30 Jun 2018

Slope Overload Distortion and Granular (Idle Noise), Quantization Noise in Delta Modulation

Slope Overload Distortion and Granular (Idle Noise)

Slope overload distortion and granular (idle noise) are the two major drawbacks of delta modulation.
So here we are going to discuss both of these drawbacks of delta modulation-
Watch the Complete Video Here-

Slope Overload Distortion

This distortion is caused due to large dynamic range of the input signal. Because When the input signal rising rate is very high, then the staircase signal cannot approximate it correctly.
So it creates large error between the original input signal X(t) and the staircase approximated signal. This noise (error) is known as slope overload distortion.

Solution of Slope Overload Distortion

The step size must be increased, when the input signal has high Slope. Therefore we use Adaptive Delta Modulation technique where the step size is increased when large dynamic variations are present in the signal X(t), to reduce the quantization errors present in delta modulation. 

Granular Noise (Idle Noise)

This noise (error) occurs when the step size is too large in comparison to small variations in the input signal.
So because of large step size in comparison to the signal having very small variations or constant; error is introduced between the input signal and the approximated staircases signal. This error is known as the granular or idle noise.

Solution of the Granular Noise (Idle Noise)

We can overcome the problem of granular noise by keeping the step size small.

We use this in adaptive delta modulation technique, where the step size is reduced as per the small signal value to reduce the difference between the signal and its approximation (staircase waveform).

Now observe the image shown below-
This image shows the quantisation errors in Delta modulation (slope overload distortion and granular noise).


Slope Overload Distortion, Granular Noise, Drawbacks of Delta Modulation, Quantization errors in delta modulations, limitations of delta modulation
Slope Overload Distortion and Granular Noise in Delta Modulation

As you can see in the image that the shaded part in red color shows the slope overload distortion present in Delta modulation while the shaded region in green color represents the granular noise which is also known as idle noise. Both of these errors (noises) are quantization errors and are present in Delta modulation.

28 Jun 2018

Frequency Translation/Frequency Mixing/Frequency Conversion/Heterodyning (Basic Concepts and Need)

In this post we will discuss, what is Frequency Translation. This is also known by other names like- Frequency Mixing, Frequency Conversion or Heterodyning.


What is Frequency Mixing (Frequency Conversion/ Heterodyning/Frequency Translation) and Why it is NEEDED?

It is generally required to translate or shift the modulated signal to a new band of frequency in the processing of signals in the communication systems.
Because the received signal translated to a fixed intermediate frequency (IF), can easily be Amplified, Filtered and Demodulated (Detected).

For example- in most commercial AM radio receivers, the received radio frequency (RF) signal is 560- 1640 kHz. But this is shifted to an Intermediate Frequency (IF) which is 455 kHz band, for the purpose of processing.
This is done because the received signal, that has been translated to a fixed intermediate frequency, easily be Amplified, Filtered and Demodulated.

The device which is used to perform this operation of frequency translation of the modulated wave is known as the "Frequency Mixer" and this process is also called as frequency conversion, frequency mixing or heterodyning.

Read More-

Go To HOME Page
   
FREQUENCY SPECTRUM OF AMPLITUDE MODULATION (WAVEFORMS AND EQUATIONS DERIVATION)

AMPLITUDE MODULATION (TIME DOMAIN EQUATIONS AND WAVEFORMS)

ADVANTAGES AND DISADVANTAGES OF DIGITAL COMMUNICATION SYSTEM

ADVANTAGES OF OPTICAL FIBER COMMUNICATION

STEP INDEX OPTICAL FIBER (MULTIMODE AND SINGLE MODE STEP INDEX FIBERS)

PULSE MODULATION TECHNIQUES (PAM, PWM, PPM, PCM)

OPTICAL FIBER: STRUCTURE AND WORKING PRINCIPLE

PULSE AMPLITUDE MODULATION (PAM)

COMPARISON OF PAM, PWM, PPM MODULATION TECHNIQUES

PULSE WIDTH MODULATION (PWM)

CONTINUOUS TIME AND DISCRETE TIME SIGNALS (C.T. AND D.T. SIGNALS)

NEED AND BENEFITS OF MODULATION

PULSE POSITION MODULATION (PPM)

OPTICAL FIBERS IN COMMUNICATION: COVERS ALL IMPORTANT POINTS

OPTICAL FIBER SOURCES (DESIRABLE PROPERTIES)

AMPLITUDE MODULATION Vs FREQUENCY MODULATION (ADVANTAGES AND DISADVANTAGES)

PULSE CODE MODULATION (PCM) [ADVANTAGES AND DISADVANTAGES]

SAMPLING THEOREM AND RECONSTRUCTION (SAMPLING AND QUANTIZATION)

SUPERPOSITION THEOREM (BASICS, SOLVED PROBLEMS, APPLICATIONS AND LIMITATIONS)

Digital Modulation Techniques (ASK, FSK, PSK, BPSK)/ Amplitude, Frequency and Phase Shift Keying

Conventional AM Vs DSB-SC Vs SSB-SC Vs VSB (Comparison of AM Systems)

Quadrature Amplitude Modulation (QAM)/ QAM Transmitter and QAM Receiver Block Diagram

Single-Mode Optical Fiber Advantages

What are Microwaves and their Applications (Uses) in various fields

Microwaves Properties and Advantages (Benefits)

Basic Structure of Bipolar Junction Transistor (BJT) - BJT Transistor - Working and Properties

Polar Plots of Transfer Functions in Control Systems (How to Draw Nyquist Plot Examples)

Generation of Binary Phase Shift Keying (BPSK Generation) - Block Diagram of Binary Phase Shift Keying (BPSK)

Low Level and High Level Modulation Block Diagram (AM Transmitter Block Diagram)

Block Diagram of CRO (Cathode Ray Oscilloscope), Components of CRO and CRT with Structure and Working

Slope Overload Distortion and Granular (Idle Noise), Quantization Noise in Delta Modulation

Frequency Translation/Frequency Mixing/Frequency Conversion/Heterodyning (Basic Concepts and Need)

Quadrature Phase Shift Keying Modulation (QPSK) Basics, Waveform and Benefits

Pulse Code Modulation (PCM) Vs Differential Pulse Code Modulation (DPCM)


Rules of Divisibility (Divisibility Rule for 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11) with Examples

In this Post we will discuss Divisibility Rules for 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11 in detail with the help of examples. So go through this post to clear all your concepts about rules of divisibility


Divisibility Rule for 2

A number is divisible by 2 when the digit at ones place is 0, 2, 4, 6 or 8.
For example- 12, 16, 286, 340 etc. are divisible by 2.

Divisibility Rule for 3

A number is said to be divisible by 3, when the sum of its digits is divisible by 3.
For example- 210, 156 etc. are divisible by 3, because sum of digits of both of these numbers is divisible by 3.
2 + 1 + 0= 3, which is divisible by 3
Similarly, 1 + 5 + 6 = 12, which is also divisible by 3. 
So here we see that sum of digits of the number is divisible by 3 therefore the whole number is divisible by 3.

Divisibility Rules for 4

A number is divisible by 4, if the number formed with it's last two digits is divisible by 4.
For example- 18232 is divisible by 4, because the last two digits of this number i.e. 32 is divisible by 4. Therefore the whole number, 18232 is divisible by 4.

Divisibility by 5

A number is said to be divisible by 5, when the digit at ones place is either 0 or 5.
For example- 150, 31820, 34355 are all divisible by 5, because these numbers have 0, 0 and 5 respectively at their units places.
But Numbers such as 124, 386, 259 are not divisible by 5.

Divisibility Rule for 6

A number is divisible by 6, if it is divisible by both 2 and 3.
Example- 948 is divisible by 6, as it is divisible by both 2 (at units place it has 8) and 3 (9 + 4 + 8= 21, which is divisible by 3)
But the number 35378 is not divisible by 6, since it is divisible by 2 but not divisible by 3.

Divisibility Rule of 7

A number is divisible by 7, when the difference between twice the digit at ones place, and the number formed by the remaining digits is either 0 or a number divisible by 7. Let's understand the divisibility rule of 7 with an example-
Example- 658 is divisible by 7 because, 65-(2x8)=65-16= 49 is divisible by 7. Therefore this number is divisible by 7.

26 Jun 2018

Types of Numbers (Natural, Whole, Integer, Rational, Irrational, Real, Imaginary, Complex Numbers)

Following is the Classification of various types of numbers-

Natural Numbers (N)

If N is a set of natural numbers, then we can write the set of natural numbers as N={1,2,3,4,5,6...}. So natural numbers are simply the counting numbers.


Whole Numbers (W)

If w is the set of whole numbers, then whole numbers can be written as W={0,1,2,3,4...},
So it is clear that if we add 0 in the set of natural numbers then we get the set of whole numbers.


Integers (I)

If we represent the set of integers by I, then we can write I={ ...-3, -2, -1, 1, 0,1, 2, 3...}
Here note that, {1,2,3...} is the set of positive integers while, {...-1, -2, -3} is the set of negative integers. But '0' is neither positive number nor negative number.


Rational Numbers (Q)

Rational numbers are the numbers, that can be expressed in the form of p/q, where both p and q are integers and q is not equal to zero.
Following are the examples of Rational numbers-
0, 4, -4, 3/4, -5/7 etc.
It is very interesting to note here that between any two rational numbers, there exist infinite number of rational numbers.


Irrational Numbers

Non recurring and non terminating decimals are called has irrational numbers. Unlike rational numbers, irrational numbers cannot be expressed in the form of p/q. 
Irrational numbers are all the real numbers which are not rational numbers.
Some examples of irrational numbers are-
√3, √5, √7, √29...


Real Numbers

On combining rational numbers and irrational numbers we get set of real numbers.
In other words, a real number is a value of a continuous quantity that can represent a distance along a line.
Ex. 2, -3, 3/4, √3, √5...

RRC Central Railway Recruitment 2018 (Apprentice Vacancies 2018)

RRC Central Railway Recruitment 2018


(Railway Recruitment Cell, Central Railway, Mumbai)

Complete Details of this notification is given below-

Post Name- 
Apprentice

Total no. of Vacancies in RRC Central Railway Recruitment 2018- 
2573 post

Important Dates for RRC Central Railway Recruitment 2018- 
Starting Date - 26 June 2018
Last Date – 25 July 2018
Last Date for Fee Payment – 25 July 2018
Merit List – Will be Declared Soon

25 Jun 2018

Tamilnadu Govt. Jobs 2018/ AAVIN Recruitment 2018 (Sr Factory Assistant Posts, Apply Online for 275 Posts)

Tamil Nadu Cooperative Milk Producers Federation Ltd. (Aavin) has released a notification for the recruitment of Senior Factory Assistants with total number of vacancies of 275 posts. Interested candidates may apply for the post online before 16 July 2018.



The details of this notification is given below-

Post Name- TN Cooperative Milk Producers Federation Ltd Sr Factory Asst Online Form 2018

Total no. of Vacancies- 275 Posts

23 Jun 2018

Largest Deserts in the World

Here are the Largest Deserts in the world, their Area and Location and also some interesting facts about these great deserts.


desert pic, desert image, death valley pic



1. Antarctica Desert

Antarctica is the largest desert in the world, which is located around the South Pole. The total area covered by the Antarctica desert is 5.5 million square miles !!! Antarctica is the coldest continent and has highest average elevation in comparison to any other continent on the earth.
The temperature of Antarctica in winters may fall to -89 degree Celsius. No permanent residents are found in Antarctica because of too low temperature, but temporary residents are present in small number.

2. Arctic Desert

With an area of about 5.5 million square miles, arctic desert is the second largest desert in the world. This desert comes under Canada, Denmark, Norway, Russia, Sweden and the USA. Winter temperature may fall to  -40 degree Celsius.

Top 10 Largest Airlines in the World (Top 10 Airlines in the World by Revenue and Brand value)

In this post we will see some interesting facts about world's largest airlines. We can define world's largest airlines in different ways like-
American Airlines Group- It is  is the largest airline in the world by revenue, profit, fleet size, and passengers carried.
Lufthansa Group- It is the largest airline in the world by number of employees that work here.
Delta Air Lines- Delta Air Lines is the biggest by assets value and market capitalization.
Turkish Airlines- This airline is the largest in the world by number of countries served.
FedEx Express- By freight tonne-kilometers, it is largest.

So lets get more information here about World's largest airlines-

airlines, large airlines


Largest Airlines in the World by "Airline Companies Revenue"


American Airlines Group

Rank                        Country            Revenue (US$B) 
               1                       United States           41.0

18 Jun 2018

Top 25 Amazing and Cool facts about United States of America (USA)

United States Facts

The official name of the USA is the United States of America. The USA is a country that is located in North America having a population of more than 325 million. United States is the third most populous country in the world behind India and China and also third largest by area. The area of the USA is nearly 3 million square miles. This country has a federal presidential constitutional Republic Government.
Washington DC is the capital of USA and the largest city of the United States is New York. The official currency of this country is the United States dollar.
Now let's look at some amazing facts about states of America-

25 Cool Facts about United states of America (USA)

Statue of Liberty ,New York City, United States of America (USA) 

#1. The Pentagon is the largest office building in the world.

Quadrature Phase Shift Keying Modulation (QPSK) Basics, Waveform and Benefits

What is Quadrature Phase Shift Keying (QPSK) Modulation

In the last posts we have discussed ASK, FSK and BPSK i.e. Amplitude Shift Keying, Frequency Shift Keying and Binary Phase Shift Keying. In this post, we are going to discuss Quadrature Phase Shift Keying (QPSK). It is also a kind of phase shift keying but it is different from the binary phase shift keying.

Watch the complete Video Here-

 

So here we will understand what we mean by QPSK and why it is called as Quadrature Phase Shift Keying? what is 'Quadrature' here? and what is 'binary' in binary phase shift keying. We will also see the waveform of QPSK in this post and how it is formed. Here you will also get an idea about the benefits of QPSK over other digital modulation techniques.


🌓READ THIS ALSO:-
#Digital Modulation Techniques (ASK, FSK, PSK, BPSK)/ Amplitude, Frequency and Phase Shift Keying

How QPSK is different from ASK, FSK and BPSK

Actually we have seen in other posts on ASK, FSK, and BPSK that in these digital modulation techniques, the carrier wave assumes one of two possible states (symbols). Actually each discrete state of the carrier is called as symbol.

17 Jun 2018

Pulse Code Modulation (PCM) Vs Differential Pulse Code Modulation (DPCM)

Following are the differences between Pulse Code Modulation (PCM) and Differential Pulse Code Modulation (DPCM) based on the Following Parameters-


1. Number of Bits

PCM- It can use 4, 8 or 16 bits per sample
DPCM- Bits can be more than one but are less than PCM.


2. Transmission Bandwidth

PCM- Bandwidth required is very high as number of bits are high
DPCM- Bandwidth required is lower than PCM.



Digital Modulation Techniques (Coherent and NonCoherent Digital Modulation Techniques)

Coherent Vs Non Coherent Modulation (Introduction)

On the Basis of presence of Phase-Recovery circuit, we can classify digital modulation techniques into coherent or non coherent techniques.

Watch the Complete Video Here-

 

The job of the phase recovery circuit is to keep the oscillators supplying locally generated carrier wave at the receiver; in synchronizm to the oscillator supplying carrier wave at the transmitting end.
Actually, We use carrier waves at the transmitting and receiving ends both and for coherent detection these two Carriers should be in synchronism. Here synchronism means, synchronization in both frequency and phase.

15 Jun 2018

Microwaves Properties and Advantages (Benefits)

In this post we will discuss what are microwaves, their properties and various advantages.

What are Microwaves ?

Actually microwaves are nothing but electromagnetic waves, and they are called as microwaves because the wavelength of microwaves is small i.e. Micro, that's why it is known as 'Microwaves'.
Now let's discuss the properties of microwaves-

Watch the Complete Video here-


Properties of Microwaves

1. High Bandwidths (BW) Availability in Microwaves

Microwaves have larger bandwidth (1 gigahertz to 1000 gigahertz) in comparison to the common bands like Medium Wave (MW), Short Wave (SW), and Ultra High Frequency waves (UHF). Therefore more information can be transmitted due to high bandwidth availability in microwave frequencies.

14 Jun 2018

What are Microwaves and their Applications (Uses) in various fields

What are Microwaves (Introduction) 

Today we will understand what are different applications of microwaves, but before knowing applications of microwaves, I would like to tell you what are microwave? Microwaves are Electromagnetic Waves (EM) having frequencies in the range from 1 GHz to 1000 GHz.

Watch the Complete Video here-

 

To give you an idea, it is important to understand that signals from AM radio stations are at 1 MHZ,
And for FM radio stations at 100 MHZ.
Here we are dealing with 1 GHz to 1,000 GHz of range.
These are called as microwaves because the word micro comes from the word tiny (small).

13 Jun 2018

Quadrature Amplitude Modulation (QAM)/ QAM Transmitter and QAM Receiver Block Diagram

In this post, we will discuss the Quadrature Amplitude Modulation (QAM). Here we will see, the basic concept of quadrature amplitude modulation and why it is known as quadrature amplitude modulation. The block diagram of QAM transmitter and receiver also has been explained here.

Watch the Complete Video Here-

 

Introduction of Quadrature Amplitude Modulation (QAM)

Quadrature Amplitude Modulation (QAM) can be used, either with analog signals or digital signals. If the message signal is analog in nature, then we use it with Amplitude Modulation (AM) but when the message signal is in digital form, then Amplitude Shift Keying (ASK) is used.

Single Mode Optical Fiber Advantages

In this post, we will see various advantages that are offered by the Single Mode Fibers (SMF). So let's discuss here these advantages one by one-

1- The single mode fibers provide the greatest transmission bandwidth in comparison to other kinds of optical fibers.

🌓READ THIS ALSO:-
#OPTICAL FIBERS IN COMMUNICATION: COVERS ALL IMPORTANT POINTS


2- The losses in case of single mode fibres are minimum, as we know that in all kinds of optical fibers, losses are nearly negligible due to Total Internal Reflection (TIR) phenomena. But these losses are further reduced in single mode fibers because of the presence of only one mode.

Watch the Complete Video Here

 

 3- Quality of transmission is superior in single mode fibers, because modal noise is absent in these fibers. As it is clear by the name itself that single mode fibers contain only one mode while multimode fibers contain multiple modes. Because of this single mode, in single mode fiber there is no interference due to other modes, therefore quality of transmission is better.

9 Jun 2018

Digital Modulation Techniques (ASK, FSK, PSK, BPSK) - Amplitude, Frequency and Phase Shift Keying

In this post we will discuss three kinds of digital modulation techniques that are- Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK) and Phase Shift Keying (PSK).

So first of all let's understand, what is modulation?

Digital Modulation Techniques (ASK, FSK, PSK, BPSK) Video




What is Modulation- 

Modulation is a process, where some characteristic of the carrier wave (amplitude, frequency or phase) is varied in accordance with the instantaneous value of the modulating (message or baseband) signal.
So if amplitude of the carrier wave is varied, then it is called as amplitude modulation (AM), but if frequency or phase of the carrier wave is varied, according to the instantaneous value of the modulating signal, then it is known as frequency modulation (FM) or phase modulation (PM) respectively.

So now let's Understand the basic difference between continuous wave modulation and digital modulation-

Difference between Continuous Wave Modulation and Digital Modulation 


Amplitude Modulation (AM), Frequency Modulation (FM) and Phase Modulation (PM) are the examples of Continuous Wave (CW) modulation, while Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK) and Phase Shift Keying (PSK) are examples of Digital Modulation Techniques. The basic difference between continuous wave Modulation and digital modulation techniques is based on the nature of message signal (modulating signal).

🌓READ THIS ALSO:-
#ADVANTAGES AND DISADVANTAGES OF DIGITAL COMMUNICATION SYSTEM

In continuous wave modulation, the message signal is of analog nature but in digital modulation, the message signal is of digital nature (Binary or M-ary encoded version).
In both of these modulation techniques, the carrier wave is of analog form.
Here it is interesting to note that, the three forms of digital modulation techniques that is ASK, FSK and PSK are analogous to AM, FM and PM of continuous wave modulation respectively.

So now let's discuss each digital modulation technique (ASK, FSK and PSK) in detail-

Amplitude Shift Keying (ASK)


In ASK, the amplitude of the carrier wave is changed (switched) according to the digital input signal (modulating signal). Therefore amplitude shift keying is analogous to Amplitude Modulation (analog modulation).
ASK is analogous to AM, because in Amplitude Modulation (AM), amplitude of the carrier wave is changed according to the instantaneous value of the modulating (message) signal, in the same way in ASK also, the amplitude of the carrier wave is switched (varied) according to the instantaneous value of the modulating signal (digital input signal). The difference is only of the nature of the modulating signal. In amplitude modulation, the modulating signal is of analog kind but in digital modulation, it is a stream of digital bits.

🌓READ THIS ALSO:-
#PULSE CODE MODULATION (PCM) [ADVANTAGES AND DISADVANTAGES]

Now Let's understand the concept of amplitude shift keying (ASK) with the help of an example.
Look carefully the image shown below-


Amplitude Shift Keying, ASK, ASK Waveform, Amplitude Shift Keying (ASK) Waveform
Amplitude Shift Keying (ASK) Waveform

Here in this image observe that we are going to modulate a sinusoidal carrier wave (shown in green colour), with the digital input signal (0 1 1 0 0 1).
This image also shows the ASK waveform (modulated signal).
So now it's time to understand, how this amplitude shift keying takes place.
In amplitude shift keying, we change the amplitude of this sinusoidal carrier wave according to the digital input signal which is acting as modulating signal (message signal) here.
So the basic concept is, we do not transmit the carrier wave when the digital input signal is '0', and transmit the sinusoidal carrier as it is, for digital input signal '1'.

🌓READ THIS ALSO:-
#Quadrature Amplitude Modulation (QAM)/QAM Transmitter and QAM Receiver Block Diagram

You can observe this phenomena in the image carefully, that in this example, we have digital input signal '0', at three places, so for these three digital '0', no carrier signal has been transmitted. But for binary '1' at three places, the full carrier wave has been transmitted without any change.
Here the amplitude of the sinusoidal carrier wave is switched, as per the digital input signal. The carrier wave is either not transmitted or transmitted for digital input signal '0' or '1' respectively. That is why amplitude shift keying (ASK) is also called as "ON - OFF Keying (OOK)".
Now we will discuss the Frequency Shift Keying (FSK)

Frequency Shift Keying (FSK)


If the frequency of sinusoidal carrier wave is varied (switched) as per the digital input signal, then it is known as the frequency shift keying (FSK). It is analogous to frequency modulation (analog modulation).
The reason behind why FSK is analogous to FM, is....
In Frequency Modulation (FM), the frequency of the carrier wave is varied according to the instantaneous value of the modulating signal, in the same way in frequency shift keying also, the frequency of the sinusoidal carrier wave is varied (switched) as per the digital input signal. The difference is only of the nature of the modulating signal. In FM the modulating signal is of analogue nature while in FSK modulating signal is digital.

🌓READ THIS ALSO:-
#Watch large Collection of Engineering Video Lectures Here-

Now to understand the concept of frequency shift keying, look at the image shown below carefully-


Frequency Shift Keying, FSK, FSK Waveform, Frequency Shift Keying (FSK) Waveform
Frequency Shift Keying (FSK) Waveform

This image shows three parts-
#Digital Input signal (0 1 1 0 0 1)
#Sinusoidal carrier wave and
#FSK waveform

So here the basic purpose of Frequency Shift Keying (FSK), is to modulate (change/switch) the frequency of the carrier wave, according to the digital input signal.
Now observe the image, the places where digital input '0' is to be transmitted; the frequency of the sinusoidal carrier is decreased but when we transmit '1'; the frequency of the carrier wave is increased.
(Frequency is the number of cycles passed per second, or 1/Time period).
So in Frequency Shift Keying (FSK), we have two types of frequencies of the carrier wave, low frequency for the transmission of '0' and high frequency for the transmission of '1'.
In this way, in Frequency Shift Keying (FSK), the information of the digital input signal is present in the frequency variations of the carrier wave. That is why it is known as frequency shift keying.
Now let's discuss the Phase Shift Keying (PSK)

Phase Shift Keying (PSK)


In phase shift keying, phase of the carrier wave (analog) is varied as per the digital input signal. Phase shift keying is analogous to Phase Modulation (analog phase modulation).

🌓READ THIS ALSO:-
#PULSE MODULATION TECHNIQUES (PAM, PWM, PPM, PCM)

The phase shift keying is very much similar to Phase Modulation (PM), because in both of these modulation techniques, the phase of the carrier wave is changed, according to the instantaneous value of the modulating signal. The difference is only of the nature of the modulating signal. In phase modulation, the modulating signal is analog but in case of phase shift keying, modulating signal is of digital nature.
The carrier wave is of analogue kind in both of these modulation techniques.
Now we will understand the basic concept of Phase Shift Keying (PSK), with the help of an example shown in the image given below-


Phase Shift Keying, PSK, PSK Waveform, Phase Shift Keying (PSK) Waveform
Phase Shift Keying (PSK) Waveform

The Image contains three parts-
#The digital input signal (011001)
#The sinusoidal carrier wave (analog)
#PSK waveform

Now let's understand the basic concept, how the phase shift keying takes place-
In Phase Shift Keying (PSK), the phase of the carrier wave is changed (switched) according to the digital input signal. Therefore the information of this digital input signal is present in the phase shift variations of the carrier wave.

Now observe the image carefully-
Here we will Try to understand the concept of PSK with the help of an example given in this image. 
Notice here that, whenever the digital input changes the bit (either from '0' to '1' or from '1' to '0'), a phase shift of 180 degrees (π) takes place in the carrier wave. But no phase change occurs when there is no change in the digital bit.
In this image, observe; the phase shift of 180 degrees takes place in the carrier wave at three places. At all these three places, the digital input bit has either change from '0' to '1' or from '1' to '0'. No phase shift takes place when two two successive (back to back) 1's or two successive 0's are to be transmitted (as per the image). Hence we get the PSK waveform in this way. 

This was all about three kinds of digital modulation techniques, amplitude shift keying, frequency shift keying and phase shift keying.

Read More-

Go To HOME Page
   
FREQUENCY SPECTRUM OF AMPLITUDE MODULATION (WAVEFORMS AND EQUATIONS DERIVATION)

AMPLITUDE MODULATION (TIME DOMAIN EQUATIONS AND WAVEFORMS)

ADVANTAGES AND DISADVANTAGES OF DIGITAL COMMUNICATION SYSTEM

ADVANTAGES OF OPTICAL FIBER COMMUNICATION

STEP INDEX OPTICAL FIBER (MULTIMODE AND SINGLE MODE STEP INDEX FIBERS)

PULSE MODULATION TECHNIQUES (PAM, PWM, PPM, PCM)

OPTICAL FIBER: STRUCTURE AND WORKING PRINCIPLE

PULSE AMPLITUDE MODULATION (PAM)

COMPARISON OF PAM, PWM, PPM MODULATION TECHNIQUES

PULSE WIDTH MODULATION (PWM)

CONTINUOUS TIME AND DISCRETE TIME SIGNALS (C.T. AND D.T. SIGNALS)

NEED AND BENEFITS OF MODULATION

PULSE POSITION MODULATION (PPM)

OPTICAL FIBERS IN COMMUNICATION: COVERS ALL IMPORTANT POINTS

OPTICAL FIBER SOURCES (DESIRABLE PROPERTIES)

AMPLITUDE MODULATION Vs FREQUENCY MODULATION (ADVANTAGES AND DISADVANTAGES)

PULSE CODE MODULATION (PCM) [ADVANTAGES AND DISADVANTAGES]

SAMPLING THEOREM AND RECONSTRUCTION (SAMPLING AND QUANTIZATION)

SUPERPOSITION THEOREM (BASICS, SOLVED PROBLEMS, APPLICATIONS AND LIMITATIONS)

Digital Modulation Techniques (ASK, FSK, PSK, BPSK)/ Amplitude, Frequency and Phase Shift Keying

Conventional AM Vs DSB-SC Vs SSB-SC Vs VSB (Comparison of AM Systems)

Quadrature Amplitude Modulation (QAM)/ QAM Transmitter and QAM Receiver Block Diagram

Single-Mode Optical Fiber Advantages

What are Microwaves and their Applications (Uses) in various fields

Microwaves Properties and Advantages (Benefits)

Basic Structure of Bipolar Junction Transistor (BJT) - BJT Transistor - Working and Properties

Polar Plots of Transfer Functions in Control Systems (How to Draw Nyquist Plot Examples)

Generation of Binary Phase Shift Keying (BPSK Generation) - Block Diagram of Binary Phase Shift Keying (BPSK)

Low Level and High Level Modulation Block Diagram (AM Transmitter Block Diagram)

Block Diagram of CRO (Cathode Ray Oscilloscope), Components of CRO and CRT with Structure and Working

Slope Overload Distortion and Granular (Idle Noise), Quantization Noise in Delta Modulation

Frequency Translation/Frequency Mixing/Frequency Conversion/Heterodyning (Basic Concepts and Need)

Quadrature Phase Shift Keying Modulation (QPSK) Basics, Waveform and Benefits

Pulse Code Modulation (PCM) Vs Differential Pulse Code Modulation (DPCM)


Conventional AM Vs DSB-SC Vs SSB-SC Vs VSB - Comparison of AM Techniques - Types of Amplitude Modulation

Here we will discuss, What is Amplitude Modulation and various Amplitude Modulation Techniques.
The amplitude modulation systems may be of different types. Here the comparison of a Amplitude Modulation Systems (AM systems) has been discussed.

What is Amplitude Modulation (AM)

Amplitude Modulation may be defined as a system, where the maximum amplitude of the carrier wave varies, according to the instantaneous value (amplitude) of the modulating (message or baseband) signal.

Types of Amplitude Modulation

1- Conventional Amplitude Modulation (Conventional AM)
2- Double SideBand - Suppressed Carrier (DSB-SC)
3- Single SideBand - Suppressed Carrier (SSB-SC) and
4- Vestigial SideBand (VSB)

Amplitude Modulation Techniques Video


 

So let's understand the basic concept of all these various Amplitude Modulation systems and their comparison. Here we will also discuss where these Amplitude Modulation systems are used i.e. their applications in various fields.

So let's starts 
Let me first tell you, what these various Amplitude Modulation Techniques mean-

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Conventional Amplitude Modulation (Conventional AM)


In this modulation system the amplitude modulated signal contains carrier wave and 2 sidebands (upper side band and lower side band)

Double Sideband Suppressed Carrier (DSB-SC)


As clear by the name itself, the double sideband suppressed carrier contains only 2 sidebands and the carrier is suppressed (not present).

Single Sideband Suppressed Carrier (SSB-SC) 


The single sideband suppressed carrier contains only one sideband and no carrier is present. In this one sideband is suppressed.

Vestigial Sideband (VSB) 

In Vestigial sideband modulation, instead of rejecting one sideband completely (like SSB), a gradual cutoff of one side band is allowed.

Comparison of AM Modulation Techniques (Conventional AM vs DSBSC vs SSBSC vs VSB


1.Demodulation (detection) of conventional AM is easier than that of double sideband suppressed carrier and single sideband amplitude modulated systems. We can use rectifier or envelope detector to demodulate conventional amplitude modulation. Not only the demodulation of conventional AM is easy but also it is less expensive in comparison to other amplitude modulated systems.

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2. Conventional AM can be used for broadcasting services, because it is possible to produce conventional AM signals at high power levels.

3- Double sideband suppressed carrier and single sideband systems require lesser power to transmit the same information in comparison to conventional amplitude modulation (AM).
As we know that conventional AM contains two sidebands along with the carrier wave. Nearly 2/3rd of power is required to transmit this carrier wave and rest 1/3rd for the transmission of two sidebands. But it is important to note here that, the information is present only in the sidebands, the carrier contains no information. Although one sideband contains the full information and the other sideband is just the replica of it. So from this power point of view, conventional Amplitude Modulation is least efficient in comparison to other amplitude modulation techniques (schemes/systems)
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4- DSB-SC and SSB modulation systems are used in point-to-point communication while conventional AM finds application in public broadcasting systems. The double sideband - suppressed carrier and single sideband - suppressed carrier are but are much more Complex and expensive techniques. And it is always desirable for a broadcasting system to be very simple and less expensive. Because a broadcasting system contains 1 transmitter and serves millions of people while in point-to-point communication, we have 1 transmitter and few receivers.

5- following is the order of bandwidth required in various Amplitude Modulation systems-
Conventional AM > DSB-SC > VSB > SSB
It is clear from this order of bandwidth required that the single sideband is the most efficient modulation scheme.
It should also be noted here that, the bandwidth required for single sideband is only half of the bandwidth required for double sideband suppressed carrier and the bandwidth of vestigial sideband is nearly 25% higher than that of the single sideband but much lesser than double sideband - suppressed carrier.

6- Vestigial SideBand (VSB) signal generation is easiest in comparison to other techniques like conventional AM, double sideband - suppressed carrier and single sideband.

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7- VSB modulation scheme is used for the transmission of television signals while SSB is used for long distance transmission of voice signals, because it allows large spacing between the repeaters. The conventional Amplitude Modulation finds application mostly in public broadcasting services as it can be produced at higher power levels in comparison to other amplitude modulation techniques.


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