It is still in use today in a variety of systems, including, of course, am broadcast radio. Dutton ee3 winter 2004 1 ee3 lab 1 amplitude modulation and demodulation 1 lab notes a word about power. It is often called as am and is commonly used in transmitting a piece of information through a radio carrier wave. Amplitude modulation and demodulation objective amplitude modulation am is one of the simplest methods for modulating a sinusoidal carrier wave. Switch off the experimental kit during making connections. Increase the modulated signal until an am waveform appears. Experiment 2 experiment 6 experiment dsb sc modulation and. University of north carolina at charlotte department of. Pulse amplitude modulation is the basic form of pulse modulation. When expressed as a percentage it is the same as the depth of modulation.
Amplitude modulation an overview sciencedirect topics. Quadrature amplitude modulation is widely used for carrying many digital signals, everything from wifi to mobile phone communications and very much more. The amplitude modulation am modulation index can be defined as a measure of the amplitude variation upon a carrier. Double sideband dsb is one of the easiest modulation techniques to understand, so it is a good starting point for the study of modulation. Cme312 lab manual dsbsc modulation and demodulation experiment 6 experiment 2 dsb objectives. The demod ulation is performed by an envelope detector. The demodulation of dsb am signal can be done either by using an envelope detector or by passing the amplitude modulated signal through a nonlinear device. Pulse amplitude modulation pam theory of and its applications. May 09, 2015 these videos explain you what is modulation, different kinds of modulations like amplitude modulation am and frequency modulation fm,qpsk,qam,phase modulat. Observe the time domain and frequency domain representations of am signals. This electrical signal is called the message or baseband signal.
Amplitude modulation am is similar to dsb but has the advantage of permitting a simpler demodulator, the envelope detector. Phase modulation pm is a different form of frequency modulation and the carrier is similar in appearance to a frequencymodulated carrier. Amplitude modulation or am is a method to transmit signals via electromagnetic transmission. Double sideband dsb and amplitude modulation am modules. Quadrature amplitude modulation qam pam signals occupy twice the bandwidth required for the baseband transmit two pam signals using carriers of the same frequency but in phase and quadrature demodulation. Doublesideband dsb an amplitude modulated signal in which the carrier is. In amplitude modulation the amplitude of high frequency sine wave carrier is. The binary signal when ask modulated, gives a zero value for low input while it. The merit of amplitude modulated carrier is the ease with the baseband signal can be recovered. Amplitude modulation and frequency modulation youtube. Bandwidths limit is also big advantage for amplitude modulation, which doesnt have in frequency modulation. Amplitude modulation a1 53 experiment aligning the model the low frequency term at to generate a voltage defined by eqn. Amplitude modulation am the process of combining the message signal with the carrier signal and the two sidebands. Amplitude modulation am is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave.
These videos explain you what is modulation, different kinds of modulations like amplitude modulationam and frequency modulationfm,qpsk,qam,phase modulat. Amplitude modulation early radio ee 442 spring semester. An example is a rotor operating in a very uneven inflow, such as the rotor operating near a wall that was discussed in chapter 10. Another method, which introduces more variables into the model, is explored in the experiment entitled. Amplitude modulation contents slide 1 amplitude modulation slide 2 the envelope and no overmodulation slide 3 example for single tone modulation slide 4 measuring the modulation index slide 5 transmitted vs. The purpose of this lab is for you to gain familiarity with the concepts of amplitude. Quadrature amplitude modulation qam pam signals occupy twice the bandwidth required for the baseband transmit two pam signals using carriers of the same frequency but in. Overmodulated am signals and its requirement for coherent detection are also considered. Introduction in this experiment you will model an am generator, making a signal of the type.
Learn to perform amplitude modulation with the agilent 33220a signal generator. Yet, am continues to be used today in many communication applications. Transmitter and receiver are simple in amplitude modulation. The process of recovery of modulating signal is called demodulation. The message signal is then used to electrically vary the amplitude. 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. Its still used in radio systems to transmit audio signals although it has lesser in popularity compared to fm due to its lower signal to noise ratio. In this modulation, the signal is sampled at regular intervals and each sample is made proportional to the amplitude of the modulating signal. Amplitude modulation a continuouswave goes on continuously without any intervals and it is the baseband message signal, which contains the information. To study amplitude demodulation by linear diode detector 3. What is amplitude modulation, am electronics notes.
In this experiment, you will examine the characteristics of amplitude modulation am. This gives us something to modulate and carry the information pattern from. Because, atmospheric propagation is good for amplitude modulated signals. Amplitude modulation is a process by which the wave signal is transmitted by modulating the amplitude of the signal. To generate and demodulate an amplitude shift keyed ask signal and a binary fsk signal. Indian institute of technology kanpur ee 381 electrical. Audio oscillator, wideband true rms meter, multiplier, adder, utilities, phase shifter, tuneable lpf, quadrature utilities, noise generator, speech, headphones 0 prelaboratory reading double sideband dsb is one of the easiest modulation techniques to understand, so it is a good. To study frequency modulation and determine its modulation factor 4. Modulation is a process of translating information signal from low band frequency to high band frequency that is suits the transmission medium. Repeat the experiment for different input signal and sampling frequencies. Information signal is usually of low frequency, so it cannot travel far. Experiment 2 experiment 6 experiment dsb sc modulation. This lab introduces students to communications theory with amplitude modulation and demodulation. Bpsk, qpsk, msk frequency shift keying, fsk quadrature amplitude modulation, qam.
The purpose of this lab is for you to gain familiarity with the concepts of amplitude modulation and. To study and perform amplitude modulation 2 to study and perform frequency modulation and demodulation. Experiment 5 amplitude modulation national instruments. By the end of this experiment, the student should be able to. Set the proper amplitude and frequency of the modulating signal to get a reasonable am waveform. Here well use the example of a square law fet as illustrated in figure 9. Amplitude modulation is mostly used in the form of electronic communication. In amplitude modulation am, the baseband information signal varies the amplitude of the higherfrequency carrier. Amplitude modulated signal can be represented by the following equation. Amplitude modulation am, demodulation and their circuit. Pdf experiment 1 amplitude shift keying kothanda thiliban. With the modulating voltage adjusted to zero amplitude, increase the carrier amplitude until v o has a value of 2 v pp.
Amplitude modulation with simple am radio transmitter duration. You can publish your book online for free in a few minutes. In frequency modulation fm, the baseband information signal varies the frequency of the higherfrequency carrier and the carrier amplitude remains constant. 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.
Amplitude modulation and demodulation electrical and computer. Intro to generation of ask amplitude shift keying ask in the context of digital communications is a modulation process, which imparts to a sinusoid two or more discrete amplitude levels. Amplitude shift keying ask is a type of amplitude modulation which represents the binary data in the form of variations in the amplitude of a signal. To generate and demodulate amplitude shift keyed ask signal using matlab theory generation of ask amplitude shift keyingaskis a modulation process, which imparts to a sinusoid two or more discrete amplitude levels. The focus of this lab is to familiarize the student with the modulation and. In pam the amplitude of the individual pulses are varied according to the amplitude of the modulating signals. This experiment examines the characteristics of the amplitude modulation am process. Amplitude modulation an interactive demo which enables you to both see and hear the result of multiplying a sine wave with a cosine amplitude envelope. Inputs of the carrier and audio information signal are applied to the modulator, and the effect of changing several parameters such as signals amplitude and frequency to the.
Therefore, both fm and pm are often referred to as angle modulation. In amplitude modulation, the amplitude signal strength of the carrier wave is varied in proportion to that of the message signal being transmitted. The second is to investigate classical analog amplitude modulation and the envelope detector. 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. Jan 31, 2018 amplitude modulation with simple am radio transmitter duration. Frequency modulation fm the process of combining the message signal with the carrier signal that causes the message signal to vary the frequency of the carrier signal. Before we study in detail about pam lets know the concepts of. In amplitude modulation, the amplitude signal strength of the carrier wave is varied in proportion to that. Amplitude modulation occurs when the source level on a rotating blade varies significantly with position. A type of dsb, called binary phaseshift keying, is used for digital telemetry. Note that this is on the very low end of the recommended voltage range. There are many methods of generating am, and this experiment explores only one of them. In this experiment, the basic principle of amplitude modulation is learned through procedures carried out.
It needs a carrier signal of higher frequency for long distance destination. It may be necessary to adjust the level and frequency of both v c and v m to achieve a suitable waveform and index of modulation. An am wave may thus be dscribed, in the most general form, as a function of time. Demonstrate the modulation and demodulation process of dsbsc. Amplitude modulation can be produced in various ways.
Is the signal modulated when it transmits through a baseband communication system. The demodulation is performed by an envelope detector. The demonstration centers around a number of signals displayed in both the time domain and the frequency domain using a signal generator, an oscilloscope to view the signal. In order to obtain both sine and cosine components of amplitude modulation, we usually repeat the experiment with some sort of phase cycling. In this case the rotor blades pass through a turbulent boundary layer that extends over about onefourth of.
Experiment 5 amplitude modulation preliminary discussion in an amplitude modulation am communications system, speech and music are converted into an electrical signal using a device such as a microphone. Quadrature amplitude modulation qam pam signals occupy. Amplitude modulation this experiment examines the characteristics of the amplitude modulation am process. This form of modulation is essentially derived from two carriers that are 90 out of phase and adding information, either analogue or digital. Before we study in detail about pam lets know the concepts of modulation. The amplitude modulation receiver will be wider when compared to the fm receiver.
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