Analog Communications Questions and Answers – Multitone Wideband FM

This set of Analog Communications Multiple Choice Questions & Answers (MCQs) focuses on “Multitone Wideband FM”.

1. What will be the effect if we loading down a tuned-circuit amplifier?
a) it will raise the Q factor of tuned circuit
b) it will lower the Q factor of tuned circuit
c) it will multiply the Q factor by a constant
d) it will have no effect on Q factor

Explanation: Loading down a tuned circuit will automatically lower the Q factor of any circuit. Q factor characterizes resonator’s bandwidth relative to its center frequency. It is a measure of the performance of the resonant circuit.

2. What is the baseband bandwidth for a voice grade signal?
a) atleast 10KHz
b) atleast 5KHz
c) approximately 3KHz
d) approximately 15KHz

Explanation: The fixed standard baseband bandwidth for a voice grade signal is approximately close to 3KHz.

3. Miller effect can reduce the bandwidth of an amplifier.
a) True
b) False

Explanation: Miller effect is responsible for limiting the gain of an amplifier at higher frequencies due to Miller capacitance between the output and input. Also, oscillations in the amplifier occur due to input/output feedback.

4. What will be the reason of miller effect in BJT?
b) collector-to-emitter capacitance
c) base-to-emitter capacitance
d) base-to-collector capacitance

Explanation: Miller effect is responsible for the increase in equivalent input capacitance of an inverting voltage amplifier. The increase equivalent input capacitance is given by, CM = C(1 + AV). In BJT, miller effect is due to base-to-collector capacitance.

5. Trimmers and padders are ________
a) two types of adjusting tools

Explanation: Trimmers and padders are the two types of small adjustable capacitors. Its capacitance can be adjusted to the required value.

6. What is the full form of IF?
a) Intermediate Frequency
b) Internal Frequency
c) Indeterminate Frequency
d) Image Frequency

Explanation: IF stands for intermediate frequency. It is a frequency to which a carrier wave is shifted, with the help of a mixer, as an intermediate step in transmission and reception. This IF is more suitable for executing further processes.

7. What is the full form of AGC?
a) Automatic Gain Control
b) Audio Gain Control
c) Automatic Gain Conversion
d) Active Gain Control

Explanation: AGC stands for Automatic Gain Control. It is closed loop feedback regulating circuit. Its purpose is to provide a controlled signal amplitude at its output, irrespective of changes in it’s input signal amplitude.

8. Sensitivity measures ________

Explanation: Sensitivity and Selectivity are two key components of any circuit. Sensitivity is used to measure the weakest signal that is received at the receiver.

9. Selectivity measures ________
a) the range of frequencies that receiver can select
b) with two signals close in frequency, the ability to select one and reject other
c) how well adjacent frequencies are separated by the demodulator
d) how well adjacent frequencies are separated in the mixer

Explanation: Sensitivity and Selectivity are two key components of any circuit. Selectivity is used to measure the range of frequencies that the receiver can select. Sensitivity is the ability of the receiver to amplify weak signals.

Sanfoundry Global Education & Learning Series – Analog Communications.

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