Amplitude modulation can be produced in various ways. Fleury navigation and communications navcom department of electronic systems aalborg university, dk. Lecture notes on analogue communication techniques 1. The amplitude modulation and frequency modulation are graphically shown in. What is the difference between modulation and amplifier. According to the ccitt standard, if the pcm input bit flow is 64 kilobits per second kbps 8 khz sampling x 8bit pcm. The middle graph shows the modulated carrier, where is the message signal and is the modulation factor. The only difference between pure frequency modulation 1 and phase modulation is the fact that the deviation is a function of the amplitude only of the modulating signal for pure frequency modulation while the frequency of the signal also determines the deviation for phase modulation.
It is well understood that the pulse amplitude modulation pam representation of continuous phase modulation. Modulation is a process by which the properties of one signal is made to vary the properties of another signal. Jul 02, 2018 in this video, i have explained phase modulation fm by following outlines. Digital communication systems and their modulation techniques pdf by c. Amplitude modulation a1 49 you will see in this experiment, and in others to follow, that there is no problem in generating an am signal with a depth of modulation exceeding 100%, and without.
Assume the channel attenuates the signal power by a factor of, i. Nptel video lectures, iit video lectures online, nptel youtube. Communication engineering nptel online videos, courses. Linear amplitude modulation applications april 04, 2016 by donald krambeck in this article, well delve into amplitude modulation and what its used for. Introduction to communication engineering vtunptel. Dec 29, 2017 clear inthebox structuring within the program enables you to be more creative outsidethebox. Example ofamplitudephase distortion consider the periodic rectangular pulse train of notes 992, page 6, with period t1, amplitude a1, and duration of each pulse t 0. Find powerpoint presentations and slides using the power of, find free presentations research about amplitude modulation and demodulation ppt.
Ontheamplitudeandfrequencymodulationdecomposition ofsignalsa patrick j. And briefly how do you describe amplitude modulation some. Pulse train pulse amplitude modulation jamadagni h s dcv12004 9 pulse code modulation pcm pam samples analog input low pass filter sample clock jamadagni h s da ad digitally encoded samples. Generation of amplitude modulation basic requirements. Digital communication nptel online videos, courses iit video lectures. A typical audio frequency of 3000 hz has a wavelength of 100 km and. Pdf modulation technique for software defined radio application. Modern mobile communication systems use digital modulation techniques. So, this becomes a times real part of or let me combine this i can write lie. Residual amplitude modulation method implemented at the phase quadrature frequency of a 1650nm laser diode for line shape recovery of methane. The first of these, the am transmitter, generates such high powers that its prime requirement is efficiency, so quite complex means of. Communication systems a lecture notes by mahesh lohith k. The extent of amplitude variation in am about a unmodulated carrier amplitude is measured in terms of a factor called modulation index. Amplitudes of air particle displacement, sound pressure.
The carrier frequency, fc, should be larger than the highest spectral component. Digital modulation 1 lecture notes ingmar land and bernard h. In amplitude modulation, the amplitude signal strength of the carrier wave is varied in proportion to that of the message signal being transmitted. Chemical engineering video lectures nptel video lectures. Also, we will differentiate between communication methods that do and do not use modulation. Carrier modulation allows the transmission of modulating frequencies without the use of transmission wire as a medium. This is the simplest form of modulation where the amplitude of the carrier wave is modulated by the analog signal known as. The carrier signal has frequency fc hertz and sampling rate fs hertz, where fs must be at least 2fc. A complete transmitter consists of many different stages and. Dutton ee3 winter 2004 1 ee3 lab 1 amplitude modulation and demodulation 1 lab notes a word about power. Amplitudelimiting circuit article about amplitudelimiting. Analog communications electronics and communication.
The three techniques are referred to as amplitude shift keying ask. In chapter 3 we studied the theory of amplitude modulation, but we never actually built an am transmitter. Phase modulation pm is a modulation pattern that encodes information as variations in the instantaneous phase of a carrier wave the phase of a carrier signal is modulated to follow the changing voltage level amplitude of modulation signal. Introduction to communication system introduction, orientation introduction to communication system, need for modulation, amplitude modulation, time domain and frequency domain description, power relations in am wave, square law modulator, switching. This gives us something to modulate and carry the information pattern from.
In most cases, the information signal, be it voice, video, binary data, or some other information, is normally used to modify a higherfrequency signal known as the carrier. Interesting applications of amplitude modulation of signals. Basic training as samplitude is probably new to many of you we are going to briefly cover where the controls are in this daw. Vasudevan departmentofelectricalengineering indianinstituteoftechnology kanpur208016 india version3. View and download powerpoint presentations on amplitude modulation and demodulation ppt. Sequential circuits the digital circuits we have seen so far gates, multiplexer, demultiplexer, encoders, decoders are combinatorial in nature, i. Here well use the example of a square law fet as illustrated in figure 9. Feb 09, 2017 todays signal modulation technology entirely supports a sequential approach to the transferring of digital data from transmitter to receiver. To construct a working transmitter or receiver, a knowledge of rf circuit principles is necessary. Introduction in chapters 1 and 2 you studied how to apply intelligence modulation to an rfcarrier wave. Amplitude modulation a continuouswave goes on continuously without any intervals and it is the baseband message signal, which contains the information.
Analog modulation uses mainly am amplitude and fm frequency modulations. Modulation am dbap principe chapitre 2 modulations lineaires. One is pulse amplitude modulation, so in pulse amplitude modulation what we do, suppose we have a message signal okay. For this pulse train we found a 0 a t t and a n 2 n a. Robert leese explains how the mathematics of colouring graphs can help avoid interference on your mobile phone. The comparison of ilcbased and the phase modulation approach for the detuned pulse compressor. The message signal is, for example, a function of the sound to be reproduced by a. Low frequency amplitude phase signal is added on higher one.
After you have successfully installed samplitude you should adjust the following program and project settings to make working with the program more effective. A network placed in the audio input amplifier making the. Sorry, this requires a browser that supports frames. That could be the amplitude, phase, or frequency, which result in amplitude modulation am, phase modulation pm, or frequency modulation fm.
A sinusoidal modulating waveform of amplitude 5 v and a frequency of 2 khz is applied to fm generator, which has a frequency sensitivity of 40 hzvolt. Describe phase demodulation circuit operation for the peak, lowpass filter, and conversion detectors. Nonlinear modulation theory detection, estimation, and. Linear integrated circuits amplitude modulation exam study. Timedomain description, frequencydomain description, generation of am wave. The converged input amplitude and phase waveforms are depicted in fig.
Amplitude modulation is defined as the multiplication of one timedomain signal by another timedomain signal. The phasedev argument is the phase deviation of the modulated signal in radians. Spectra have a typical trapezoidal shape in linear frequency and amplitude in decibels. The fm input signal is first subjected to a limiter in order to eliminate any amplitude modulation noise present in the signal. Loughlin and berkant tacer 348 benedum engineering hall, department of electrical engineering, university of pittsburgh, pittsburgh. We take reliable radio communications for granted, but accommodating many different users is not easy. Nptel video lectures, iit video lectures online, nptel youtube lectures, free video lectures, nptel online courses, youtube iit videos nptel courses. Amplitude modulation am is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. Calculate the frequency deviation, modulation index, and bandwidth.
The amplitude setpoint is chosen to be close to the amplitude in the phase modulation method. Modulation is the addition of information to an electronic or optical carrier signal. Linear amplitude modulation applications technical articles. Digital modulation in digital communications, the modulation process corresponds to switching or keying the amplitude, frequency, or phase of a sinusoidal carrier wave according to incoming digital data three basic digital modulation techniques amplitude shift keying ask special case of am. Telemetry applications of soqpsk and gmsk based modulation for airborne platforms. Signals are variation of electrical current or voltages over time. Questions from video lectures of nptel sl no questions video number time in minutes 1 give some examples for the communication systems which use space as the channel. In this video, i have explained importance of modulation index by following outlines. Noise produced by undesirable amplitude variations of a radiofrequency signal explanation of amplitude modulation noise. Modulation technique for software defined radio application article pdf available in australian journal of basic and applied sciences 33. Amplitude modulation and demodulation ppt xpowerpoint. Assume the lower sideband lsb is transmitted and a suitable bandpass.
The am diode detector can be built from just a diode and a few other components and as a result it is a very low cost circuit block within an overall receiver. Lecture 7 analog modulation of carriers lecture 8 amplitude modulation lecture 9 amplitude modulation lecture 10 single sideband modulation lecture 11 suppressed sideband modulation lecture 12 vsb modulation superhet receiver lecture superhet receiver etc lecture 14 practical mixerseffects of tonal lecture 15 angle. So depending on and suppose this is the pulse strength which goes like this okay, it will have uniform period of either t or ts let us say. The modulation of this data upon the transmitted signal is the same for all data sent regardless of utilization of the data by the receiver.
In addition, the pulseshaping and amplitude limiting circuits provide a digitized output devoid of any distortions in the waveform, caused by the preceding amplifier and filtering stages. In this experiment, a carrier signal and an audio modulating signal are applied to the modulator ic mc 1496 and the produced modulated waveform is observed. Soundfield quantities of a plane wave the amplitudes. Combined amplitudetime and phase modulation quantumsine. Simply put, amplitude modulation of a signal causes a signal to have sinusoidal fluctuations in amplitude. Pdf residual amplitude modulation method implemented at the. Intro to generation of ask amplitude shift keying ask in the context of digital communications is a modulation. Amplitude modulation, spectrum of am signal, the balanced modulator, the square law. In this video, i have explained amplitude modulation by following outlines. Free math problem solver answers your algebra, geometry, trigonometry, calculus, and statistics homework questions with stepbystep explanations, just like a math tutor. Frequency modulation fundamentals, august 1939 qst rfcafe. Generation of am signals, demodulation of am signals.
Bpsk, qpsk, msk frequency shift keying, fsk quadrature amplitude modulation, qam. It conveys two analog message signals or two digital bit streams, by changing amplitude of two carrier waves, using the amplitude shift keying ask digital modulation scheme, or amplitude modulation scheme for analog modulation. The amount by which the amplitude of the carrier wave increases and decreases depends on the amplitude of the information signal and is known as modulation index or depth of modulation. A product modulator is used for generating the modulated signal as shown in figure 3. Pulse compressor phase and amplitude modulation based on. The slope detection method revolves around a differentiation operation that exploits the instantaneous frequency of the fm signal. Multimedia tools downloads samplitude by magix ag and many more programs are available for instant and free download. Surendra prasad, department of electrical engineering,iit delhi. Nptel, lectures on digital communication, lesson 36 7. Pdf analog communication system pdf notes ac notes sw. The use of amplitude modulated analog carriers to transport digital information is a relatively lowquality, lowcost type of digital modulation and, therefore, is seldom used except for very lowspeed telemetry circuits. For this tutorial i am going to be using a vocal sample from a track i have that needs some tweaking.
Digital communications and signal processing iit kanpur. Lecture series on communication engineering by prof. Here you can download the free lecture notes of analog communication system pdf notes ac notes pdf materials with multiple file links to download. Introduction what is communication transmitter channel receiver a communication system process of conveying message or information transmitter modifies the message signal into a form which is suitable for transmission over channel which is achieved by modulation information source.
Importance of modulation index in amplitude modulation in. Analog communication pdf notes book starts with the topics covering introduction ac, dsb modulation, ssb modulation, angle modulation concepts, angle modulation methods, noise etc. For a plane wave, sound pressure and particle velocity are in phase. At 100% modulation, the power efficiency of am is 33. Signals have basically three basic properties amplitude phase frequency. The diode detector is the simplest and most basic form of amplitude modulation, am signal detector and it detects the envelope of the am signal. When drifts away from 0, the qchannel output will have the same polarity as the ichannel output for one direction of phase drift, and opposite polarity for another direction of phase drift. Types of modulation 6 flynnkatz 7810 analog modulation amplitude modulation, am frequency modulation, fm double and single sideband, dsb and ssb digital modulation phase shift keying.
Nonlinear modulation theory detection, estimation, and modulation theory, part ii van trees, harry l. Communication engineering communication engineering. Quadrature amplitude modulation is both an analog and a digital modulation scheme. Gate preparation, nptel video lecture dvd, electronicsandcommunicationengineering, linearintegratedcircuits, amplitude modulation, current mirror, current. The signals may or may not be complex in nature, i. Note that this is on the very low end of the recommended voltage range. Find out information about amplitude modulation noise. Ontheamplitudeandfrequencymodulationdecomposition ofsignalsa. Nptel nptel online certification course course on analog. To generate and demodulate an amplitude shift keyed ask signal and a binary fsk signal. There are two types of devices in which it may be necessary to the generation of amplitude modulation. The carrier amplitude is constant and the phase variation of the signal contains the information. Amplitude modulation double side band nptel mafiadoc. Digital communication nptel online videos, courses iit.
In this chapter, let us solve a few problems based on the concept of frequency modulation. The peak amplitude and frequency of the carrier signal remain constant, but as the amplitude of the information signal changes, the phase of the. Esd lecture 10 introduction to amplitude modulation am, modulation index, envelope distortion and over modulation lecture 11 spectrum of amplitude. So basically what we do, we modulate the amplitude of the pulses according to the input. In modulation, one characteristic of a signal generally a sinusoidal wave known as the carrier is changed based on the information signal that we wish to transmit modulating signal. Modulation is the process of modifying the characteristic of one signal in accordance with some characteristic of another signal. Mar 18, 2014 i had a hard time thinking about what to write, and i settling with amplitude modulation. Assignments signals and systems mit opencourseware. Modulation, amplitude modulation, single tone modulation of am, multitone modulation 2. Pdf telemetry applications of soqpsk and gmsk based.
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