Electronics - Interview Qts-6

Interview Questions- MBA Admissions- Job Interviews

              - Electronics and Communication, Applied Electronics

• Distinguish between Angle modulation and Amplitude modulation.


In amplitude Modulation as the amplitude of given signal varies, the amplitude of carrier signal also varies in the same way.In angle modulation, the frequency or phase may vary according to the amplitude of given signal"

• What is Biasing?

Biasing is a process of connecting dc voltage to a device by which we can select the operating point of the device. by biasing actually we select the operating point of the device.

• What do you mean by 3 dB cutoff frequency? Why is it 3 dB, not 1 dB?

3db implies 70%(o.7o7) of the power,i'e we r interested to consider the bandwidth range from peak to 70% b'coz uptp 70% its reliable.hence 3db is called as half power freq. 3db value is the mean square value which is 70% of the maximum value.

• What is meant by pre-emphasis


Pre-emphasis -Improving the signal to noise ratio by increasing the magnitude of higher frequency signals with respect to lower frequency signal"

• What is meant by de-emphasis?

De-emphasis-Improving the signal to noise ratio by decreasing the magnitude of higher frequency signals with respect to lower frequency signals"

• What is sampling theorem?

It is defined as the sampling frequency should be greater than or equal to twice the sampling frequency then we can generate the original signal if the condition does not satisfy we get the signal in the distorted mannerit is given as ( fs >/ 2 fs)

• Explian FIR filters


Finite impulse response (FIR) filter is a type of a digital filter. The impulse response, the filter's response to a Kronecker delta input, is 'finite' because it settles to zero in a finite number of sample intervals. This is in contrast to infinite impulse response filters which have internal feedback and may continue to respond indefinitely.

• Quote few examples of FIR Filters

A FIR filter has a number of useful properties which sometimes make it preferable to an infinite impulse response filter. FIR filters: Are inherently stable. This is due to the fact that all the poles are located at the origin and thus are located within the unit circle. Require no feedback. This means that any rounding errors are not compounded by summed iterations. The same relative error occurs in each calculation. They can be designed to be linear phase, which means the phase change is proportional to the frequency.

• What are IIR filters

Infinite impulse response (IIR) is a property of signal processing systems. They have an impulse response function which is non-zero over an infinite length of time. The simplest analog IIR filter is an RC filter made up of a single resistor (R) feeding into a node shared with a single capacitor (C). This filter has an exponential impulse response characterized by an RC time constant.

• what are Asynchronous transmission


Asynchronous transmission uses start and stop bits to signify the beginning bit ASCII character would actually be transmitted using 10 bits e.g.: A "0100 0001" would become "1 0100 0001 0". The extra one (or zero depending on parity bit) at the start and end of the transmission tells the receiver first that a character is coming and secondly that the character has ended. This method of transmission is used when data is sent intermittently as opposed to in a solid stream. In the previous example the start and stop bits are in bold. The start and stop bits must be of opposite polarity. This allows the receiver to recognize when the second packet of information is being sent.

• what are Synchronous transmission

Synchronous transmission uses no start and stop bits but instead synchronizes transmission speeds at both the receiving and sending end of the transmission using clock signals built into each component. A continual stream of data is then sent between the two nodes. Due to there being no start and stop bits the data transfer rate is quicker although more errors will occur, as the clocks will eventually get out of sync, and the receiving device would have the wrong time that had been agreed in protocol (computing) for sending/receiving data, so some bytes could become corrupted (by losing bits). Ways to get around this problem include re-synchronization of the clocks and use of check digits to ensure the byte is correctly interpreted and received.

Electronics - Interview Qts-3

Interview Questions- MBA Admissions- Job Interviews

                   - Electronics and Communication, Applied Electronics

• What is Yagi-Uda antenna ?


A Yagi-Uda antenna is familiar as the commonest kind of terrestrial TV antenna to be found on the rooftops of houses. It is usually used at frequencies between about 30MHz and 3GHz, or a wavelength range of 10 metres to 10 cm

• What is difference between Piconet and Scatternet ?

"A piconet is the type of connection that is formed between two or more Bluetooth-enabled devices, one device takes the role of 'master', and all other devices assume a 'slave' role for synchronization reasons. Where as a scatternet is a number of interconnected piconets that supports communication between more than 8 devices. Scatternets can be formed when a member of one piconet (either the master or one of the slaves) elects to participate as a slave in a second, separate piconet."

• What is MIMO ?

MIMO- multiple-input and multiple-output, , is the use of multiple antennas at both the transmitter and receiver to improve communication performance. It is one of several forms of smart antenna technology.

• What is VOIP ?

Voice over Internet Protocol (Voice over IP, VoIP) is one of a family of internet technologies, communication protocols, and transmission technologies for delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet.

• What is EDFA ?

Erbium-doped fiber amplifier. EDFA is an optical repeater device that is used to boost the intensity of optical signals being carried through a fiber optic communications system.

• what do you understand by microwaves? why these are called micro

Micro waves are those waves whose wavelength is less than 30 cms or freq ranging from 1 GHz to 1000 GHz.

• How do microwave oven works??

The main component of microwave oven is magnatron which generates frequency of appox. 2.4 GHz.

• What do you mean by 3 dB cutoff frequency? Why is it 3 dB, not 1 dB?

3dB is the half power value

• What is 2G?


2G is short for second generation wireless telephone technology.It is actually an upgradation of 1G which was analog in nature..but 2G is digital in nature..moreover its penetration in mobile networks is much higher.

• What is 3G?

3G is short for 3rd generation wireless telephone technology. It is a further upgradation of 2G..its data rates are higher and it is supposed to be ranged upto 14 mbps. NTT Docomo of Japan used it first. (After this u may expect questions from Docomo,so i u r aware use this statement)

Many new applications like Mobile TV,Internet Browsing, Video Conf,Tele-Medicine can be used.

• what is 4G?

4th Generation technology. Have very high data rates upto 100Mbps. and can be used for Online Gaming, HDTV viewing,etc..

• Why are video signals amplitude modulated and sound signal frequency modulated in composite video signal.?

Both picture and sound signals from different stations are concentrated within the same range of frequencies. Therefore, radiation from different stations would be hopelessly and inextricably mixed up and it would be impossible to separate one from the other at the receiving end. Thus

in order to be able to separate the intelligence from different stations, it is necessary to translate them all to different portions of the electromagnetic spectrum depending on the carrier frequency assigned to each station. Also the sound signal is frequency modulated because of its inherent merits of interference-free reception.