Electronics and Communication Related Interview Questions - 3
41) What is conductor?
A substance, body, or device that readily conducts heat, electricity, sound, etc. Copper is a
good conductor of electricity.
42) What is a semi conductor?
A semiconductor is a solid material that has electrical conductivityin between that of
a conductor and that of an insulator(AnInsulator is a material that resists the flow of electric
current. It is an object intended to support or separate electrical conductorswithout passing
current through itself); it can vary over that wide range either permanently or dynamically.
43) What is diode?
In electronics, a diode is a two-terminal device. Diodes have two active electrodes between
which the signal of interest may flow, and most are used for their unidirectional current
property.
44) What is transistor?
In electronics, a transistor is a semiconductor device commonly used to amplify or
switch electronic signals. The transistor is the fundamental building block of computers, and
all other modernelectronic devices. Some transistors are packaged individually but most are
found in integrated circuits.
45) What is op-amp?
An operational amplifier, often called an op-amp , is a DC-coupledhigh-gain electronic
voltage amplifier with differential inputs[1] and, usually, a single output. Typically the output
of the op-amp is controlled either by negative feedback, which largely determines the
magnitude of its output voltage gain, or by positive feedback, which facilitates regenerative
gain and oscillation.
46) what is the differnce between SCR and diode rectifier?
diode is a 2 terminal device, in scr gate controls the rectifing.
SCR is used in High frequency applications but diode is low freuency devices, SCR can be in high temparatures but not diode.
47) whatis intersymbol interference
In telecommunication, intersymbol interference (ISI) means a form of distortion of a signal that causes the previously transmitted symbols to have an effect on the currently received symbol.
This is usually an unwanted phenomenon as the previous symbols have similar effect as noise, thus making the communication less reliable.
ISI is usually caused by echoes or non-linear frequency response of the channel. Ways to fight against intersymbol interference include adaptive equalization or error correcting codes (especially soft decoding with Viterbi algorithm).
48) 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
49) 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.
50) What do you mean by ASCII, EBCDIC?
ASCII (American Standard Code for Information Interchange), is a character encoding
based on the English alphabet.
EBCDIC (Extended Binary Coded Decimal Interchange Code) is an 8-bit character encoding
used on IBM mainframe operating systems
51) 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.
52) What is meant by pre-emphasis and de-emphasis?
Pre-emphasis
" Improving the signal to noise ratio by increasing the magnitude of higher frequency signals with respect to lower frequency signals"
De-emphasis
" Improving the signal to noise ratio by decreasing the magnitude of higher frequency signals
with respect to lower frequency signals"
53) What is Race-around problem? How can you rectify it?
A condition in logic network in which the difference in propagation times through two or
more signal paths in the network can produce an erroneous output.in jk flip flop race around
problem will occur when both the inputs are high. it can be prevented by using master slave
jk flip flop
54) What is the basic difference between Latches and Flip flops?
latch works without clock signal,but works with a control signal and it is level triggered
device.whereas flip flop is a 1 bit storage element and works with a clock signal.its a edge
triggered device. normally latches are avoided and flip flops are preferred.
55) what is Barkhausen Criterion?
1./AB/=1,i.e. the magnitude of loop gain must be unity
2.the total prase shift around the closed loop is zero or 360 degrees.
56) what are active and Passive Components?
ACTIVE COMPONENTS The components which produce the energy in the form of
current or voltage are called as active components.
Example:transistors etc,.
57) What is difference between Microprocessor and Microcontroller ?
Microprocessors generally require external components to implement program memory, ram memory and Input/output.
Intel's 8086, 8088, and 80386 are examples of microprocessors.
Micro controllers incorporate program memory, ram memory and
input/output resources internal to the chip.
Microchip's pic series and Atmel's AVR series are examples of micro controllers.
58) Why is Zener Diode always used in Reverse Bias condition ?
When biased in the forward direction it behaves just like a normal signal diode passing the
rated current, but when a reverse voltage is applied to it the reverse saturation current remains
fairly constant over a wide range of voltages.
The reverse voltage increases until the diodes breakdown voltage VB is reached at which point a process called Avalanche Breakdown occurs in the depletion layer and the current flowing through the zener diode
increases dramatically to the maximum circuit value (which is usually limited by a series
resistor).
This breakdown voltage point is called the "zener voltage" for zener diodes.
59) Define Analog and Digital Signal Processing
Analog signal processing
Analog signal processing is for signals that have not been digitized, as in classical radio,
telephone, radar, and television systems. This involves linear electronic circuits such
as passive filters, active filters, additive mixers, integrators and delay lines. It also involves
non-linear circuits such as compandors, multiplicators (frequency mixers and voltage
controlled amplifiers), voltage-controlled filters,voltage-controlled oscillators and phaselocked
loops.
Discrete time signal processing
Discrete time signal processing is for sampled signals that are considered as defined only at
discrete points in time, and as such are quantized in time, but not in magnitude.
Analog discrete-time signal processing is a technology based on electronic devices such
as sample and hold circuits, analog time-division multiplexers, analog delay lines and analog
feedback shift registers. This technology was a predecessor of digital signal processing (see
below), and is still used in advanced processing of gigahertz signals.
The concept of discrete-time signal processing also refers to a theoretical discipline that
establishes a mathematical basis for digital signal processing, without taking quantization
error into consideration.
60) What is RS in RS-232 ?
RS-232 (Recommended Standard - 232) is a telecommunications standard for binary serial
communications between devices.
It supplies the roadmap for the way devices speak to each other using serial ports.
The devices are commonly referred to as a DTE (data terminal equipment) and DCE (data communications equipment);
for example,
a computer and modem, respectively
A substance, body, or device that readily conducts heat, electricity, sound, etc. Copper is a
good conductor of electricity.
42) What is a semi conductor?
A semiconductor is a solid material that has electrical conductivityin between that of
a conductor and that of an insulator(AnInsulator is a material that resists the flow of electric
current. It is an object intended to support or separate electrical conductorswithout passing
current through itself); it can vary over that wide range either permanently or dynamically.
43) What is diode?
In electronics, a diode is a two-terminal device. Diodes have two active electrodes between
which the signal of interest may flow, and most are used for their unidirectional current
property.
44) What is transistor?
In electronics, a transistor is a semiconductor device commonly used to amplify or
switch electronic signals. The transistor is the fundamental building block of computers, and
all other modernelectronic devices. Some transistors are packaged individually but most are
found in integrated circuits.
45) What is op-amp?
An operational amplifier, often called an op-amp , is a DC-coupledhigh-gain electronic
voltage amplifier with differential inputs[1] and, usually, a single output. Typically the output
of the op-amp is controlled either by negative feedback, which largely determines the
magnitude of its output voltage gain, or by positive feedback, which facilitates regenerative
gain and oscillation.
46) what is the differnce between SCR and diode rectifier?
diode is a 2 terminal device, in scr gate controls the rectifing.
SCR is used in High frequency applications but diode is low freuency devices, SCR can be in high temparatures but not diode.
47) whatis intersymbol interference
In telecommunication, intersymbol interference (ISI) means a form of distortion of a signal that causes the previously transmitted symbols to have an effect on the currently received symbol.
This is usually an unwanted phenomenon as the previous symbols have similar effect as noise, thus making the communication less reliable.
ISI is usually caused by echoes or non-linear frequency response of the channel. Ways to fight against intersymbol interference include adaptive equalization or error correcting codes (especially soft decoding with Viterbi algorithm).
48) 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
49) 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.
50) What do you mean by ASCII, EBCDIC?
ASCII (American Standard Code for Information Interchange), is a character encoding
based on the English alphabet.
EBCDIC (Extended Binary Coded Decimal Interchange Code) is an 8-bit character encoding
used on IBM mainframe operating systems
51) 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.
52) What is meant by pre-emphasis and de-emphasis?
Pre-emphasis
" Improving the signal to noise ratio by increasing the magnitude of higher frequency signals with respect to lower frequency signals"
De-emphasis
" Improving the signal to noise ratio by decreasing the magnitude of higher frequency signals
with respect to lower frequency signals"
53) What is Race-around problem? How can you rectify it?
A condition in logic network in which the difference in propagation times through two or
more signal paths in the network can produce an erroneous output.in jk flip flop race around
problem will occur when both the inputs are high. it can be prevented by using master slave
jk flip flop
54) What is the basic difference between Latches and Flip flops?
latch works without clock signal,but works with a control signal and it is level triggered
device.whereas flip flop is a 1 bit storage element and works with a clock signal.its a edge
triggered device. normally latches are avoided and flip flops are preferred.
55) what is Barkhausen Criterion?
1./AB/=1,i.e. the magnitude of loop gain must be unity
2.the total prase shift around the closed loop is zero or 360 degrees.
56) what are active and Passive Components?
ACTIVE COMPONENTS The components which produce the energy in the form of
current or voltage are called as active components.
Example:transistors etc,.
57) What is difference between Microprocessor and Microcontroller ?
Microprocessors generally require external components to implement program memory, ram memory and Input/output.
Intel's 8086, 8088, and 80386 are examples of microprocessors.
Micro controllers incorporate program memory, ram memory and
input/output resources internal to the chip.
Microchip's pic series and Atmel's AVR series are examples of micro controllers.
58) Why is Zener Diode always used in Reverse Bias condition ?
When biased in the forward direction it behaves just like a normal signal diode passing the
rated current, but when a reverse voltage is applied to it the reverse saturation current remains
fairly constant over a wide range of voltages.
The reverse voltage increases until the diodes breakdown voltage VB is reached at which point a process called Avalanche Breakdown occurs in the depletion layer and the current flowing through the zener diode
increases dramatically to the maximum circuit value (which is usually limited by a series
resistor).
This breakdown voltage point is called the "zener voltage" for zener diodes.
59) Define Analog and Digital Signal Processing
Analog signal processing
Analog signal processing is for signals that have not been digitized, as in classical radio,
telephone, radar, and television systems. This involves linear electronic circuits such
as passive filters, active filters, additive mixers, integrators and delay lines. It also involves
non-linear circuits such as compandors, multiplicators (frequency mixers and voltage
controlled amplifiers), voltage-controlled filters,voltage-controlled oscillators and phaselocked
loops.
Discrete time signal processing
Discrete time signal processing is for sampled signals that are considered as defined only at
discrete points in time, and as such are quantized in time, but not in magnitude.
Analog discrete-time signal processing is a technology based on electronic devices such
as sample and hold circuits, analog time-division multiplexers, analog delay lines and analog
feedback shift registers. This technology was a predecessor of digital signal processing (see
below), and is still used in advanced processing of gigahertz signals.
The concept of discrete-time signal processing also refers to a theoretical discipline that
establishes a mathematical basis for digital signal processing, without taking quantization
error into consideration.
60) What is RS in RS-232 ?
RS-232 (Recommended Standard - 232) is a telecommunications standard for binary serial
communications between devices.
It supplies the roadmap for the way devices speak to each other using serial ports.
The devices are commonly referred to as a DTE (data terminal equipment) and DCE (data communications equipment);
for example,
a computer and modem, respectively
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