Question { TCS, 61107 }

how many flip flops you require for modulo 19 counter

Answer

for modulo -n counter we need logn (base 2) flipflops i.e
with n no. of flip flops we can have count from 0 to 2^(n-1)
so we need 5 flip flops to have mod-19 counter.

Question { Cadence, 34500 }

ring counter's initial state is 01000. after how many clock
cylces will it return to the initial state.

Answer

it is a 5 bit ring counter. its initial state is 01000.
for 1st clock the new state is 00100.
for the 2nd clock the new state is 00010.
like this after five clock signals i.e ticks it will reach
to its initial state.

Question { Videocon, 137695 }

Which type of modulation is used in TV transmission?

Answer

TV signal consists of audio and video signals. for audio FM
is used and for video AM is used. this is in india.
different countries follow different modulation techniques
for audio and video signals. in india we use PAL system.
thats why we use above said modulation techniques.

Question { ABB, 18467 }

what is the flip flop

Answer

its a sequential logic device in which we can store one bit
only. it is the basic building block of memory units.

Question { IBM, 14763 }

quantizer means

Answer

normally during conversion process of analog to digital we
use this quantization process. first of analog signal is
given to band limited filter to band limit the signal to a
particular frequency. then it is given to sampler to
convert that to discrete signal. the sampled signal is
continuous in amplitude and discrete in time. now this
signal is given to quantizer. which approximates all the
sampled values to the nearest quantized values. the no. of
quantized values are M=2^n where n is the no. of bits used
for coding. with n=3 the no. of quantized levels are 8.
with n=4 the no. of quantized levels are 16.with the
increase in no. of quantized levels we can decrease the
quantization noise but it increases required bandwidth.
after quantization the quantized signal is given to coder
to code the quantized signal. the output of the coder is
our required PCM.

finally quatizer approximates each sampled value of a
signal to the nearest quantized value.

Question { Cisco, 19545 }

which is better in short range commn AM or FM? and why

Answer

for short range of communication FM is better because noise
level is very low in fm rather than am. signal to noise
ratio is very high in fm when compared to am. the
modulation index is very high for fm so the signal to noise
ratio is [3/2(MI)^2] so fm is better for short range of
communication.

Question { Ericsson, 30815 }

highest voltage gain can be obtained from


a ).CC


b).CE


c).CB


d).Both CE and CB

Answer

high voltage gain is obtained from CB configuration only.
because the input impedance is low and out impedance is
high in CB configuration. so we get maximum voltage gain in
CB. whereas for CE the input impedance is moderate and
output impedance is moderate. so we get maximum power gain
from CE. and CC voltage gain is approximately one. so this
will give maximum current gain. CC is used for impedance
matching. CC is also known as emitter follower. because of
its unity gain.

cb will have max voltate gain.
ce will have max power gain.
cc will have max current gain.

Question { Ericsson, 30815 }

highest voltage gain can be obtained from


a ).CC


b).CE


c).CB


d).Both CE and CB

Answer

no doubt the maximum voltage gain will be obtained from CB
configuration only. for the answer 6: we dont connect any
resistors on either side of input and output. by its
connection we get input and output resistances. we know the
doping concentrations of emitter, base and collector.
depending upon the configuration we get input and output
impedences. nothing else.

Question { 7901 }

sun rises in the east,what is information content?

Answer

the information content in this is zero. because this is
sure event. the probability for having sure event is one.
so there is no information in this statement.

if the statement is " sun raises in the west" then the
inforamtion content is infinity.

I=10log(1/p) where p is the probability.

Question { Infosys, 3116 }

What is resistive diode?

Answer

A Defective Shorted diode is said to be Resistive diode.
This will show a very low or zero resistance in both forward
and reverse bias.

Question { 26136 }

what is difference between digital and discrete signals?

Answer

While differentiating signals we need to consider two
parameters: Amplitude and time.

For Discrete signals the amplitude is continuous but time
is discrete. Ex: PAM

Fof Digital signals the amplitude and time both are
discrete i.e., discontinuous. Ex: PCM

For Analog signals both amplitude and time are continuous.
Ex: Sine wave, AM etc.

Question { Accenture, 3305 }

can we tap digital signals?

Answer

Yes. Using Signal processing techniques we can tap digital
signals.