Interview Questions.

Top 100+ Electronics And Communications Engineering Interview Questions And Answers

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Top 100+ Electronics And Communications Engineering Interview Questions And Answers

Question 1. What Is Cut­off Frequency?

Answer :

The frequency at which the response is ­-3dB with recognize to the most reaction.

Question 2. What Is Op­-amp?

Answer :

An operational amplifier, regularly called an op­-amp , is a DCcoupled excessive ­gain electronic voltage amplifier with differential inputs and, normally, a single output. Typically the output of the op­amp is managed either by means of terrible remarks, which largely determines the value of its output voltage advantage, or by using high-quality comments, which enables regenerative gain and oscillation.

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Question three. What Is Transistor?

Answer :

In electronics, a transistor is a semiconductor tool generally used to increase or switch electronic signals. The transistor is the fundamental constructing block of computer systems, and all other modernelectronic gadgets. Some transistors are packaged individually however most are discovered in integrated circuits.

Question 4. What Is Diode?

Answer :

In electronics, a diode is a two­terminal device. Diodes have two lively electrodes between which the sign of interest may additionally float, and most are used for their unidirectional modern property.

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Question 5. What Is A Semi Conductor?

Answer :

A semiconductor is a solid cloth that has electrical conductivityin among that of a conductor and that of an insulator(AnInsulator is a material that resists the go with the flow of electrical modern-day. It is an object intended to guide or separate electric conductorswithout passing cutting-edge through itself)? it could vary over that extensive variety either completely or dynamically.

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Question 6. What Is Conductor?

Answer :

A substance, body, or device that quite simply conducts heat, electricity, sound, etc. Copper is a great conductor of  strength.

Question 7. What Is Inductor?

Answer :

An inductor is a passive electric tool hired in electrical circuits for its assets of inductance. An inductor can take many paperwork.

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Question eight. What Is Capacitor?

Answer :

A capacitor is an electrical/electronic tool that may store energyin the electric subject among a couple of conductors (known as “plates”). The process of storing strength inside the capacitor is called “charging”, and includes electric powered charges of same importance, but opposite polarity, constructing up on each plate. 
Capacitors are regularly used in electric and electronic circuits asenergy­garage devices. They also can be used to differentiate among high­frequency and occasional­frequency indicators. This assets makes them beneficial in electronic filters.

Capacitors are once in a while referred to as condensers. This time period is considered archaic in English, but maximum other languages use acognate of condenser to consult a capacitor.

Question 9. What Is Resistor?

Answer :

A resistor is a ­terminal electronic element that opposes anelectric cutting-edge via producing a voltage drop among its terminals in share to the cutting-edge, this is, in accordance with Ohm’s regulation: V= IR

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Question 10. What Is A Rectifier?

Answer :

A rectifier modifications alternating present day into direct modern. This manner is known as rectification. The three most important styles of rectifier are the half­wave, full­wave, and bridge. A rectifier is the other of an inverter, which changes direct modern-day into alternating contemporary. HWR­ The handiest type is the half­wave rectifier, which may be made with simply one diode. When the voltage of the alternating contemporary is positive, the diode will become forwardbiased and modern-day flows through it. When the voltage is terrible, the diode is reverse­biased and the cutting-edge stops.

The result is a clipped copy of the alternating cutting-edge waveform with most effective nice voltage, and an average voltage that is one 0.33 of the height input voltage. This pulsating direct present day is good enough for some additives, but others require a extra regular modern-day. This calls for a full­wave rectifier which could convert each elements of the cycle to wonderful voltage.

FWR­ The full­wave rectifier is basically  half­wave rectifiers, and can be made with  diodes and an earthed centre tap at the transformer. The high-quality voltage half of of the cycle flows via one diode, and the terrible half flows via the other. The centre faucet lets in the circuit to be completed due to the fact modern cannot float via the other diode. The end result remains a pulsating direct modern but with simply over half of the input peak voltage, and double the frequency.

Question eleven. What Is Crosstalk?

Answer :

Crosstalk is a shape of interference caused by signals in nearby conductors. The maximum commonplace instance is listening to an unwanted conversation on the cellphone. Crosstalk also can occur in radios, televisions, networking gadget, or even electric guitars.

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Question 12. What Is An Integrated Circuit?

Answer :

An included circuit (IC), additionally known as a microchip, is an electronic circuit etched onto a silicon chip. Their important blessings are low cost, low electricity, excessive performance, and really small length.

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Question 13. What Is A Transducer And Transponder?

Answer :

A transducer is a device, generally electric, digital, electro­mechanical, electromagnetic, photonic, or photovoltaic that converts one form of power or physical characteristic to another for diverse functions consisting of dimension or records transfer.

In telecommunication, the time period transponder (shortforTransmitter­responder and every so often abbreviated to XPDR, XPNDR, TPDR or TP) has the subsequent meanings:

An automatic device that gets, amplifies, andretransmits a signal on a exceptional frequency (see alsobroadcast translator).
An computerized tool that transmits a predetermined messagein reaction to a predefined acquired sign.
A receiver­transmitter in order to generate a respond signal upon right digital interrogation.
A communications satellite tv for pc’s channels are known as transponders, due to the fact every is a separate transceiver or repeater.
Question 14. What Is Oscillator?

Answer :

An oscillator is a circuit that creates a waveform output  from a right away modern enter. The two fundamental varieties of oscillator are harmonic and relaxation. The harmonic oscillators have easy curved waveforms, at the same time as relaxation oscillators have waveforms with sharp modifications.

Question 15. Example For Negative Feedback And Positive Feedback.

Answer :

Examples :

–ve feedback is —Amplifiers.
+ve feedback is – Oscillators.
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Question 16. Advantages Of Negative Feedback Over Positive Feedback.

Answer :

Much interest has been given with the aid of researchers to poor remarks methods, because bad remarks tactics lead structures toward equilibrium states. Positive comments reinforces a given tendency of a system and can lead a machine far from equilibrium states, in all likelihood inflicting pretty sudden outcomes.

Question 17. What Is A Feedback? And Explain Different Types Of Feedback.

Answer :

Feedback is a system wherein a few share of the output signal of a system is exceeded (fed again) to the input. This is regularly used to manipulate the dynamic behaviour of the system.

Types of feedback:

Negative feedback: This tends to reduce output (however in amplifiers, stabilizes and linearizes operation). Negative remarks feeds a part of a device’s output, inverted, into the gadget’s input? generally with the result that fluctuations are attenuated.

Positive remarks: This tends to increase output. Positive feedback, on occasion called “cumulative causation”, is a feedback loop system in which the system responds to perturbation (Aperturbation method a gadget, is an alteration of feature, triggered by way of external or inner mechanisms) inside the same path as the perturbation. In contrast, a system that responds to the perturbation within the contrary route is called a negative feedback gadget. 

Bipolar remarks: that may either growth or decrease output.

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Question 18. Explain Full Duplex And Half Duplex.

Answer :

Full duplex refers back to the transmission of records in  instructions simultaneously. For instance, a phone is a full­duplex devicebecause both parties can communicate straight away. In evaluation, a walkie­talkie is ahalf­duplex device due to the fact most effective one birthday celebration can transmit at a time. Most modems have a switch that lets you pick out among complete­duplex and half of­duplex modes. The preference depends on whichcommunications application you're strolling.

In complete­duplex mode, facts you transmit does no longer seem on yourscreen until it's been received and despatched back through the opposite birthday party. This allows you to validate that the records has been appropriately transmitted. If your show display shows  of each man or woman, it possibly means that your modem is about to 1/2­duplex mode whilst it should be in full­duplex mode.

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Question 19. What Is Barkhausen Criteria?

Answer :

Barkhausen standards, without which you may now not realize which situations, are to be satisfied for oscillations. 

“Oscillations will no longer be sustained if, at the oscillator frequency, the significance of the made from the switch gain of the amplifier and the importance of the comments thing of the feedback community ( the magnitude of the loop benefit ) are much less than solidarity”.

The circumstance of unity loop advantage ­Aβ = 1 is referred to as the Barkhausencriterion. This circumstance means that Aβphase of – Aβ is zero.

Question 20. What Is An Amplifier?

Answer :

An digital device or electric circuit this is used to enhance (expand) the power, voltage or modern-day of an implemented signal.

Question 21. Difference Between Cdma And Gsm.

Answer :

These are the 2 exclusive way of cell conversation being presently used worldwide. The simple difference lies inside the Multiplexing technique used within the aerial communication i.E. From Mobile Tower for your cellular and vice versa. CDMA makes use of Code Division Multiple Access as the call itself indicates, for instance you are in a hall occupied with number of human beings speakme one of a kind language.

You will discover that the only  language you realize might be heard by means of you and the others may be treated like noise. In the identical manner every CDMA cell communique takes area with a “code” communicating among them and the other stop if one is knowing that code then only it is able to concentrate to the facts being transmitted i.E. The conversation is inside the coded shape.

On the other hand GSM (Global System for Mobile Communications)makes use of narrowband TDMA, which permits 8 simultaneous calls on the equal radio frequency. TDMA works by using dividing a radio frequency into time slots after which allocating slots to a couple of calls. In this way, a single frequency can support multiple, simultaneous records channels.

Question 22. What Is Cdma, Tdma, Fdma?

Answer :

Code division a couple of access (CDMA) is a channel get right of entry to methodutilized by way of various radio communication technologies. CDMA employsspread­spectrum era and a special coding scheme (in which every transmitter is assigned a code) to allow more than one users to be multiplexed over the identical bodily channel. By assessment, time division a couple of get entry to (TDMA) divides get entry to by means of time, whilefrequency­division multiple get admission to (FDMA) divides it byfrequency.

An analogy to the hassle of a couple of get right of entry to is a room (channel) wherein humans desire to communicate with each other. To avoid confusion, people ought to take turns talking (time division), speak at special pitches (frequency department), or talk in distinctive instructions (spatial department). 

In CDMA, they would speak different languages. People speakme the identical language can understand every other, however no longer other people. Similarly, in radio CDMA, each institution of customers is given a shared code. Many codes occupy the same channel, however best customers related to a particular code can apprehend each other.

Question 23. What Is Multiplexing?

Answer :

Multiplexing (known as muxing) is a term used to refer to a processwhere a couple of analog message indicators or virtual information streams are combined into one sign over a shared medium. The aim is to share an costly useful resource. For example, in telecommunications, numerous telephone calls can be transferred the use of one wire.

Question 24. What Is Attenuation?

Answer :

Attenuation is the reduction in amplitude and depth of a sign. Signals may additionally attenuate exponentially by way of transmission through a medium, or by using increments calculated in digital circuitry or set by way of variable controls.
Attenuation is an vital belongings in telecommunications and ultrasound packages because of its importance in figuring out signal energy as a feature of distance. 
Attenuation is normally measured in gadgets of decibels per unit duration of medium (dB/cm, dB/km, and so forth) and is represented by using the attenuation coefficient of the medium in question.
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Question 25. What Is A Repeater?

Answer :

A repeater is an digital device that receives a signal and retransmits it at a higher degree and/or better power, or onto the other side of an obstruction, in order that the signal can cover longer distances without degradation.

Question 26. How Many Satellites Are Required To Cover The Earth?

Answer :

three satellites are required to cowl the whole earth, that's located at one hundred twenty diploma to every other. The existence span of the satellite is ready 15 years.

Question 27. What Is A Base Station?

Answer :

Base station is a radio receiver/transmitter that serves because the hub of the local wireless network, and might also be the gateway among a wired community and the wi-fi community

Basic C Interview Questions
Question 28. How Does A Mobile Work?

Answer :

When you talk into a cell phone it converts the sound of your voice to radiofrequency electricity (radio waves). The radio waves are transmitted through the air to a close-by base station. The base station then sends the decision through the telephone community till it reaches the character you're calling. When you receive a name in your cellular telephone the message travels thru the phone community until it reaches a base station near to you. The base station sends out radio waves, that are detected via your phone and converted lower back to speech. Depending on the gadget and the operator, the frequency that every operator utilises is 900MHz, 1800MHz or 2100MHz.

The mobile telephone network operates on the basis of a series of cells. Each mobile requires a radio base station to permit it to function.

There are three varieties of base station and each has a specific purpose:

The Macrocell is the largest type and gives the primary coverage for cellular telephone networks.
The Microcell is used to enhance potential in regions in which demand to make calls is excessive, which include buying centres.
The Picocell handiest has a variety of some hundred metres and can be used to reinforce susceptible signals within big homes.
Each base station can simplest address a positive quantity of calls at any person time. So if call for exceeds the capacity of a base station an additional base station is wanted.

Question 29. Where Do We Use Am And Fm?

Answer :

AM is used for video alerts as an example TV. Ranges from 535 to 1705 kHz. 
FM is used for audio alerts as an example Radio. Ranges from 88 to 108 MHz.
Question 30. Explain Am And Fm.

Answer :

AM­Amplitude modulation is a kind of modulation where the amplitude of the provider sign is varied in accordance with the records bearing signal. FM­Frequency modulation is a form of modulation where the frequency of the carrier sign is various according with the records bearing signal.

Question 31. Name The Modulation Techniques.

Answer :

For Analog modulation–AM, SSB, FM, PM and SM .
Digital modulation–OOK, FSK, ASK, Psk, QAM, MSK,CPM, PPM, TCM, OFDM.

Question 32. What Is Demodulation?

Answer :

Demodulation is the act of casting off the modulation from an analog signal to get the original baseband sign returned. Demodulating is important because the receiver machine gets a modulated sign with specific traits and it wishes to show it to base­band.

Question 33. What Is Modulation? And Where It Is Utilized?

Answer :

Modulation is the technique of varying a few function of a periodic wave with an external signals. Radio communique superimposes this statistics bearing sign onto a service signal. These excessive frequency provider signals can be transmitted over the air effortlessly and are able to visiting long distances. The characteristics (amplitude, frequency, or phase) of the service signal are various according with the information bearing signal. Modulation is utilized to ship an statistics bearing sign over lengthy distances.

Digital Communication Interview Questions
Question 34. Explain Rf?

Answer :

Radio frequency (RF) is a frequency or price of oscillation inside the variety of about 3 Hz to 300 GHz. This variety corresponds to frequency of alternating modern electric indicators used to provide and detect radio waves. Since maximum of this variety is past the vibration fee that most mechanical structures can reply to, RF usually refers to oscillations in electrical circuits or electromagnetic radiation.

Question 35. Difference Between Mobile And A Cell Phone.

Answer :

There isn't any difference, just language use, which differs from u . S . To us of a, so in Britain it's miles known as a mobile, and in USA and South Africa and different locations a cellular phone. Even in Europe the call differs. The Germans name it a “available”, which in English has absolutely another which means as an adjective, that means useful. In Italy it's far referred to as a telofonino or “little smartphone”.

 This distinction in British and American English is also obtrusive in many different matters we use each day, like lifts and elevators, nappies and diapers, pickups and vehicles. The listing is going on and on, any pupil of English has to determine which he or she can use, as the default putting.

Question 36. What Is Stop Band?

Answer :

A stopband is a band of frequencies, between special limits, in which a circuit, consisting of a filter or telephone circuit, does now not let indicators via, or the attenuation is above the specified stopband attenuation stage.

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Question 37. What Is Pass Band?

Answer :

Passband is the range of frequencies or wavelengths which can bypass through a filter without being attenuated.

Question 38. State Sampling Theorem.

Answer :

It states that, even as taking the samples of a continuous signal, it must be taken care that the sampling rate is same to or extra than twice the reduce off frequency and the minimum sampling charge is known as the Nyquist charge.

Question 39. What Is Sampling?

Answer :

The method of obtaining a set of samples from a non-stop characteristic of time x(t) is known as sampling.

Question forty. Difference Between Electronic And Electrical.

Answer :

Electronics work on DC and with a voltage range of ­48vDC to +48vDC. If the digital device is plugged into a widespread wall outlet, there can be a transformer internal if you want to convert the AC voltage you're presenting to the desired DC voltage wanted via the tool.

Examples: Computer, radio, T.V, and many others… 

Electric gadgets use line voltage (120vAC, 240vAC, and so forth…).Electric gadgets can also be designed to function on DC assets, however will be at DC voltages above 48v.

Examples: incandescent lights, heaters, fridge, range, and so on…

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