Analog Communication Interview Questions

Analog Communication Interview Questions

  • Anuj Awasthi
  • 03rd Jun, 2022

Analog Communication Interview Questions

1) What is Analog Communication?

Analog Communication is a data transmitting technique in a format that utilizes continuous signals to transmit data including voice, image, video, electrons, etc.

2) List basic components of a communication system?

Communication means sending, receiving, and processing of information between two or more devices. The basic components of a communication system are information source, input transducer, transmitter, communication channel, receiver, output transducer, and destination.

3) What are types of Signals?

Signals are classified into the following categories:

  • Continuous Time and Discrete Time Signals

  • Deterministic and Non-deterministic Signals

  • Even and Odd Signals

  • Periodic and Aperiodic Signals

  • Energy and Power Signals

  • Real and Imaginary Signals

4) What is an Analog Signal?

An analog signal is any continuous signal for which the time-varying feature (variable) of the signal is a representation of some other time-varying quantity, i.e., analogous to another time-varying signal.

5) What is Aperiodic Signal and periodic Signal?

Aperiodic signal: A signal which does not repeat itself after a specific interval of time is called Aperiodic signal.

Periodic signal: A signal that repeats its pattern over a period is called a periodic signal.

6) What is Modulation?

Modulation is the process of converting data into radio waves by adding information to an electronic or optical carrier signal. It is usually applied to electromagnetic signals: radio waves, lasers/optics, and computer networks.

7) Enlist some advantages of Modulation?

Some of the advantages of implementing modulation in communication systems are

  • Reduction of antenna size.
  • No signal mixing.
  • Increased communication range.
  • Multiplexing of signals.
  • Possibility of bandwidth adjustments.
  • Improved reception quality.

8) What are different types of Modulation?

There are 3 basic types of modulation:

  • Amplitude modulation: Amplitude modulation is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave.
  • Frequency modulation: Frequency modulation is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave.
  • Phase modulation: Phase modulation is a modulation pattern for conditioning communication signals for transmission. It encodes a message signal as variations in the instantaneous phase of a carrier wave. Phase modulation is one of the two principal forms of angle modulation, together with frequency modulation.

9) Please Explain Square Law Modulator?

Square law modulators are used for Amplitude Modulation. They have non-linear current-voltage characteristics. Square law modulators are highly nonlinear in low voltage region.

10) What are Demodulator?

A demodulator is an electronic circuit (or computer program in a software-defined radio) that is used to recover the information content from the modulated carrier wave.

11) What are Transmitters?

A transmitter is an electronic device used in telecommunications to produce radio waves in order to transmit or send data with the aid of an antenna. A transmitter is also known as a radio transmitter.

12) What are communications receiver?

A communications receiver is a type of radio receiver used as a component of a radio communication link. This is in contrast to a broadcast receiver which is used to receive radio broadcasts.

13) What is Sampling?

Sampling is considered a set of values used for functions that vary in specific time and space. In analog communication, the process of converting continuous-time signals into a sequence of discrete-time signals is known as Sampling. A certain set of data is continuously sampled in the sampling process.

14) What are the types of FM demodulation?

There are different types of FM demodulators are:

  • Slope Detector.
  • Foster-Seeley Discriminator.
  • Ratio Detector.
  • Pulse-Averaging Discriminators.
  • Quadrature Detectors.
  • Phase-Locked Loops.

15) What is multiplexing?

In telecommunications and computer networks, multiplexing is a method by which multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share a scarce resource. For example, in telecommunications, several telephone calls may be carried using one wire.

16) What is Superheterodyne receiver?

A superheterodyne receiver contains a combination of amplification with frequency mixing, and is by far the most popular architecture for a microwave receiver. To heterodyne means to mix two signals of different frequencies together, resulting in a "beat" frequency.

17) What Is Amplitude Modulation?

Amplitude modulation is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. In amplitude modulation, the amplitude of the carrier wave is varied in proportion to that of the message signal being transmitted.

18) What Is Pulse Position Modulation?

Pulse-position modulation is a form of signal modulation in which M message bits are encoded by transmitting a single pulse in one of the possible required time shifts. This is repeated every T seconds, such that the transmitted bit rate is bits per second.

19) Explain the principle of PPM?

Pulse Position Modulation (PPM) is an analog modulating scheme in which the amplitude and width of the pulses are kept constant, while the position of each pulse, with reference to the position of a reference pulse varies according to the instantaneous sampled value of the message signal.

20) What is PAM in practical circuits?

PAM (Pulse amplitude modulation) is defined as the data transmission by altering the amplitudes (power levels or voltage) of every pulse in a regular time sequence of electromagnetic pulses. The possible number of amplitudes can be infinite, but mostly it is some power of two so that the final output signal can be digital.

21) What is pass and stop band?

A passband is the range of frequencies or wavelengths that can pass through a filter. For example, a radio receiver contains a bandpass filter to select the frequency of the desired radio signal out of all the radio waves picked up by its antenna. The passband of a receiver is the range of frequencies it can receive.

A stopband is a band of frequencies, between specified limits, through which a circuit, such as a filter or a telephone circuit, does not allow signals to pass, or the attenuation is above the required stopband attenuation level.

22) What is a precision rectifier?

The precision rectifier, also known as a super diode, is a configuration obtained with an operational amplifier in order to have a circuit behave like an ideal diode and rectifier. It is very useful for high-precision signal processing.

23) What is DAC?

A DAC (Digital-to-Analog Converter) is a device that converts digital audio information (comprised of a series of 0s and 1s) into an analog audio signal that can be sent to a headphone amp. In most cases, you can not connect a headphone directly into a DAC.

24) What are RF and microwave filters?

Radio frequency (RF) and microwave filters represent a class of electronic filter, designed to operate on signals in the megahertz to gigahertz frequency ranges (medium frequency to extremely high frequency).

25) What are harmonics?

Harmonics are unwanted higher frequencies which superimposed on the fundamental waveform creating a distorted wave pattern. In an AC circuit, a resistance behaves in exactly the same way as it does in a DC circuit.

It is a signal or wave whose frequency is an integral (whole-number) multiple of the frequency of some reference signal or wave.

26) What is a multivibrator?

A multivibrator is an electronic circuit used to implement a variety of simple two-state devices such as relaxation oscillators, timers, and flip-flops. It consists of two amplifying devices (transistors, vacuum tubes or other devices) cross-coupled by resistors or capacitors. The first multivibrator circuit, the astable multivibrator oscillator, was invented by Henri Abraham and Eugene Bloch during World War I.

There are three types of multivibrator circuits Astable multivibrator, Monostable multivibrator, Bistable multivibrator.

27) What is an R-2R ladder network?

An R–2R ladder is a simple and inexpensive way to perform a digital-to-analog conversion, using repetitive arrangements of precise resistor networks in a ladder-like configuration.

These are the two main uses of R-2R ladder Network are DAC (Digital to Analogue Converter) and Multiple key Press Detector.

28) What is a Schmitt trigger?

Schmitt trigger is a comparator circuit with hysteresis implemented by applying positive feedback to the noninverting input of a comparator or differential amplifier. It is an active circuit that converts an analog input signal to a digital output signal.

29) What are active filters?

The filter is an electric network in any circuit theory, that used to change either phase or amplitude of signal characteristics with respect to its frequency. Ideally, this will not include any new frequency to the i/p nor it will alter the frequency component of that signal. An Active Filter utilizes an operational amplifier along with various electronic components like resistors, capacitors for filtering. Op-Amps are used to allow easily to make many types of active filters.

Butterworth, Chebyshev, Bessel, and Elliptical are types of Active filters.

30) What is a precision full wave rectifier?

A Precision full-wave rectifier is also known as an absolute value circuit. This means the circuit output is the absolute value of the input voltage regardless of polarity.

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