Answer / dinesh anand

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"

Answer / kamalakannan.l

Pre Emphasis

Pre emphasis is nothing but enhanging the message signal
and it is used for Transmission time.

De Emphasis

De Emphasis nothing but the comprese the message signal and
it is used for receiving time.

Answer / debopam banerjee

PRE-EMPHASIS :-

In an FM system the higher frequencies contribute more to
the noise than the lower frequencies. Because of this all FM
systems adopt a system of preemphasis where the higher
frequencies are increased in amplitude before being used to
modulate the carrier. The transfer function sketched above
is used for a preemphasis circuit for FM signals in the FM
band. The Time T = 75µs. For FM systems in the FM band m ~ 5
resulting in a S/N improvement of 19dB. With preemphasis
this can be increased by 4dB for a total of 23dB.





DE-EMPHASIS :-

At the receiver the higher frequencies must be deemphasised
in order to get back the origunal baseband signal. The
transfer function of the deemphasis circuit is shown above.

Answer / mandeep kaur maan

pre emphasis:
It is basically a technique used for FM transmission.
it means to enhance(increase the amplitude of) the higher
frequencies of the modulating signal so as to enhance the
signal to noise ratio ratio. this is done at the time of
transmission. th reason being that the noise affects the
higher frequencies more than the lower frequencies.

de-emphasis:
this is done at the time of recieving the FM signal
it means to lower the amplitude of the higher frequencies
(enhanced at the time of transmission) so that the noise
component that mixes at the transmission tme is cut off and
we recieve a better quality of the signal.

Answer / harimohan k. bhagwane

pre emphasis is a process which is used in transmitter side
to boosting the amplitude of higher modulating signal
before modulator.IF we used it after the modulator than
carrier &modulator signal will mixed and it is difficult to
verify which one is the modulating signal.

de emphasis is process which is used in receiver side
to reduced the signal & get their original signal.But it is
used after demodulator ckt.

Answer / u.p.pavan kumar yadav

pre emphasis:-boosting the higher frequencies before
transmission at the transmiter side is knowns as pre
emphasis

De emphasis:-Reducing the certain frequency in the recevier
side is known as de emphasis

Answer / disney_snoopy

Hi Debopam,

u said that
"The transfer function sketched above
is used for a preemphasis circuit for FM signals in the FM
band. The Time T = 75µs. For FM systems in the FM band m ~ 5
resulting in a S/N improvement of 19dB. With preemphasis
this can be increased by 4dB for a total of 23dB. "

But i cant see and graph here!!!

Answer / nidhant

pre- emphasis boosting of amplitude of higher
frequency signal.






de- reducing the amplitude of higher frequency componant

Answer / samyukthajakkam

preemphasis is the process of boosting the information signal in order to reduce the noise ocuurance .
eg:we can use high pass RC circuit,
Deemphasis is the process in which the boosted signal is brought down to normal information signal present at initial.
eg:we can use low pass RC circuit.

Answer / shravya

pre emphasis :Boosting of the high freuencies, in
accordance with a pre-arranged curve is pre emphasis.

de emphasis :The compensation at the receiver is de
emphasis

why hybrid parameter are called as h parameter?

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