Technical Interview Questions For ECE

Q1. What is Electronics?

Ans: The study and use of electrical devices that operate by controlling the flow of electrons or other electrically charged particles.

Q2. What is meant by D-FF?

Ans: D-flip flop stands for Delay flip-flop, it delays input by one clock pulse

Q3. What are the functions of Base Station System (BSS)?

Ans: Functions of BSS are as follows:

• Radio path control.
• BTS and TC control.
• Connection establishment with MS-NSS.
• Mobility management, speech transcending.
• Connection of statistical data.

Q4. Define the terms.

Ans:

• Resistor: A resistor is an electrical component that limits or regulates the flow of electrical current in an electronic circuit.
• Capacitor : A capacitor is a passive electronic component that stores energy in the form of an electrostatic field.
• Diode: A diode is a semiconductor device with two terminals, typically allowing the flow of current in one direction only.
• Transistor: A transistor is a semiconductor device that regulates current or voltage flow and acts as a switch or gate for electronic signals.

Q5. What is the basic difference between Latches and Flip flops?

Ans: Latches are monostable and flip-flops are bistable

Q6. What is wireless communication concept ?

Ans:

Wireless communication is the transfer of information between two or more points that are not connected by any physical medium.Wireless communications can be via:

• Radio communication.
• Microwave communication.
• Light, Visible and Infrared communication.

Q7. What are the parts of Network Management System (NMS)?

Ans: Following are the parts of network management system:

• OMC: Operation and maintenance center – Computerized monitoring center.
• NMC: Network Management Center – Centralized control of a network is done here.
• OSS: Operation and support system – Used for supporting activities performed in an OMC and/or NMC.

Q8. What is a signal?

Ans: A signal is an electric current or electromagnetic field used to convey data from one place to another.

Q9. What is a multiplexer?

Ans: It is used to multiplex data from different sources normally used in TDM

Q10. What do you mean by frequency reuse ?

Ans: Each cellular Base Station is allocated a group of radio channels to be used. These radio channels can be used by another base station which is at a suitable distance away from it.

Q11. What are applications of DSP?

Ans: Some selected applications or digital signal processing that are often encountered in daily life are listed as follows:

• Telecommunication: Echo cancellation in telephone networks.
• Military Radar signal processing
• Consumer electronics Digital Audio/TV
• Instrumentation and control
• Image processing image representation, image compression
• Speech processing speech analysis methods are used in automatic speech recognition
• Medicine Medical diagnostic instrumentation such as computerized tomography (CT)
• Seismology DSP techniques are employed in geophysical exploration for oil and gas.
• Signal Filtering Removal of unwanted background noise.

Q12. What is sampling?

Ans: The process of obtaining a set of samples from a continuous function of time x(t) is referred to as sampling.

Q13. What is Race-around problem? How can you rectify it?

Ans: Race around condition occurs in a JK flip-flop when both the inputs are set to '1', it can be rectified using edge-triggered flip-flop or using master-slave flip-flops

Q14. What do you mean by Handoff ?

Ans: When a mobile moves into a different cell while a conversation is in progress, the Mobile Switching Center automatically transfers the call to a new channel belonging to the new Base Station.
Types of handoff:-
Hard Handoff
Soft Handoff

Q15. Explain radio environment in building.

• Building penetration: Building penetration depends on the material used for construction and architecture used. This varies building to building and is based on building construction.
• Building Height Effect: The signal strength is always higher at top floor and generally floor gain height is about 2.7dB/floor which is not dependent on building construction.
• Building Floor Reception: The signal isolation between floors in a multi floor building is on the average about 20dB. Within a floor of 150 * 150 feet, the propagation loss due to interior walls, depending on the wall materials is about 20 dB between the strong and the weak areas.

Q16. State sampling theorem.

Ans: It states that, while taking the samples of a continuous signal, it has to be taken care that the sampling rate is equal to or greater than twice the cut off frequencyand the minimum sampling rate is known as the Nyquist rate.

Q17. How can you convert an JK Flip-flop to a D Flip-flop?

Ans: Connect J to D and K to not(D)

Q18.What do you mean by Network and Switching Subsystem ?

Ans: It controls hand offs between cells in different BSSs, authenticates users , validates and maintains their accounts.It is mainly supported by four databases:-

1. Home Location Register.
2. Visitor Location Register.
3. Authentication Center.
4. Equipment Identity Register.

Q19. What are the various types of numbers for network identity?

Ans: Various types of number for network identity are as follows:

• MSISDN (Mobile station ISDN) Number: It is international mobile subscriber number which is normally called mobile number. It is unique worldwide.
• MSRN (Mobile Subscriber Routing Number) : MSRN is used during mobile terminate trunk call to provide location of mobile subscriber.

• HON (Hand Over Number) : HON is used for providing information required to transfer call from one B?SC to another BSC or to another MSC.
• ISMI (International Mobile Subscriber Identity Number) : Purpose of ISMI is for location update and authentication.
• TMSI (Temporary Mobile Subscriber Identity) : TMSI is used instead of IMSI to improve security efficiency of network.
• IMEI : International Mobile Equipment Identity.

Q20. What is cut-off frequency?

Ans: The frequency at which the response is -3dB with respect to the maximum response.

Q21. What do you mean by zener breakdown and avalanche breakdown?

Ans: zener breakdown takes place when very high voltage is applied to the diode this results in very high reverse current, as voltage is further increased minority carriers gain further momentum and strike atoms releases more carriers, which results in further increase in temp. It becomes vicious cycle and leads to avalanche breakdown or on other words "thermal runaway".

Q22. What are the different types of transmission impairment ?

Ans: When the received signal is not as same as the transmitted signal then it is known as Transmission impairment. Three different types of transmission impairment are:-

• Attenuation.
• Noise.
• Delay Distortion.

Q23. What are GPRS services?

Ans: GPRS services are defined to fall in one of the two categories:

• PTP (Point to point)
• PTM (Point to Multi point)

Some of the GPRS services are not likely to be provided by network operators during early deployment of GPRS due in part to the phased development of standard. Market demand is another factor affecting the decision of operators regarding which services to offer first.

Q24. What is pass band?

Ans: Passband is the range of frequencies or wavelengths that can pass through a filter without being attenuated

Q25. What are the different types of filters?

Ans: analog filters n digital filters not sure what u meant

Q26. Explain the steps involved in demodulating a signal.

Ans: Once the signal is coded, modulated and then sent, the receiver must demodulate the signal. This is usually done in two steps: Spectrum spreading (e.g., direct sequence or frequency hopping) modulation is removed.The remaining information bearing signal is demodulated by multiplying with a local reference identical in structure and synchronized with received signal.

Q27. What is the principle of microwave?

Ans: Microwave essentially means very short wave. The microwave frequency spectrum is usually taken to extend from 1GHZ to 30GHZ. The main reason why we have to go in for microwave frequency for communication is that lower frequency band are congested and demand for point to point communication continue to increase. The propagation of the microwave takes place in spacewave in v

Q28. What is impulse response?

Ans: Response given by a digital system when impulse signal is applied to it. Used to find out stability of system

Q29. How can a Pseudo Random Noise Code be usable?

Ans: To be usable for direct sequence spreading, a PN code must meet the following conditions:

• Sequence must be built from 2 leveled numbers.
• The codes must have sharp auto correlation peak to enable code synchronization.
• Codes must have a low cross-correlation value, the lower it is, more are the number of users which can be allowed in the system.
• The codes should be “balanced” i.e. the difference between ones and zeros in code may only be one.

Q30. What is the principle of microwave?

Ans: Microwave essentially means very short wave. The microwave frequency spectrum is usually taken to extend from 1GHZ to 30GHZ. The main reason why we have to go in for microwave frequency for communication is that lower frequency band are congested and demand for point to point communication continue to increase. The propagation of the microwave takes place in spacewave in view of high gain and directivity in the form of a bean and is similar to that of light.

Q31. What do you mean by half-duplex and full-duplex communication? Explain briefly.

Ans: Half-duplex: either sender or receiver can use the channel at one time eg walky-talky and full-duplex: sender or receiver or both can use the channel at one time eg telephone)