE shift at the lower sideband.

Correct answer is (a) balanced modulator

The best explanation: In SSB-SC transmitter, a balanced modulator is more LIKELY to be found in order to suppress the CARRIER, after which the result is passed through a band-pass FILTER in order to transmit the SELECTED sideband.

Correct choice is (a) True

To explain: RF is an electromagnetic wave frequencies in the range 3 KHz to 300 GHz. RF section of radio consists of oscillator so as to PROVIDE the necessary FREQUENCY for MIXING and it consists of a BUFFER stage for preventing the damage of signal source.

Right answer is (b) 20 KHz

Explanation: Audio SPECTRUM ranges from 20Hz to 20KHz and the frequency band for audio modulation ranges from 88MHzto 108 MHZ.

The correct option is (c) Frequency Shift Keying

To ELABORATE: FSK (Frequency Shift Keying) is a method used to transmit binary data in FORM of digital signals. It is MAINLY used for telegraphy. In telegraphy, a modem is used to convert binary data to FSK and vice-versa, for the communication between COMPUTERS and over telephone lines.

The correct option is (c) 3

To explain: The general expression for FM is as FOLLOWS:

FM (t) = AC sin (2πfct + βsin(2πfmt)), where β is the modulation index.

Thus β = 3.

Correct choice is (a) True

The explanation is: All antennas can be USED as transmitter and receiver both. Antenna transmits or receives electromagnetic WAVES only. Transmitter antenna MODULATES the message SIGNALS and transmits the modulated waves and Receiver antenna receives the modulated wave and demodulates it.

Right answer is (d) modular section and visual exciter can be solid state devices

To explain I would SAY: Advantages of IF modulation is that the modular section and visual exciter can be solid state devices. Its other advantages are it can USE VSB FILTER that can be introduced at low POWER level. Moreover it is ECONOMICAL.

Correct choice is (b) False

To explain: In tape recorders, only CONE TYPE loudspeakers can be used. It does not work WELL with horn type loudspeakers.

Correct choice is (b) False

The BEST explanation: Vestigial Sideband Modulation (VSB) is a type of amplitude modulation in which the carrier and only one sideband is completely transmitted and the other sideband is partly transmitted. THUS, television PRODUCTION is DONE using VSB modulation as it reduces bandwidth to half.

Right option is (a) Circular polarization

The EXPLANATION: In circular polarization at each point the electric field of electromagnetic wave has a constant MAGNITUDE but its direction changes as it ROTATES with time at a steady RATE, in a plane perpendicular to the direction of propagation of wave. It is used to reduce depolarization effect on received WAVES.

The correct option is (b) False

The best explanation: In circular polarization at each point the ELECTRIC field of the ELECTROMAGNETIC wave has a constant magnitude but its direction changes as it rotates with time at a steady rate, in a plane perpendicular to the direction of PROPAGATION of the wave. It is used to REDUCE depolarization effect on received waves. It does not involve alignment between transmitting and receiving ANTENNA.

The correct answer is (b) False

Easy explanation: Color of any OBJECT is decided by the reflected color for opaque object and wavelength TRANSMITTED through it for TRANSPARENT object, while both reflector color and wavelength transmitted are considered for a translucent object.

The correct choice is (c) voltage for which amplitude, phase or frequency can be varied

For explanation I would say: Carrier wave is the wave with frequency HIGHER than the message signal, WHOSE certain CHARACTERISTICS like amplitude, phase or frequency are varied with respect to the instantaneous amplitude of the message signal. THUS forming the modulated wave which is the wave to be transmitted.

Correct option is (B) False

Explanation: The disadvantage of FM over AM is that in frequency modulation large bandwidth is REQUIRED. While, in CASE of advantages, FM is LESS prone to noise interference and has lower power consumption compared to AM.

Right choice is (b) LINEAR devices

Easy explanation: In low-LEVEL modulation, the generation of amplitude modulated signal takes place at low power levels. The generated AM signal is then amplified using a CHAIN of linear amplifiers, which are required to avoid WAVEFORM distortion. THUS, linear devices are used in low level amplitude modulated system.

Correct choice is (b) low level AM modulator

Best explanation: In low-level modulation, the GENERATION of amplitude modulated SIGNAL takes place at low power levels. The generated AM signal is then AMPLIFIED using a chain of LINEAR amplifiers, which are required to avoid waveform distortion. Thus, linear devices are used in low level amplitude modulated SYSTEM.

The CORRECT OPTION is (d) SHANNON-HARTLEY theorem

Explanation: According to Shannon Hartley theorem, a noiseless channel has INFINITE capacity.

The correct answer is (B) infinite CAPACITY

The explanation is: According to Shannon Hartley THEOREM, a noiseless channel has infinite capacity.

The correct answer is (b) False

The best I can explain: In high-level MODULATION, the generation of amplitude modulated SIGNAL TAKES place at high power levels. It has the advantage that linear amplifiers are not required.

The CORRECT option is (b) False

For explanation I would say: COLOR of any object is decided by the reflected color for opaque object and wavelength TRANSMITTED through it for transparent object, while both reflector color and wavelength transmitted are considered for a translucent object.

Right option is (b) False

For explanation I would say: Vestigial SIDEBAND Modulation (VSB) is a type of amplitude modulation in which the carrier and only one sideband is completely transmitted and the other sideband is partly transmitted. Thus, television production is DONE USING VSB modulation as it REDUCES bandwidth to HALF.

Correct OPTION is (b) False

For EXPLANATION I would SAY: In circular polarization at each point the electric field of the electromagnetic wave has a CONSTANT magnitude but its DIRECTION changes as it rotates with time at a steady rate, in a plane perpendicular to the direction of propagation of wave. It is used to reduce depolarization effect on received waves and not for discrimination between reception of beams.

Correct OPTION is (b) False

The best I can EXPLAIN: In duplex communication, two-way INTERACTION is FAVOURABLE simultaneously. Thus, a cordless telephone is duplex which USES separate frequencies for transmission in base and portable units.

Right choice is (a) PEAK clipper

Best EXPLANATION: Clipper is used to prevent the exceeding of OUTPUT from a PREDETERMINED FIXED value. It does not distorted the remaining part of the applied waveform.

The correct choice is (d) large bandwidth is required

The best I can explain: The DISADVANTAGE of FM over AM is that in frequency modulation large bandwidth is required. While, in CASE of advantages, FM is less prone to noise interference and has lower power CONSUMPTION compared to AM.

Right ANSWER is (c) is due to transverse nature of waves

Easy explanation: In electromagnetic waves, polarization is MAINLY due to the transverse nature of waves only. Transverse nature of electromagnetic waves mean that the ELECTRIC and magnetic fields are perpendicular to each other as well as perpendicular to the direction of propagation of waves.

Right CHOICE is (b) False

The explanation: Amplitude LIMITER circuit is used in FM receiver to remove the noise or any variation in amplitude present in the received signal. Thus, the output of the amplitude limiter has a CONSTANT amplitude. So it is only used in frequency MODULATION and not in amplitude modulation.

Correct option is (B) False

To explain I would say: Base modulation is preferred over collector modulation of a class C TRANSISTOR because low modulating power is required and collector saturation prevents complete modulation of a signal. Generally, Collector modulation has more advantages over Base modulation like high linearity, BETTER collector efficiency and such like.

Correct answer is (b) False

For explanation: Base modulation is preferred over collector modulation of a class C transistor because low modulating POWER is required and collector saturation prevents complete modulation of a signal. Generally, Collector modulation has more ADVANTAGES over Base modulation LIKE HIGH linearity, BETTER collector efficiency and such like.

The correct ANSWER is (B) 455 KHz

To explain I would say: In AM receivers, the standard intermediate frequency is approximately 455 KHz.

The correct CHOICE is (B) False

The explanation: Role of amplitude limiter in frequency modulation is to eliminate any change in amplitude of RECEIVED FM SIGNALS.

Correct OPTION is (b) False

To elaborate: Balanced modulator is used to produce 100% MODULATION by suppressing the carrier and passing only the two SIDEBANDS.

Right option is (a) prevent overmodulation

Easy EXPLANATION: CLIPPER is used to prevent the output of a CIRCUIT from exceeding a predetermined VOLTAGE. It does not distorted the remaining PART of the applied waveform.

Correct option is (b) False

The BEST I can EXPLAIN: BALANCED modulator is used to PRODUCE 100% modulation.