Pulse modulation demodulation of pam signals method 1. Principles of communication modulation tutorialspoint. To understand the theoretical foundations of analog communications as well as of doublesideband amplitude modulation and demodulation dsbam to design the simulink model of the dsbam to analyze each signal in time and frequency domains using time scope and spectrum analyzer. Pulse amplitude modulation is the basic form of pulse modulation in which the signal is sampled at regular and each sample is made proportional to the amplitude of the modulating signal at the sampling instant. Amplitude modulation or am is a method to transmit signals via electromagnetic transmission. Pulse amplitude demodulation september 4, 20 by ashutosh bhatt the simple pulse modulation technique called pulse amplitude modulation pam proved to be more power efficient than the pwm and consumes constant power for individual pulses like ppm. Pulseamplitude modulation pam, is a form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses. The operation theory of pcm modulation pcm modulation is a kind of source coding. To study and perform pulse position 6 to study and perform pulse code modulation and demodulation. Note that this is on the very low end of the recommended voltage range. A modem is an equipment that performs both modulation and demodulation. In general, amplitude modulation definition is given as a type of modulation where the amplitude of the carrier wave is varied in some proportion with respect to the modulating data or the signal. 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.
Pulse modulation timedivision multiplex tdm timedivision multiplexing is the method of combining several sampled signals in a definite time sequence. Apr 07, 2015 pulse width modulation pwm is a modulation technique, which converts an analog signal into a digital signal for transmission. The code for amplitude modulation am with control of modulation index ma has been developed using matlab according to conventional theory. In this chapter we will discuss ways of demodulating am, cw, fm, phase, and pulse modulation. Among the types of modulation techniques, the main classification is continuouswave modulation and pulse modulation. In the positive half cycle of pam signal, diode conducts and current flows through r. This is because the theoretical output of a balanced mixer does not. The meaning of source coding is the conversion from analog. In the pulse amplitude modulation, the message signal is sampled at regular periodic or time intervals and this each sample is made proportional to the magnitude of the message signal. Width may be varied by varying the time of occurrence of leading.
The process of demodulation for signals using amplitude modulation can be achieved in a number of different techniques, each of which has its own advantage. Storage oscilloscope is desired for satisfactory observation of pcm wave forms 4. User manual for pulse amplitude modulation and demodulation. Modulation and demodulation pdf modulation and demodulation ch16 modulator demodulation 16. This is part one of a twopart article on the basics of modulation and demodulation.
In pwm, the samples of the message signal are used to vary the duration of the individual pulses. Pdf differentialtime and pulseamplitude modulation signaling. The following safety and common symbols may be used in this manual and on the equipment. Click download or read online button to get frequency modulation book now. The pulse may take any real voltage value that is proportional to the value of the original waveform. Figure 321 includes a simplified circuit view a for this demodulator and its waveforms views b and c. The demodulation is performed by an envelope detector. In this pulse position modulation system, the amplitude and width of pulses is kept constant, while the position of each pulse, in relation to the position of a recurrent reference pulse, is varied by each instantaneous sampled value of the modulating wave. Matlab code for amplitude modulation am file exchange. Pulse position modulation ppm a pulse of fixed width and amplitude is used to transmit the information. Pulse amplitude modulation pulse amplitude modulation is a technique in which the amplitude of each pulse is controlled by the instantaneous amplitude of the modulation signal. Pulse amplitude modulation pam the actual amplitude of the pulse represents the number being transmitted.
Ee4512 analog and digital communications chapter 6 chapter 6 analog modulation and demodulation amplitude modulation pages 306309. Explain generation and demodulation of pam, ppm and pwm with waveforms. Analog pulse modulation pam pwm ppm digital pulse modulation pcm dm adm 3. To study amplitude demodulation by linear diode detector 3. Laboratory manual principles of communication system lab ee226f ivth semester. Cr1 is the input diode which allows capacitor c1 to charge to the peak value of the pam input pulse. Hence, pam is continuous in amplitude but discrete in time. Pulseamplitude modulation pam, is a form of signal modulation where the message. Explain generation and demodulation of pam, ppm and pwm with. This chapter describes the essential principles behind modulation and demodulation, which we introduced briefly in chapter. Pulse code modulation pcm is a method used to digitally represent sampled analog signals. 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.
Amplitude modulation am, demodulation and their circuit. Amplitude modulation and demodulation objective amplitude modulation am is one of the simplest methods for modulating a sinusoidal carrier wave. Modulation is the process of influencing data information on the carrier, while demodulation is the recovery of original information at the distant end from the carrier. The number of possible pulse amplitudes can be infinite in the case of analog pam, but it is usually some power of two so that the. 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. Learn about the most straightforward way of encoding information in a carrier waveform. Fig2 shows the spectrum of pulse amplitude modulated signal along with the message signal and the sampling signal which is the carrier train of pulses with the help of the waveform plotted in time domain. The continuous wave modulation techniques are further divided into amplitude modulation and angle modulation. Pam pulse amplitude modulation signal generation for qam transmission mp1800a s eries. If you want to experiment with other sounds, try the following files. Explain generation and demodulation of pam, ppm and pwm. Pulse amplitude modulation pam is the transmission of data by varying the amplitude s voltage or power levels of the individual pulses in a regularly timed sequence of electrical or electromagnetic pulses.
Qam is composed of two independent pulse amplitude modulation pam baseband modulations placed on the quadrature rails. Pulse amplitude modulation pam theory of and its applications. I ntroduction an amplitude modulated signal is composed of both low frequency and high frequency components. An am wave may thus be dscribed, in the most general form, as a function of time as follows. We will add additional functions to build the am demodulator. Pulse amplitude modulation is a technique in which the amplitude of each pulse is controlled by the instantaneous amplitude of the modulation signal. Yet, am continues to be used today in many communication applications.
A continuouswave goes on continuously without any intervals and it is the baseband message signal, which contains the information. Psdcpam is proposed to user friendly to process the experiments and the trainer had all internal features like message signal, carrier signal, power supply etc. We have seen that rf modulation is simply the intentional modification of the amplitude, frequency, or phase of a sinusoidal carrier signal. Amplitude modulation qam 4 ee4900ee6720 digital communications suketu naik quadratureamplitude modulation qam applications qam rhymes with guam and vietnam is commonly. To study frequency modulation and determine its modulation factor 4. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications. Use your project files from the previous fir laboratory. Pulse modulation and demodulation sampling theory using. University of north carolina at charlotte department of.
The goal of this experiment is to become familiar with fm modulation and demodulation. Tdm pulse amplitude modulationdemodulation trainer st2102. No information is lost, but the energy is redistributed in the frequency domain. This shout can be heard only up to a certain distance. Dtsdemodulation circuit and a pamdemodulation circ uit.
Pulse modulation may be used to transmitting analog information, such as continuous speech signal or data. 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. Seeing a little of the theory and mathematics behind amplitude modulation gives a better understanding of how it. Amplitude modulation am is an analog modulation scheme where the amplitude a of. Pulse modulation and demodulation sampling theory using matlab ismaeel laith. These sample pulses can be transmitted directly using wired media or we can use a carrier signal for transmitting through wireless. In this video i tried to explain the experiment amplitude modulation and demodulation. Amplitude modulation this experiment examines the characteristics of the amplitude modulation am process. The actual number is represented by the position in time where the pulse appears in a given time slot. Principles of communication systems 20022003 8 chapter 7. Sampling theorem and pulse amplitude modulation pam. Print means choose the print command in the file menu. Some history in the mid1870s, a form of amplitude modulation, initially called undulatory currents, was the. Fm is mostly used in highfrequency radio broadcasting, and pulse modulation is known for digital.
Pdf a pulseamplitudemodulated differentialtimesignaling pamdts architecture for serial. Modulation is defined as the process by which some characteristics of a carrier. The theory and equations show that furthest extent of the sidebands from the carrier corresponds to the highest frequency of the modulating tone for the amplitude modulated signal. Pwm converts an audio signal into a sequence of pulses having constant amplitude, but the width is proportional to amplitude of an audio signal. Demodulation is the process by which the original information bearing signal, i.
Though pcm is a more general term, it is often used to describe data encoded as lpcm. Pulse amplitude demodulation theory working of circuit. The layers of a modulator channel encoder and demodulator channel decoder. The circuit in which restoration is achieved is called the detector or demodulator both of these terms are used in neets.
If we were to implement every possible combination of demodulation algorithm, carrierrecovery technique, and clock regeneration as a distinct model, the combinatorial explosion of different models would become unmanageable. Dtsdemodulation circuit and a pamdemodulation circuit. Feb 12, 2014 pulse amplitude modulation is widely used in baseband transmission of digital data, with nonbaseband applications having been largely superseded by pulsecode modulation, and, more recently, by pulse position modulation. Sampling theorem and pulse amplitude modulation pam reference stremler, communication systems, chapter 3. To study pulse amplitude modulation and demodulation. Angle modulation ch16 angle modulation digital modulation schemes ch16 angle modulation host modulation therapy detection estimation and modulation theory part i pdf sinusoidal pulse width modulation inverter arduino. 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 modulated waveform or signal which wants to demodulate is as above, this signal is provided to the demodulator circuit to recover the signal from it. The modulated carrier signal is sent to the receiver where demodulation of the carrier occurs to recover the. To perform the amplitude modulation and demodulation using am kit. The pam signal can be demodulated by means of a low pass filter which. To study and perform pulse position modulation and demodulation. This is repeated every t seconds, such that the transmitted bit rate is bits per second.
Pdf on aug 8, 2017, kanchan wagh and others published. Amplitude modulation definition, types, solved examples. Frequency modulation fm is a process in which the carrier frequency is varied by the amplitude of the modulating signal i. Linear pulsecode modulation lpcm is a specific type of pcm where the quantization levels are linearly uniform. 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.
Oct 30, 2017 amplitude modulation and demodulation. In pulseamplitude modulation pam the amplitude of the pulses are varied in accordancewith the modulating signal. Modulation and demodulation pdf on the various aspects of modulation and demodulation. Amplitude modulation and demodulation 1 lab notes a word about power. Hapter modulation and demodulation mit opencourseware. To study sampling and reconstruction of pulse amplitude modulation system 6.
Compare the values of pam and pt for the 3 different modulation indexes. Each channel sharing scheme a set of basis vectors. The term demodulator is used because the demodulation process is considered to be the opposite of modulation. Pulse amplitude modulation an overview sciencedirect topics. Pulseamplitude modulation is the simplest form of signal modulation and analog to digital conversion method where the message information is. The output of a sampling circuit with a zeroorder hold zoh is one example of a pam signal. The focus of this lab is to familiarize the student with the modulation and demodulation of an am signal. In true sense, pulse amplitude modulation is analog in nature but it forms the basis ofmost digital communication and modulation systems.
Pulse position modulation ppm is a form of signal modulation in which m message bits are encoded by transmitting a single pulse in one of possible required time shifts. Principles of communication modulation a signal can be anything like a sound wave which comes out when you shout. Demodulation is extracting the original informationbearing signal from a carrier wave. In singlechannel efield sensing, the carrier we transmit is m, the sensed value is a, and the noise is n vectors.
It is a modulation system in which the signal is sampled at regular intervals and each sample is made proportional to the amplitude of the signal at the instant of sampling. For the baseband digital transmission, pulse amplitude modulation pam is the most. Commutator determines the synchronization and sequence of the channels signals to be sampled. In this code, it is considered the default value of ma equal to 1 for hundred percent modulation. It requires that the amplitude of the dc a part of a t is equal to the amplitude of the ac part a. A form of modulation in which a pulse train is used as the carrier. To study and perform pulse width modulation and demodulation. To study and perform pulse amplitude modulation and demodulation. The demodulator is composed of a lowpass filter, whose. As for the mechanism, when amplitude modulation is used there is a variation in the amplitude. Application note of pam pulse amplitude modulation signal generation for qam transmission. 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.
This modification is performed according to a specific scheme that is. This site is like a library, use search box in the widget to get ebook that you want. The pulse amplitude modulated signal, will follow the amplitude of the original signal, as the signal traces out the path of the whole wave. Pulse number modulation pnm related to ppm in the sense that we are using pulses with fixed amplitude and width. Theory shows that in order to transmit a wave effectively, the length of the. Pulse amplitude modulation pam is an analog modulating scheme in which the amplitude of the pulse carrier varies proportional to the instantaneous amplitude of the message signal. The spectral efficiency of the transmitted ask waveform is also a consideration and the m. Capacityapproaching codes demodulation line coding modem anm pom. Matlab program for pulse code modulation m file matlab. A demodulator is an electronic circuit or computer program in a softwaredefined radio that is used to recover the information content from the modulated carrier wave. In amplitude and angle modulation, some characteristic of the carrier amplitude, frequency, or phase is continuously varied in accordance with the modulating information.
Application note of pampulse amplitude modulation signal. Sampling theorem determines the necessary conditions which allow us to change an analog signal to a discrete one. This is in contrast to pcm encodings where quantization levels vary as a function of amplitude as with the alaw algorithm or the. I tried to explain the circuit connections that is needed for the experiment. There are many types of modulation so there are many types of demodulators.
Pulse amplitude modulation and demodulation trainer youtube. Thus the relative value of each sample is indicated. Overmodulated am signals and its requirement for coherent detection are also considered. Introduction of matlab software, mfile programming and simulink. Pulse amplitude demodulation peak detection is used to detect pam. Pulse wave modulation can be used to transmit the analog audio signal or data with a certain rate to sample the analog signal and this rate is the transmission rate. The original waveform amplitude is quantized with a resulting loss of information. 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. Pulse position modulationppm advantages disadvantage. Pulse amplitude modulation pam 169 input binary bits to signals signals to waveform baseband passband channel waveform to signals passband to output baseband binary signal decoder passband waveform baseband waveform sequence of signals figure 6. To study and perform phase shift keying 10 modulation and demodulation. Modulation is defined as the process by which some characteristics of a carrier signal is varied in accordance with a modulating signal. Frequency modulation download ebook pdf, epub, tuebl, mobi.
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