In addition to reading the questions and answers on my site, i would suggest you to check the following, on amazon, as well. Sometimes it is necessary to digitise an analogue signal. Communication systems has used a very clever technique called modulation to increase the reach of the signals. In analog modulation, a continuously varying sine wave is used as a carrier wave that modulates the message signal or data signal. The main two types of modulation that scanner hobbyists deal with are amplitude modulation am and frequency modulation fm and the derivatives of both of these. Modulation types of modulation definition applications. Chapter 14 modulation introduction as we have seen in previous three chapters, different types of media need different types of electromagnetic signals to. Indeed, if you asked the people writing gregorian chant for an exhaustive list of the types of modulation, im guessing the list would be much shorter than if you asked, say, franz liszt.
Understand the principle of amplitude modulation know how to modulate a signal to a certain frequency know how to demodulate a signal back to the baseband can write the equation and draw block diagram for both modulation and demodulation can plot the signal spectrum after modulation and demodulation. Well explore a few different types of modulation to give you an idea. When we apply phase modulation it leads to change in frequency too. Where as digital modulations are with bit streams or symbols from computing vevices as base band signals. Multiple choice questions and answers on modulation and. Therefore, the degree of effective amplitude modulation in a system will affect some distortion parameters.
In the angle modulation, again there are two different types of modulations. Modulation enables the transfer of information on an electrical signal to a receiving device that demodulates the signal to extract the blended. Evm simulation and its comparison with ber for different. In the pulse code modulation, analog signal is reconstructed to digital signal for ease of transmission by using the analog signal samples. In music, modulation is the change from one tonality tonic, or tonal center to another. Amplitude modulation am frequency modulation fm phase modulation pm click on the links given above to know more. Am modulators base, collector, grid and plate modulators. Most radio systems in the 20th century used frequenc y modulatio n fm o r amplitude modulati on am for radio broadcast a modulat or is a device that per forms modulat ion. Or the process of modulation can be defined as varying the rf carrier wave in accordance with the intelligence or information in a low frequency signal. In pulse modulation, the carrier is in the form of pulse rather than being a sine wave as in other types of modulation. Modulation changing to a new tonal center a new tonic for more than a few chords, often with a cadence. The many types of radio frequency modulation radio.
Frequency versus amplitude modulation l amplitude modulation am l changes the amplitude of the carrier signal according to the amplitude of the message signal. Actually, it is possible to bridge these categories by combining amplitude modulation with frequency or phase modulation. Pulse code modulation is first introduced by alec reeves in the year 1937. Analog modulation delas with the voice, video and regular waves of base band signals. Modulation index is basically the ratio of amplitude of the massage signal the message we want to transmit to the amplitude of carrier signal. You may get the doubt that what is the need of modulation. Hence info is carried in the phase or frequency of the carrier.
The changes in the carrier signal are chosen from a finite number of m alternative symbols the modulation alphabet. There are mainly three basic types of amplitude modulation schemes as described below. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Types of modulation schemes used in communication systems. Amplitude modulation amplitude modulation is an increase or decrease of the carrier voltage ec, will all other factors remaining constant. Modulationtypesamplitude,frequency,phase modulation. Recall that our goal is to transmit data over a commu nication link, which we achieve by mapping the. Pdf types of modulation schemes used in communication. Modulation to reduce noise and interference some types of modulation are useful for reducing noise and interference. In both the techniques, the baseband information is converted to radio frequency signals, but in analog modulation these rf communication signals are continuous range of values, whereas in digital modulation these are prearranged discrete states. All about modulation basic concepts, signal space, constellations and phase shift keying modulations psk, qpsk, oqpsk, mpsk.
Different types of modulation techniques by dinesh thakur category. The dsb modulated signal has double bandwidth of the modulating signal. Generally, phase modulation is used for transmitting waves. Amplitudeshift keying ask frequencyshift keying fsk phaseshift keying psk all of these techniques vary a parameter of a sinusoid to represent the information which we wish to send. Learn what is modulation and why do we need it along with its definition, advantages, examples, applications, types and need of modulations by visiting byjus. Signal is defined as the useful information which is sanded by the transmitter and received by the receiver. This may or may not be accompanied by a change in key signature. Apr 09, 20 modulation is a process through which audio, video, image or text information is added to an electrical or optical carrier signal to be transmitted over a telecommunication or electronic medium. So, this kind of modulation has a vast demand than analog modulation. The types that we currently accept as types now may change, as music changes. There are three main types of amplitude modulation. So, for this reason, this modulation is also comes under the frequency modulation.
Frequency modulation is a type of modulation where the frequency of the carrier signal is varied changed in accordance with the amplitude of the message signal while the amplitude and phase of carrier signal remain constant. Multiplexingmedium access control 2 digital modulation 3 why modulate. There are two types of modulation analog and digital. The psk can be classified into two types which include the following. In amplitude modulation, the amplitude of the carrier signal is varied by the modulating signal. Modulation techniques pwm and pulse code modulation. If p o a v o 2 is the power of the unmodulated carrier wave, the power contained in all the sidebands of an fm wave is. When the phase of the signal is changed, then it affects the frequency. This chapter describes the essential principles behind. We begin our discussion of digital modulation by starting with the three basic types of digital modulation techniques.
Modulation definition need for modulation types of. In this article, we are going to briefly talk about what modulation is and the need for it. There will be zero modulation voltage across the secondary of t1. Pdf a comparative study of various digital modulation techniques. Different types of modulation techniques slideshare. The different types of modulation techniques can be classified into continuous wave. Television broadcasting is done with amplitude modulation for video signals and frequency modulation for audio. A signal is pulse code modulated to convert its analog information into a binary sequence, i. Principles of communication modulation tutorialspoint. To convert analogue signals to digital and vice versa, several types of modulation are required. There are two main types of modulation that are used in telecommunications.
There are many types of modulation so there are many. Two signals are involved in the modulation process. Recorded modulation, also called standard modulation. Modulation is a process by which some characteristics of signal such as amplitude or phase or frequency are varied in accordance with the instantaneous value of the. Amplitude shift keying, frequency shift keying, phase shift keying, differential phase shift keying, quadrature phase shift keying, minimum.
A sinusoid has three different parameters than can be varied. Two binary digits represented by two different frequencies near the carrier frequency where f 1 and f 2 are offset from carrier frequency f c by equal but opposite amounts b 2f 2 f 1. Types of modulation techniques am, fm, pm, pam, pwm, ppm. Direct modulation also referred to as phrase, static, or abrupt modulation is by far the easiest type of modulation. It is a kind of modulation where the amplitude of the carrier signal is changed in proportion to the message signal while the phase and frequency are kept constant. Modulation and demodulation medium, it would be dif. In this project, we have generated ten different types of pulse width modulation techniques for inverters. In india, radio broadcasting is done through amplitude modulation. Since the three variables are the amplitude, frequency, and phase angle, the modulation can be done by varying any one of them. They are continuous wave modulation and pulse modulation. The two forms of modulation that fall into the angle modulation category are frequency modulation and phase modulation. Modulation modulation is the process whereby some characteristic of one wave is v aried in accordance with some characteristic of another wave.
Bpsk, qpsk, msk frequency shift keying, fsk quadrature amplitude modulation, qam. Principles of communication modulation a signal can be anything like a sound wave which comes out when you shout. Modulation is the process of superimposing a low frequency signal on a high frequency carrier signal. Am works by varying the strength of the transmitted. I know a few types of modulation off the top of my head like common chord modulation and and chromatic modulation, but i was wondering how many different types of modulation. Most radio systems in the 20th century used frequency modulation fm or amplitude modulation am for radio broadcast a modulator is a device that performs modulation. Phrase modulation a modulation in which one phrase ends with a cadence in the original key, and begins the next phrase in the destination key without. This is a rectangular representation of the polar diagram. Modulation l frequency modulation fm l most popular analog modulation technique l amplitude of the carrier signal is kept constant constant envelope signal, the frequency of carrier is changed according to the amplitude of the modulating message signal.
The process of carrier signal frequency is varied according to the message signal. All about modulation part i basic concepts, signal space, constellations and phase shift keying modulations psk, qpsk, oqpsk, mpsk. This principle is at the heart of amplitude modulation. It explains what is modulation and classification of modulation. Aug 26, 2016 different types of modulation techniques 1. This video lecture discusses different types of modulation techniques. The am technique is totally different from frequency modulation and phase modulation where the frequency of the carrier signal is varied in the first case and in the second one the phase is varied respectively. Different modulation formats used in optical communication system. Chapter 6modulation techniques shandong university. In general it involves translating a baseband signal source. Amplitude modulation am is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. Different types of modulation techniques in communication. In these types of formats for a fraction of bit period the power is transmitted.
These are two different ways to add diversity to signals allowing different. Amplitude modulation definition, types, solved examples. That is whether the carrier signal is analog or digital. Digital modulation is of several types depending on the type of signal and application used such as amplitude shift keying, frequency shift keying, phase shift keying, differential phase shift keying, quadrature phase shift keying, minimum shift keying, gaussian minimum shift keying, orthogonal frequency division multiplexing, etc. As we have seen in previous three chapters, different types of media need different types. Demodulation is the opposite process of modulation. Treatment of a chord as the tonic for less than a phrase is considered tonicization modulation is the essential part of the art. Different types of modulation the two types of modulation.
If we consider the intensity modulated direct detection system uses two types of modulation formats which are non returntozero and returntozero formats. Modulation is classified to two types based on the nature of carrier signal. Quadrature amplitude modulation is the type of amplitude modulation in which two different message signals are transmitted on the same frequency carrier with a different phase shift. In pulse width modulation, there are different types of modulation for analog and digital as shown below. Modulation, analog modulation, digital modulation, am,fm. The 2nd type of modulation we are going to have a look at is phrase modulation or abrupt modulation this modulation is a sudden change of key. Here in modulation, we combine both carrier signal and message signal. When we modulate an analog signal, it is called analog modulation and when we modulate a digital signal, it is called digital modulation. Modulation, analog modulation, digital modulation, am,fm,pm.
The modulating output signal is coupled through modulation transformer t1 to the class c amplifier. The secondary winding of the modulation transformer is connected in series with the collector supply voltage vcc of the class c amplifier. Modulation is a technique in which message signal is transmitted to the receiver with the help of carrier signal. The basic types of modulation are angular mo dulation including the special cases of phase and frequency modulation and amplitude modulation. There are many modulation techniques, which are classified according to the type of modulation employed. Digital modulation methods can be considered as digitaltoanalog conversion and the corresponding demodulation or detection as analogtodigital conversion. In this type of modulation, the phase of the carrier signal varies in accordance with the message signal.
Modulations articulate or create the structure or form of many pieces, as well as add interest. Demodulation is extracting the original informationbearing signal from a carrier wave. Two principal types of multiplexing or multiple access are tdma time division multiple access and cdma code division multiple access. There are the three very common types of modulations and some less common types. To facilitate understanding of zsource inverter modulation, this paper presents a detailed analysis, showing how various conventional pulsewidth modulation strategies can be modified to switch a. Qam quadrature amplitude modulation another layer of complexity in many new systems is multiplexing. Today, however, were going to take a look at modulation in its most basic form. Communication is a process by which information is exchanged between. In particular, we discuss amplitude and frequency modulation. Process by which a property or a parameter of a signal is varied in proportion to a second signal. This technique of pivot chord modulation works best if you move to closely related keys keys that only have a few sharpsflats different from each other closely related keys.
Jean marcus, in radio remotecontrol and telemetry and their application to missiles, 1966. Carrier signal is the higher frequency wave with higher energy to carry the message signal to long dis. Modulation to overcome equipment limitations modulation is used to place signals in a portion of the spectrum where equipment limitations are minimal or most easily met. One approach to reduce this interference, known as frequencydivision multiplexing, allocates different carrier frequencies to different users or for dif. Here, the phase shift of the carrier is varied according to the amplitude of carrier wave. The microcontroller is the most efficient tool for generating various pulse width modulation techniques. In this article, you will find the study notes on types of modulation and demodulation which will cover the topics such as introduction to communication systems, amplitude and demodulation, classification of am, angle modulation and demodulation, generation of fm and pulse modulation. Sinusoids have amplitude, frequency, and phase, and thus it should come as no surprise that modulation schemes are categorized as amplitude modulation, frequency modulation, or phase modulation. Different types of modulation techniques in communication systems. Modulation is the addition of intelligence information to an electronic signal, in this case radio frequency rf waves. Mar 16, 2019 multiple choice questions and answers on modulation and demodulation. Of them all, the digital modulation technique used is pulse code modulation pcm. Request pdf evm simulation and its comparison with ber for different types of modulation to characterize the quality of wireless telecommunications system more efficiently and integrally, it.
Carrier modulation and demodulation types of analog modulation technique i. Both types of angle modulation, namely frequency modulation and phase modulation are linked because frequency is the derivative of phase, i. Digital modulation in communications systems an introduction. In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a modulating signal that typically contains information to be transmitted. In electronics and telecommunications, modulation is the process of varying one or more. This shout can be heard only up to a certain distance. Modulation allows multiplication by frequency division, a very important technique. Modulation is the process of encoding information from a message source in a manner suitable for transmission. Switching modulation has defined as the process of combining an input signal m t and a frequency carrier fc to produce an s t signal whose bandwidth is usually centred around fc. A demodulator is an electronic circuit or computer program in a softwaredefined radio that is used to recover the information content from the modulated carrier wave. Different types of modulation include both analog and digital modulations, in which the carrier wave parameters depend on the base band or message signal. Modulation mainly occurs when the characteristics of input signal i. Types of modulation techniques am, fm, pm, pam, pwm.
421 438 1504 220 738 215 280 228 1029 1418 1290 578 592 771 235 556 374 966 1368 1253 555 1383 25 510 320 1070 981 736 1049 1294 742