Application note of pampulse amplitude modulation signal generation for qam transmission. 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. Pam pulse amplitude modulation signal generation for qam transmission mp1800a s eries. Overview of communication topics sinusoidal amplitude modulation amplitude demodulation synchronous and asynchronous double and singlesideband am modulation pulseamplitude modulation pulse code modulation frequencydivision multiplexing timedivision multiplexing narrowband frequency modulation j. The wave form of am modulation is shown in figure 3. Sinusoidal amplitude modulation amplitude demodulation. To study amplitude demodulation by linear diode detector.
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. I tried to explain the circuit connections that is needed for the experiment. Both processes aim to achieve transfer information with the minimum distortion, minimum loss and. 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 original waveform amplitude is quantized with a resulting loss of information. 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. In this video i tried to explain the experiment amplitude modulation and demodulation. We will discuss these two types of detectors in this experiment. 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. The focus of this lab is to familiarize the student with the modulation and demodulation of an am signal. Amplitude modulation this experiment examines the characteristics of the amplitude modulation am process. Pulse amplitude modulation pam is used extensively in telecommunications as an. Sampling theorem and pulse amplitude modulation pam reference stremler, communication systems, chapter 3. Recognize pulse amplitude and pulse width modulated signals, and do simple experiments. Modulation is a technique to transmit information via radio carrier waveform.
Figure 321 includes a simplified circuit view a for this demodulator and its waveforms views b and c. University of north carolina at charlotte department of. The pulse amplitude modulated signal, will follow the amplitude of the original signal, as the signal traces out the path of the whole wave. 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. Amplitude modulation corresponds to multiplying the carrier by the shifted baseband signal. Repeat the experiment for different input signal and sampling. Laboratory manual principles of communication system lab ee226f ivth semester prepared by. Demodulation is the process by which the original information bearing signal, i. Pulse amplitude modulated signal and demodulated signals are observed. Before we study in detail about pam lets know the concepts of modulation.
Amplitude modulation can be produced in various ways. By the end of this experiment, the student should be able to. Lab manual ssb modulation and demodulation experiment 7 ssb modulation and demodulation objectives. Amplitude modulation and demodulation practical experiment. 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. Aly elosery october 25, 2010 this lab is divided into two parts. Oct 30, 2017 amplitude modulation and demodulation.
Fsk frequency shift keying d1 61 conceptually, and in fact, the transmitter could consist of two oscillators on frequencies f1 and f2, with only one being connected to the output at any one time. Laboratory exercise on demodulation of pam signal asee peer logo. Source called v1 generates the message to be transmitted. In singlechannel efield sensing, the carrier we transmit is m, the sensed value is a, and the noise is n vectors. Each channel sharing scheme a set of basis vectors. A modem is an equipment that performs both modulation and demodulation. Since amplitude modulation signal utilizes audio signal to modulate carrier signal. Pdf pulse amplitude modulation pam and discrete multitone dmt technology are. In pulseamplitude modulation pam the amplitude of the pulses are varied in accordancewith the modulating signal. Pulse amplitude demodulation peak detection is used to detect pam.
In this modulation, the signal is sampled at regular intervals and each sample is made proportional to the amplitude of the modulating signal. National college of science and technology amafel building, aguinaldo highway dasmarinas city, cavite experiment no. This gives us something to modulate and carry the information pattern from. 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. On amplitude and frequency demodulation using energy operators.
The pulse may take any real voltage value that is proportional to the value of the original waveform. Pulse amplitude modulation is the basic form of pulse modulation. I ntroduction an amplitude modulated signal is composed of both low frequency and high frequency components. Indian institute of technology kanpur ee 381 electrical. Observe the pulse amplitude demodulated signal at fil out, which is same as the input signal. Demodulation channel decoding is the corresponding process at the receiver of converting the received waveform into a. Another method, which introduces more variables into the model, is explored in the experiment entitled. The fmmodulated signal has its instantaneous frequency that varies linearly with the amplitude of the message signal. To study sampling and reconstruction of pulse amplitude modulation system. Pulse amplitude modulation4 pam is probably the the simplest type of modulation.
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. Here well use the example of a square law fet as illustrated in figure 9. The width of the pulse varies in this method, but the amplitude of the signal remains. 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. Here is the circuit used for modulation and its simulation. Denoting the modulating signal as mt, pulse amplitude modulation is achieved by multiplying the carrier with the mt. The message signal is, for example, a function of the sound to be. 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. Amplitude modulation am, demodulation and their circuit. The demodulator is composed of a lowpass filter, whose. The demodulation is performed by an envelope detector. Application note of pampulse amplitude modulation signal. Normally detector can be classified as synchronous detector and asynchronous detector. Cr1 is the input diode which allows capacitor c1 to charge to the peak value of the pam input pulse.
In true sense, pulse amplitude modulation is analog in nature but it forms the basis ofmost digital communication and modulation systems. Pcm is in binary form,so there will be only two possible states high and low0 and 1. Sampling theorem and pulse amplitude modulation pam. The modulation index can be used to make the carrier amplitude more or less sensitive to the variations in the value of the baseband signal. To study and perform pulse width modulation and demodulation. Sinusoidal amplitude modulation amplitude demodulation synchronous and asynchronous double and singlesideband am modulation pulseamplitude modulation pulse code modulation frequencydivision multiplexing timedivision multiplexing narrowband frequency modulation.
Switch off the experimental kit during making connections. Pulse code modulation is a method that is used to convert an analog signal into a digital signal, so that modified analog signal can be transmitted through the digital communication network. Experiment 5 frequency modulation 1 objective to understand the principles of frequency modulation and demodulation. Amplitude modulation and demodulation objective amplitude modulation am is one of the simplest methods for modulating a sinusoidal carrier wave. Pulse amplitude modulation is a technique in which the amplitude of each pulse is controlled by the instantaneous amplitude of the modulation signal. Analog modulation and demodulation amplitude modulation pages 306309. Single sideband ssb is a common analog modulation scheme for. Postlab questions must be answered in each experiments.
To study and perform pulse position 6 to study and perform pulse code modulation and demodulation. Pulse amplitude modulation pam theory of and its applications. Amplitude modulated signal can be represented by the following equation. In amplitude modulation, the amplitude signal strength of the carrier wave is varied in proportion to that of the message signal being transmitted. Sampling theorem determines the necessary conditions which allow us to change an analog signal to a discrete one. Ee4512 analog and digital communications chapter 6 the analytical signal for double sideband, large carrier amplitude modulation dsblc am is. If you continue browsing the site, you agree to the use of cookies on this website.
What we do in am, very roughly,is to throw away the frequency content of. To study sampling and reconstruction of pulse amplitude modulation system 6. Amplitude modulation and demodulation 2017 frank dorenberg n4spp v1. Pulseamplitude demodulation peak detection is used to detect pam. Experiment 10 amplitude modulation and demodulation introduction in this experiment we generate and display. In amplitude modulation am, we utilize the amplitude of the audio signal to modulate the amplitude of carrier signal, which means that the amplitude of carrier signal will be varied with the amplitude of the audio signal. In the frequency domain, amplitude modulation corresponds to translating the baseband spectrum to a band. As we mentioned before, well use dsbc modulation because of its ease in demodulation. No information is lost, but the energy is redistributed in the frequency domain. There are many methods of generating am, and this experiment explores only one of them. Demonstrate the modulation and demodulation process of ssb.
This is shown in block diagram form in figure 2 below. This paper discusses a laboratory experiment used to supplement a. Amplitude modulation am is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. Oct 03, 2011 this is a ppt for pulse modulation for final year ej diploma slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Yet, am continues to be used today in many communication applications. Pcm is in binary form,so there will be only two possible states high and low 0 and 1. We can also get back our analog signal by demodulation. It is a nonlinear process that generates additional frequencies, as we will see. The particular form of pulse amplitude modulation is referred to as natural pam, because the tops of the pulses follow the.
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