Answer / mohamed hussein

de-emphasis is the complement of pre-emphasis, in the
antinoise system called emphasis. Emphasis is a system
process designed to decrease, (within a band of
frequencies), the magnitude of some (usually higher)
frequencies with respect to the magnitude of other (usually
lower) frequencies in order to improve the overall signal-
to-noise ratio by minimizing the adverse effects of such
phenomena as attenuation differences or saturation of
recording media in subsequent parts of the system.
Special time constants dictate the frequency response
curve, from which one can calculate the cutoff frequency

Answer / vibhor

we know that noise effect is more in higher frequencies than lower frequency......but we transmit the higher frequency signal for large distance communication so we can solve this problem by pre emphasis and de emphasis technique.

pre emphasis
this technique is used at the transmitting time before the modulator.In it the amplitude of higher frequency is increased so that the signal to noise ratio is incresed...

de emphasis
this tech is used at the reciver side after the demodulation to collect the original signal.In it the amplitude of higher frequency is decreased so that we collect the original signal.

Answer / satheeshkumar.s, somanur

PRE-EMPHASIS:
In FM system,Emphasis is a system process designed to
decrease the magnitude of higher frequencies to the
magnitude of lower frequencies in order to improve the SNR
ratio.So, Pre-emphasis is just a process where the magnitude
of the higher frequencies are increased before being used to
modulate the carrier signal.

DE-EMPHASIS:
The process which takes place at the receiver where
the magnitude of the higher frequencies are emphasis-ed to
get back the original signal.

Answer / akash

Devopam Bannerjee (Ans #3) just copied his answer verbatim
from this link.

http://cnyack.homestead.com/files/modulation/pre_emp.htm

You might want to check it out to see if you get the
picture. !! ;-)

Answer / shruti

Pre-emphasis is a strong high frequency boost before the transmitter, and an equally strong high frequency attenuation in every radio.

In telecommunication, de-emphasis is the complement of pre-emphasis, in the antinoise system called emphasis. Emphasis is a system process designed to decrease, (within a band of frequencies), the magnitude of some (usually higher) frequencies with respect to the magnitude of other (usually lower) frequencies in order to improve the overall signal-to-noise ratio by minimizing the adverse effects of such phenomena as attenuation differences or saturation of recording media in subsequent parts of the system.

Answer / p.siva prasad

pre emphasis: pre emaphasis nothing but to increasing the
amplitude of the message signal


de emphasis: it is nothing but to reduce the amplitude of
the message signal

to use the pre & de emphasis in the circut to get un
distorsion wave form at out put side

Answer / nandhikaa.c

pre-emphasis:
this is the process with which the message signal is enhanced that its amplitude is increased in order to let it to transmit over longer distanceand to increase its signal to noise ratio.
de-emphasis:
this de-emphasis is thus the mirror image of the pre-emphasis process.

Answer / priyanka sharma

pre
emphasis:

we artificially boast the high frequency components of the signal in accordance with a predetermined curve at the transmitter.This is called pre-emphasis.

de
emphasis:

at the receiver end these components are attenuated after demodulation in accordance with predetermined curve .This is called de-emphasis.

Answer / kanth

Pre emphasis is the process of transferring information from transmitter to free space by adding required carrier signal . & de emphasis is the process of receiving information from free space to receiver by subtracting the useless information.

Answer / shashi kant bharti

pre emphasis

the technique which is used to increases the signal power at higher audio frequency is called pre emphasis " the circuit boosts the signal amplitude at higher frequency in the massage band

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