Pre-Emphasis & De-Emphasis Networks

-

Aim:- 

To draw the frequency response of Pre-emphasis & De-emphasis networks.

Introduction:-

Educational trainer a useful kit for the demonstration of Pre-emphasis & De-emphasis at different time constants & plot the graph of the frequency response of Pre-emphasis and De-emphasis networks. The kit consists of 200 Hz-20 kHz audio oscillator 70µ sec & 50µ sec De-emphasis networks.

 Pre-Emphasis Circuit Diagram:-



DE-Emphasis Circuit Diagram:-



Theory:-

Pre-emphasis refers to boosting the relative amplitudes of the modulating voltage for higher audio frequencies from 2 to approximately 15 kHz .De-emphasis means attenuating those frequencies by the amount by which they are boosted. However, Pre-emphasis is done at the transmitter and De-emphasis is done in the receiver. The purpose is to improve the signal-to-noise ratio for FM reception. A time constant of 75µ sec is specified in the RC or L/Z network for Pre-emphasis and De-emphasis.

Tabular column:-

Pre-Emphasis and De-Emphasis (Tabular column is the same for both)

Sl. Number

Frequency in Hz

i/p voltage Vin

volts

o/p voltage Vo in volts

Gain=Vo/Vin

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 








Procedure:-

1) Check the apparatus properly.

2) Connections are made as shown from the circuit diagram for Pe-emphasis.

3) Switch on the power supply.

4) Set the i/p voltage for frequency 1 kHz & o/p for 4 volts.

5) Take the i/p & o/p voltage simultaneously for varying audio range frequency i.e. (20 Hz- 20 kHz).

6) First, take for the Pre-emphasis.

7)  Then calculate again & plot a grad of frequency vs. gain of a pre-emphasis.

8) For De-emphasis repeat the steps up to 5 using de-emphasis trainer kit.

9) Then calculate the gain.

10) Plot the graph of frequency vs. gain.

Pre- Emphasis Nature of graph:-

De-Emphasis nature of  Graph:-


Result: -  

We have studied the Pre-emphasis & De-emphasis circuit & plotted the frequency response of Pre-emphasis & De-emphasis network.


 


 

Comments

Post a Comment

Its not necessary everyone should know everything feel free to ask or tell :)

Popular posts from this blog

Estimation of total chlorophyll by Aron's method

-
Purpose:- Estimation of total chlorophyll by Arnon's method. Requirement:- Spectrophotometer Buchner's funnel, filter paper test tube, Fresh leaves. measuring cylinder pestle & mortar 80% Acetone  Formula:- 20.2 (A645) +802 A663) / 1000 x W Principle:- Chlorophyll is extracted in 80% acetone & the absorption at 660 nm& 645 nm are read in s spectrophotometer using the absorption co-efficient, the amount of chlorophyll is calculated Procedure:- 1) Weigh 1 gm of finely cut & well mixed representative sample of a leaf or fruit tissue into a clean mortar 2) Grind the tissue to a fine pulp with the addition of 20mil of 80% acetone   3) Centrifuge (5000 rpm for 5 min) & transfer the supernatant to a 100 ml volumetric flask  4) Repeat this procedure until the residue is colorless wash the mortar and pestle  thoroughly with 80% acetone and collect the clear washing in the volumetric flask 5) Make up the volume to 100 ml with 80% acetone  6) ...
Read more

Here's what you need to know about sun's coronal heating

-
Image
The sun is a constant source of energy and light for the solar system, but it also holds many mysteries, one of which is the phenomenon of coronal heating. The corona is the outermost layer of the sun's atmosphere and it is much hotter than the surface of the sun itself. While the surface of the sun is around 5,500 degrees Celsius, the corona can reach temperatures of up to 2 million degrees Celsius. This unexplained heating of the corona is known as coronal heating. One theory for coronal heating is called "nanoflare" theory, which proposes that the corona is heated by small, frequent explosions, or nanoflares, that occur throughout the corona. These explosions are thought to be caused by magnetic reconnection, a process in which the sun's magnetic field lines break and then reconnect, releasing large amounts of energy. Another theory is known as "wave heating" which suggests that the corona is heated by waves, such as Alfvén waves, that travel ...
Read more

what would have happened if gravitation force was 9.9 km/s^2 instead of 9.8 km/s^2

-
Image
The force of gravity is one of the most fundamental and ubiquitous forces in the universe, governing the motion of everything from subatomic particles to entire galaxies. But what if the gravitational force was different from what we currently observe? Specifically, what would happen if the gravitational force was 9.9 km/s^2? To begin with, it's important to note that the current gravitational acceleration on the surface of the Earth is approximately 9.8 m/s^2, which means that an object dropped from a height of one meter will fall to the ground at a speed of 9.8 m/s. However, if the gravitational force was 9.9 km/s^2, this would be a thousand times stronger than it currently is. The most obvious consequence of such a strong gravitational force would be the weight of objects on Earth. At 9.9 km/s^2, the weight of an object would be much greater than it currently is, making it much harder for living organisms to move around. This would have a significant impact on the bi...
Read more