Amplitude modulation and demodulation of harmonic signal. Am modulation and demodulation with circuit and output. Double sideband large carrier dsblc modultion for general message signal mt. Modulation makes my voice to exchange band from 0 to 20004000hz. In singlechannel efield sensing, the carrier we transmit is m, the sensed value is a, and the noise is n vectors. We can define amplitude modulation by saying that a modulating signal, should produce an am wave of the form well use s instead of v or e to indicate that were talking about a modulated quantity and that it can be either a field or a voltage. Students will explore the mathematical theory behind amplitude modulation and use the analog discovery 2 to visualize the effects of amplitude modulation in the time and frequency domains. Pulse amplitude modulation pam, quadrature amplitude modulation qam 12. Amplitude modulated signal can be represented by the following equation. In part i you will learn how to design an amplitude modulator am and in part ii you will be able to demodulate an am signal.
Adaptation of the information signal to the transmission channel. For amplitude modulation, we use simple and low cost circuit. It requires that the amplitude of the dc a part of a t is equal to the amplitude of the ac part a. There are no amplitude scales shown, but you should be able to deduce the depth of modulation 1 by inspection. Process by which a property or a parameter of a signal is varied in proportion to a second signal. Source called v1 generates the message to be transmitted. Actually, am modulation creates two copies of the original signal, one at 20003000hz band and another at 30004000hz. This block diagram consists of the differentiator and the envelope detector.
Ammeter ampere amplifier amplitude distortion amplitude modulation. Amplitude modulationwhich of course is the origin of the term am radiovaries the amplitude of the carrier according to the instantaneous value of the baseband signal. Ee4512 analog and digital communications chapter 6 chapter 6 analog modulation and demodulation amplitude modulation pages 306309. The idea is simple, though the notion that it can be used to modulate signals for transmission was hardly obvious before its discovery. Then, students will use labview to program an am demodulator and use it to explore and visualize the.
Frequency division multiplexing, fdma amplitude modulation and demodulation. To study and perform phase shift keying 10 modulation and. Message signal embed into the amplitude of carrier simple am is also called. Amplitude modulation am is defined as modifying the amplitude of the carrier wave according to the message or information signal. Signal waveform of amplitude modulation let the amplitude of the audio signal be mt a m cos. Design and implementation of amplitude modulator and demodulator introduction communication is the most important needs from the very beginning of civilization. Amplitude modulationdemodulation in matlab file exchange. Because of amplitude modulation wavelength, am signals can propagate longer distances. I find am a fascinating topic, not least because it has a quite unexpected result. Basic concept of modulation the information source typically a low frequency signal referred to as the baseband signal carrier a higher frequency sinusoid example. At the receiving station, the message signal is extracted from the modulated carrier by demodulation. Bikram modak departmentcomputer science and engineering semester4th roll no.
Bpsk, qpsk, msk frequency shift keying, fsk quadrature amplitude modulation, qam. Am modulation and demodulation cypress semiconductor. Content introduction what is modulation types of modulation amplitude modulation modulation index amplitude demodulation circuit diagram about project conclusion 3. 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. Nestor project nevod nims nina accelerator nistf1 nmssm nnpdf. Demodulation is defined as extracting the original informationcarrying signal from a modulated carrier wave. Am modulation and demodulation with circuit and output 1. In amplitude modulation, the amplitude signal strength of the carrier wave is varied in proportion to that of the message signal being transmitted.
Then, students will use labview to program an am demodulator and use it to explore and visualize the effects. Amplitude modulation is defined as the process in which the amplitude of the carrier wave ct is varied about a mean value, linearly with the baseband signal. The resulting signal from the process of amplitudemodulation is called amplitude modulation signal of simply am wave. Here is the circuit used for modulation and its simulation.
Since amplitude modulation signal utilizes audio signal to modulate carrier signal, which means the variation of carrier signal amplitude is followed by the change of audio signal amplitude. The purpose of this lab is for you to gain familiarity with the concepts of amplitude modulation and demodulation. Introduction modulation in the modulation process, some characteristic of a highfrequency carrier signal bandpass, is changed according to the instantaneous amplitude of. Then as the audio signal amplitude is changed to 150 mvpp, the percentage modulation dropped to around 30%. From modulation the signal carrier we are provided with amplitude modulation am, frequency modulation fm, or phase modulation pm. Modulation and demodulation this chapter describes the essential principles behind modulation and demodulation, which. To be exact, this modulation is named amsc supressed carrier, for a reason that i will clarify a bit later. There are different types of modulation and so are demodulators. This lab introduces students to communications theory with amplitude modulation and demodulation. Hence the objective of amplitude demodulator is to take out the variation envelop detection from modulated. This means, it converts the frequency variations of fm wave into the corresponding voltage amplitude variations of am wave. Pulse position modulation ppm is an analog modulation scheme in which, the amplitude and the width of the pulses are kept constant, while the position of each pulse, with reference to the position of a reference pulse varies according to the instantaneous sampled value of the message signal. Is there a way i can vary it, say, to 100% modulation depth. This conforms to the expectation as the maximum and minimum peak of the modulated signal waveform varies proportional to the amplitude of the modulating signal.
Modulation allows us to transmit multiple signals in the same medium i. Indian institute of technology kanpur ee 381 electrical. Analog modulation and demodulation amplitude modulation pages 306309. Amplitude modulation article about amplitude modulation.
Amplitude modulation am works by varying the amplitude strength of a carrier signal, in proportion to amplitude of a modulation signal that is to be transmitted to one or more receivers. Vectors and modulation cse 466 interfacing 3 spose m and n are orthogonal unit vectors. 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. An interactive demo which enables you to both see and hear the result of multiplying a sine wave with a cosine amplitude envelope. May, 2016 am modulation and demodulation with circuit and output 1. This signal should have a carrier frequency of 20 khz and be 100 percent modulated in the frequency range from 200 to hz. Frequency and phase modulation are actually quite similar and are classified under the category of angle modulation. As we mentioned before, well use dsbc modulation because of its ease in demodulation. The original amplitude modulation is a family of modulation schemes, in which the amplitude of a. Matlab script simulating the modulating and demodulation. Demodulation is a key process in the reception of any amplitude modulated signals whether used for broadcast or two way radio communication systems.
Oct 30, 2017 amplitude modulation and demodulation. Discover the key aspects about the demodulation detection of amplitude modulated signals. From the diagram, it can be seen that the envelope of the signal follows the contours of the modulating signal. Analog communication fm demodulators tutorialspoint.
Hi, im a beginner in matlab and im just wondering whether the modulation constant. Apr 15, 2017 amplitude modulation and demodulation by. The continuous wave modulation techniques are further divided into amplitude modulation and angle modulation. Fields or signals modulated in these ways are for obvious reasons called am amplitude modulated, fm frequency modulated, or pm phase. Demodulation is the process by which the original information bearing signal, i. Hapter modulation and demodulation mit opencourseware. Ee4512 analog and digital communications chapter 6 the analytical signal for double sideband, large carrier amplitude modulation dsblc am is. 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. The depth of modulation, defined below, can be adjusted with the adder gain control g. Amplitude modulation am is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. Aly elosery october 25, 2010 this lab is divided into two parts.
Farshad lahouti january 20, 2003 winter 2003 uw, ece 318 lecture notes 2 information source signal modulator propagation channel signal demodulator information destination analog communication system analog signals may be transmitted directly via carrier modulat ion over. Communications i amplitude modulations and demodulations. What is amplitude modulation, am electronics notes. To involve data information or speech information, another wave has to be imposed known as input signal above the carrier wave. If not, what is the default depth of modulation for am here. Radio waves can carry audio, video, and digital information over great distances by using changes in a carrier waves amplitude, frequency, or phase to represent the information being transmitted. The mathematical relationship for amplitude modulation is simple and intuitive. Amplitude modulation and demodulation abstract a single tone sinusoidal signal is transmitted using amplitude modulation and is demodulated at the receivers end using an envelope detector and the attenuated signal is amplified using common source bjt amplifer. Most radio systems in the 20th century used frequency modulation fm or amplitude modulation am for radio broadcast. Each channel sharing scheme a set of basis vectors. When the modulation source is an audiofrequency oscillator and the destination is the gain of a vca in the audio signal path, we call the result amplitude modulation, or am for short. This process of imposing an input signal on a carrier wave is known as modulation.
Set g so that the sinewave peaks just fall to zero. Analog communication pulse modulation tutorialspoint. A demodulator is an electronic circuit that is mainly used to recover the information content from the modulated carrier wave. The carrier signal and y have sampling frequency fs. The modulated signal y has zero initial phase and zero carrier amplitude, resulting from a. The idea is simple, though the notion that it can be used to modulate signals. Amplitude modulation am, demodulation and their circuit. Then inner products dot products are 1 1 0 can interpret inner product as projection of vector 1 v1 onto vector 2 v2in other words, inner product of v1 and v2 tells us how much of vector 1 is there in the direction of vector 2. This type of modulation is used to transmit analog as well as digital baseband signals. To understand the theoretical foundations of analog communications as well as of doublesideband amplitude modulation and demodulation dsbam. To study and perform pulse position 6 to study and perform pulse code modulation and demodulation. This principle is at the heart of amplitude modulation. A continuouswave goes on continuously without any intervals and it is the baseband message signal, which contains the information.
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