Demodulation is the opposite process of modulation. As the resultant is a coded pulse train, this is called as pcm. Many signals in modern communication systems are digital also, analog signals are transmitted digitally. Analog and digital pulse modulation techniques gate study. In analog pulse modulation some parameter of each pulse is modulated by a particular sample value of the message. In pulseamplitude modulation pam a pulse signal is used to sample an analog. After continuous wave modulation, the next division is pulse modulation. Communication systemsanalog modulation introduction. Pulse coded modulation pcm is a form of modulation where there is no carrier, so. 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 pulse amplitude modulation pam technique, the amplitude of the pulse carrier. In digital modulation, the modulation technique used is pulse code modulation pcm where the analog signal is converted into digital form of 1s and 0s. Whereas analog modulation schemes have been traditionally termed modulation, digital modulation schemes, otherwise identical in operation, are term keying, denoting the onoff nature of the 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. Sometimes it is necessary to digitise an analogue signal. Analog communication pulse modulation after continuous wave modulation. Digital information can be generated from a computer but the information source can also be analog, as its the case of the voice. Modulation is the process of superimposing a low frequency signal on a high frequency carrier signal. Later, well see how pulse width modulation and pulse code modulation are used in transmissions from satellites and in multichannel telephone communications. Reduced distortion and improvement in signal to noise ratios. In pulse modulation, the signal is translated to a series o. A block diagram showing the basic classification of modulation techniques is given below. Chapter 6modulation techniques shandong university. A continuouswave goes on continuously without any intervals and it is the baseband message signal, which contains the information. 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.
The general function sinusoidal waves is shown in the figure below, in which, three parameters can be altered to get modulation they are amplitude, frequency and phase. Frequency modulation the frequency of the carrier signal is proportional to the modulating. Pulse position modulation ppm is an analog modulation scheme where, the amplitude and the width of the pulses are kept constant, while the position of each pulse, and also the reference to the position of a reference pulse varies according to the instantaneous sampled value of the message signal. What is analog pulse amplitude modulation and digital. This ezed video explains modulation techniques types of modulation analog modulation digital modulation analog modulation amplitude modulation frequency modulation phase modulation. Pulse width modulation pwm, the width of the pulse represents the. So now lets discuss different types of pulse modulation techniques in detailpulse modulation can be categorized broadly into two types. The continuous wave modulation techniques are further divided into amplitude modulation and angle modulation. There are two types of modulation analog and digital. To convert analogue signals to digital and vice versa, several types of modulation are required. We can model sampling as multiplication of an analog waveform gt with an impulse train. Amplitude modulation is a type of analog modulation in which the amplitude of the highfrequency carrier signal is changing with respect to the instantaneous amplitude of the modulating signal. Pulse amplitude modulation pam pulse width modulation pwm pulse position. The analog pulse modulation can be understood with a simple example.
Pulse width modulation has many application in digital communication, power electronics, auto intensity control of street lights, speed control of dc motor and variable pwm to generate analog signal from digital signals, digital to analog converter. In pulse width modulation or pulse duration modulation, the width of the pulse carrier is varied in accordance with the sample values of message. Modulation is the process by which we map information on to a carrier. Frequency versus amplitude modulation l amplitude modulation am l changes the amplitude of the carrier signal according to the amplitude of the message signal. Modulation is the process of converting data into electrical signals optimized for transmission. We distinguish two types of analogical modulations. In pulse modulation systems, the carrier is a train of pulses rather than a continuous signal. Modulation, analog modulation, digital modulation, am,fm. First off, you have to understand what modulation refers to. Pulse duration modulation pdm or pulse width modulation pwm.
There are 3 main types of digital pulse modulation. The microcontroller is the most efficient tool for generating various pulse width modulation techniques. Analog communications 26 other modulation methods amplitude modulation the amplitude of the carrier signal is controlled by the modulating signal pitfall of am. In pulse width modulation or pulse duration modulation, the width of the pulse carrier is varied in accordance with the sample values of message signal or modulating signal or modulating voltage. Analog communication pulse modulation tutorialspoint. The am and fm radios are examples of analog data over analog medium. Or modulation is defined as the precess by which some characteristics, usually amplitude, frequency or phase, of a carrier is varied in. Modulation techniques are roughly divided into four types. Modulation definition need for modulation types of.
Ee4512 analog and digital communications chapter 6 the dsbsc am coherent receiver has a bandpass filter centered at f c and with a bandwidth of twice the bandwidth of st because of the lsb and usb. Analog and digital modulation techniques assignment 1. Pulse time modulation ptm, somewhat similar to analog phase modulation. Modulation techniques pwm and pulse code modulation. This is divided into analog pulse modulation and digital pulse modulation. Lets take a closer look at all of these pulse modulation techniques and find out how a sine wave see fig. It will also discuss some practical information about how to construct a transmitter. Pulseamplitude modulation pam, is a form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses.
Pulse modulation is a technique in which the signal is transmitted with the information by pulses. The following safety and common symbols may be used in this manual and. Pdf analog and digital modulation techniques assignment. Pulse modulation is a type of modulation in which the signal is transmitted in the. In this article we will see an introduction of pulse width modulation. Pulse modulation techniques digital signal modulation. This book will attempt to discuss some of the mathematical models and techniques used with different modulation techniques. Demodulation channel decoding is the corresponding process at the receiver of converting the received waveform into a. Digital modulation relies on digital signal processing, such as digitaltoanalog converters dacs at a receiver and analogtodigital converters adcs at a transmitter to transform analog information e. The waveform for this type of pwm is denoted as a in the above figure. The modulation concept, baseband signal, bandpass signal, message signal, carrier signal, modulated signal, modulation, types of modulation, amplitude modulation am, angle modulation, frequency modulation fm, phase modulation pm. Over the past few years a major transition has occurred from simple analog amplitude modulation am and frequencyphase modulation fmpm to new digital modulation techniques. Types of analog pulse modulation systems are options.
Analog modulation is typically used for am, fm radio, and shortwave broadcasting. In general when we talk about a digital system, we are usually talking about digital information over an analog medium. Thus, dsbsc with an analog message is called amplitude modulation, while the same dsbsc. In pulse amplitude modulation pam technique, the amplitude of the pulse carrier varies, which is proportional. In amplitude modulation, the amplitude of the carrier signal changes instantaneously with respect to the amplitude of the modulating signal. Sampling is common in all pulse modulation techniques. Pulse modulation communications university of toronto. In pulse amplitude modulation pam technique, the amplitude of the pulse carrier varies, which is proportional to the instantaneous amplitude of the message signal. Pulse modulation, october 1960 popular electronics rf cafe. Analog modulation delas with the voice, video and regular waves of base band signals. Analog modulation, digital modulation, pulse modulation, and spread spectrum method.
It has higher noise immunity when compared to other methods. Pulse amplitude modulation pulse width modulation pulse position modulation pulse code modulation pulse modulation the process of transmitting signals in the form of pulses discontinuous signals by using special techniques. It is a method of encoding and transmitting data through a certain type of signal that can be deciphered at the receiving end. Pulse modulation definition, types, block diagrams, pulse. In cw modulation schemes some parameter of modulated wave varies. In this chapter, let us discuss the following analog pulse modulation techniques. The analog pulse modulation is again classified as, 1. Types of modulation techniques am, fm, pm, pam, pwm, ppm. Analog and digital pulse modulation techniques need. Where as digital modulations are with bit streams or symbols from computing vevices as base band signals. Pdf analog,digital and pulse modulation techniques researchgate. Pulse coded modulation pcm is a form of modulation where there is no carrier, so that makes it a pure digital system.
Pdf introduction to various signal modulation techniques to have effective. Modulation allows multiplication by frequency division, a very important technique. Among the types of modulation techniques, the main classification is continuouswave modulation and pulse modulation. The analog modulation techniques are mainly classified into pulse amplitude. These modulation techniques are continuous wave modulation amplitude modulation,frequency modulation,phase modulation and pulse modulations pam, pwm, ppm, pcm. It is an analog pulse modulation scheme in which the amplitudes of a train of carrier pulses are varied according to the sample value of the message signal. Most radio systems in the 20th century used frequency modulation fm or amplitude modulation am to make the carrier carry the radio broadcast.
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