Describe fm demodulation circuit operation for the phaseshift and gatedbeam discriminators and the ratiodetector demodulator. A carrier wave, after being modulated, if the modulated level is calculated, then such an attempt is called as modulation index or modulation depth. Modulation is the process of transforming a baseband message to a form suitable for fig. It is still in use today in a variety of systems, including, of course, am broadcast radio. To study different amplitude modulation scheme to study generation and detection of am signals to study application of am double sideband suppressed carrier dsbsc modulation double sideband large carrier dsblc modulation. The purpose of this lab is for you to gain familiarity with the concepts of amplitude modulation and demodulation. Amplitude modulation and demodulation 1 introduction this week we will be taking a look at the amplitude modulation am scheme. Amplitude modulation am is a modulation technique where the amplitude of a highfrequency sine wave.
If you look at the envelopes closely youll notice that the upper envelope is the same shape as the message. To set up pulse amplitude modulator and demodulator circuits and to. Dutton ee3 winter 2004 1 ee3 lab 1 amplitude modulation and demodulation 1 lab notes a word about power. Simple working of the circuitexperimental set upalgorithm should be written. After the demodulation, the amplitude of the demodulated signal is proportional to the modulation index. In this video you will learn about amplitude modulation and demodulation using simulaink in matlab software. We are also to carry out an ask connection, with and without manchester data coding. According to the parametric acoustic array principle and selfdemodulation theory, the theoretical. Experiment 2 amplitude modulation and demodulation pdf free download. Commercial broadcast stations use this type and it is commonly known as jus t amplitude modulation. Experiment 2 amplitude modulation and demodulationpdf. 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. Double sideband dsb is one of the easiest modulation techniques to understand, so it is a good starting point for the study of modulation. Theory of lock in modulation and demodulation 1 general scheme of lock in ring the synchronous moddemod is also called lock in modulation fig.
Check pages 51 57 of tdm pulse amplitude modulation demodulation trainer st2102. In this process, the amplitude of the carrier signal is varied so that it is proportional to the instantaneous amplitude of the modulating signal. Yet, am continues to be used today in many communication applications. The second is to investigate classical analog amplitude modulation and the envelope detector. It is a modulation on a different frequency from the original signal, to transfer out of f 1 noise fig. The pulse may take any real voltage value that is proportional to the value of the original waveform. Theory of lock in modulation and demodulationpdf free.
Dsbsc modulation, the amplitude of the carrier wave is shifted proportionally to the amplitude of the modulating signal using a modulator. From basics to adaptive trelliscoded, turboequalised and spacetime coded ofdm, cdma and mccdma systems by l. It states the level of modulation that a carrier wave undergoes. It is included to create a positive envelope which allows demodulation by a simple inexpensive envelope detector. Ask modulation introductionthe aim of this laboratory is to describe the ask amplitude shift keying modulation and demodulation. Ee3 lab 1 amplitude modulation and demodulation broadcast analog television tv signals have a bandwidth of approximately 6mhz and this is achieved with a quadrature modulation.
This principle is at the heart of amplitude modulation. To avoid distortion in recovering the modulating signal with a simple demodulator, the modulation index, m, is constrained to lie in the range zero to one. Modulation is defined as the process of changing the characteristics amplitude. Amplitude modulation circuit implementation for use in a communication. Theory shows that in order to transmit a wave effectively, the length of the. Experiment 8 amplitude modulation, demodulation and signal. Amplitude modulator and demodulator circuits unimap portal. 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. To understand amplitude and phase modulation, we change to the rotating frame of reference with. Decision maker preparation generation amplitude shift keying ask in the. Amplitude modulation process in the flip pdf version. Therefore, when we receive the amplitude modulation signal, we need to restore the audio signal. Amplitude modulation, demodulation and signal reconstruction systems and signals laboratory 2017 prof. Amplitude modulation modulation telecommunications.
Modulation and demodulation 415 amplitude change of carrier 0 amplitude of normal carrier a. The computational expense of this approach depends upon the particular modulation format and demodulation algorithm being implemented. Note that this is on the very low end of the recommended voltage range. It depends on the actual modulation type whether or not the spectra become similar with respect to shapes, symmetries, and bandwidths. Analog communications lab manual bapatla engineering. Third, the am signal will be demodulated by an envelope detector and lowpass. To study and perform amplitude modulation and demodulation. Modulation and demodulation pdf on the various aspects of modulation and demodulation. Chapter amplitude modulation and demodulation, ppt, adc. In the positive half cycle of pam signal, diode conducts and current flows through r, whereas in negative half cycle, the diode is reversed biased and. When amplitude of carrier wave is changed according to information signal is called amplitude modulation.
The original waveform amplitude is quantized with a resulting loss of information. Find more similar flip pdfs like amplitude modulator and demodulator circuits unimap portal. 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. Theory of lock in modulation and demodulationpdf free download. Capacityapproaching codes demodulation line coding modem anm pom.
Fsk modulation fsk technique is to modulate the data signal to different frequencies to achieve effective transmission. Double sideband large carrier dsblc modultion for general message signal mt. An am wave may thus be dscribed, in the most general form, as a function of time as follows. This technique contrasts with angle modulation, in which either the frequency of the. New modeling and simulation platform for communications.
Bpsk, qpsk, msk frequency shift keying, fsk quadrature amplitude modulation, qam. Amplitude modulationand coherent detection standard am contains a sinusoidal component at the carrier frequency which does not convey any message information. Amplitude modulation am is similar to dsb but has the advantage of permitting a simpler demodulator, the envelope detector. For demodulation, the audio frequency and the carrier frequency must be. Amplitude modulation am is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio carrier wave. Modulation is the process of transmitting data information in coded form, over. Qam is composed of two independent pulse amplitude modulation pam baseband modulations placed on the quadrature rails. Amplitude modulation definition, types, solved examples. Describe phase demodulation circuit operation for the peak, lowpass filter, and conversion detectors. Pulse amplitude modulation pam, is a form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses. Simulation and performance study of quadrature amplitude modulation and demodulation system. Amplitude modulation is defined as a process in which the amplitude of. Ee3 prelab 1 amplitude modulation and demodulation.
Digital communications lecture 6 modulation, demodulation. Experiment 2 amplitude modulation and demodulationpdf free. Modulation factor, m 0a 0 or 0% ii when signal amplitude is equal to the carrier amplitude as shown in fig. The modulation index m is an indicator for the degree of the amplitude modulation and is sometimes indicated in percent. Experiment 1 amplitude modulation and demodulation 1 amplitude modulation and demodulation preliminary discussion in an a mplitude m odulation am communications system, speech and music are converted into an electrical signal using a device such as a microphone. It requires that the amplitude of the dc a part of at is equal to the amplitude of the ac part a. Introduction in chapters 1 and 2 you studied how to apply intelligence modulation to an rfcarrier wave.
The maximum and minimum values of the envelope of the modulated wave are represented by a max and a min respectively. The natural sampling is basically pulse amplitude modulation. This chapter describes the essential principles behind modulation and demodulation, which we introduced briefly in chapter. Pdf simulation and performance study of quadrature. To study the effect of pam for varying width of carrier pulse train. From an information theory point of view, the power in the carrier. At the receiver, the data signal will be recovered based on the different frequencies of the received signal. Basic concept of modulation the information source typically a low frequency signal referred to as the baseband signal carrier a higher frequency sinusoid example. Tdm pulse amplitude modulationdemodulation trainer st2102. This video discusses what is amplitude modulation, definition of amplitude modulation. Why modulation is used suitable for signal transmission distanceetc. Basic theory of pulse amplitude modulation techniques.
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. This means that their ratio is unity at the output of the adder, which forces m to a. We use modulation technique to alter signals in time and frequency to accomplish desired objectives. The spectral efficiency of the transmitted ask waveform is also a consideration and the m. Experiment 1 amplitude modulation and demodulation figure 2 below shows the am signal at the bottom of figure 1 but with a dotted line added to track the modulated carriers positive peaks and negative peaks. Build and test an am modulation demodulation system and study the effect of the reconstruction filter on the quality of the recovered signal.
Message signal embed into the amplitude of carrier simple am is also called. The amplitude modulation and demodulation technique involved in this project comprises of three stages. In amplitude modulation, the amplitude signal strength of the carrier wave is varied in proportion to that of the message signal, such as an audio signal. Amplitude modulation in amplitude modulation am, the amplitude of the carrier is proportional to the message signal. A type of dsb, called binary phaseshift keying, is used for digital telemetry. From experiment 3, we know that the amplitude modulation signal utilizes the amplitude of audio signal to modulate high frequency carrier signal. Let us examine the spectrum of the demodulated dsbsc signal. With the invention of oscillators, this scheme quickly supplanted the. Chapter 6 doublesideband suppressedcarrier amplitude. I double sideband suppressed carrier am modulator dsbsc. What are the four principle operations involve in am reception. The carrier frequency, fc, should be larger than the highest spectral component.
The modulated carrier signal is sent to the receiver where demodulation of the carrier occurs to. Amplitude modulator and demodulator circuits unimap portal was published by on 20150405. Simple working of the circuitexperimental set upalgorithm should be. Pass the recovered carrier phase into the demodulator model where it can be used directly as the reference phase. Amplitude modulation process was published by on 20150406. And finally the noise effect on the connection is to be examined. What is modulation 2 modulation in the modulation process, some characteristic of a highfrequency carrier signal bandpass, is changed according to the instantaneous amplitude of the information baseband signal. Frequency versus amplitude modulation l amplitude modulation am l changes the amplitude of the carrier signal according to the amplitude of the message signal. Pulse modulation jawaharlal nehru technological university. Find more similar flip pdfs like tdm pulse amplitude modulation demodulation trainer st2102 download tdm pulse amplitude modulation demodulation trainer st2102. Amplitude modulation definition, basics and waveform hd.
Amplitude modulation and demodulation objective amplitude modulation am is one of the simplest methods for modulating a sinusoidal carrier wave. Chapter 6 modulation techniques shandong university frequency versus amplitude modulation l amplitude modulation am l changes the amplitude of the carrier signal according to the amplitude of the message signal. To construct and study the pulse amplitude modulation technique. Tdm pulse amplitude modulation demodulation trainer st2102. Vestigial sideband amplitude modulation vsbam is a modulation that improves the spectral e. Apr 05, 2015 check pages 1 50 of amplitude modulator and demodulator circuits unimap portal in the flip pdf version. To investigate amplitude modulated signal in the time domain and the frequency domain.
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