Demodulation channel decoding is the corresponding process at the receiver of converting the received waveform into a. Amplitude modulation this experiment examines the characteristics of the amplitude modulation am process. Yet, am continues to be used today in many communication applications. In pulseamplitude modulation pam the amplitude of the pulses are varied in accordancewith the modulating signal. 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. Pcm is in binary form,so there will be only two possible states high and low 0 and 1. 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 pulse may take any real voltage value that is proportional to the value of the original waveform. Application note of pampulse amplitude modulation signal generation for qam transmission. Pulse amplitude modulation is the basic form of pulse modulation. Tdm pulse amplitude modulationdemodulation trainer st2102.
There are many methods of generating am, and this experiment explores only one of them. Pulse amplitude modulation pam is used extensively in telecommunications as an. Amplitude modulation am is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. Pulse amplitude demodulation peak detection is used to detect pam. Lab manual ssb modulation and demodulation experiment 7 ssb modulation and demodulation objectives. Pulse width modulation pwm or pulse duration modulation pdm or pulse time modulation ptm is an analog modulating scheme in which the duration or width or time of the pulse carrier varies proportional to the instantaneous amplitude of the message signal. We will discuss these two types of detectors in this experiment. In this modulation, the signal is sampled at regular intervals and each sample is made proportional to the amplitude of the modulating signal. 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. Demonstrate the modulation and demodulation process of ssb.
A modem is an equipment that performs both modulation and demodulation. Indian institute of technology kanpur ee 381 electrical. As we mentioned before, well use dsbc modulation because of its ease in demodulation. The demodulator is composed of a lowpass filter, whose. 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. Amplitude modulation, modulators, and demodulators fall 2009 double sideband amplitude modulation am t figure 1 sinusoidal signal with a dc component in double sideband modulation the usual am a dc component is added to the signal voltage before the signal is multiplied by a carrier. Pam pulse amplitude modulation signal generation for qam transmission mp1800a s eries. The output is a series of pulses, the amplitudes of which vary in proportion to the modulating signal. Cr1 is the input diode which allows capacitor c1 to charge to the peak value of the pam input pulse. 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. Overmodulated am signals and its requirement for coherent detection are also considered. Since amplitude modulation signal utilizes audio signal to modulate carrier signal.
The particular form of pulse amplitude modulation is referred to as natural pam, because the tops of the pulses follow the. Demodulation is the process by which the original information bearing signal, i. We can also get back our analog signal by demodulation. To study sampling and reconstruction of pulse amplitude modulation system. Source called v1 generates the message to be transmitted. Pdf experimental comparison of pulse amplitude modulation. Amplitude modulation corresponds to multiplying the carrier by the shifted baseband signal. 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.
Aly elosery october 25, 2010 this lab is divided into two parts. This gives us something to modulate and carry the information pattern from. In the frequency domain, amplitude modulation corresponds to translating the baseband spectrum to a band. Pulse amplitude modulated signal and demodulated signals are observed. Laboratory manual principles of communication system lab ee226f ivth semester prepared by. Normally detector can be classified as synchronous detector and asynchronous detector. 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 pam, is a form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses. On amplitude and frequency demodulation using energy operators. University of north carolina at charlotte department of. This is shown in block diagram form in figure 2 below.
Denoting the modulating signal as mt, pulse amplitude modulation is achieved by multiplying the carrier with the mt. Here is the circuit used for modulation and its simulation. 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. Before we study in detail about pam lets know the concepts of modulation. Observe the pulse amplitude demodulated signal at fil out, which is same as the input signal.
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. Pdf pulse amplitude modulation pam and discrete multitone dmt technology are. Experiment 10 amplitude modulation and demodulation introduction in this experiment we generate and display. Pulse amplitude modulation4 pam is probably the the simplest type of modulation. The pulse amplitude modulated signal, will follow the amplitude of the original signal, as the signal traces out the path of the whole wave. Laboratory exercise on demodulation of pam signal asee peer logo. Both processes aim to achieve transfer information with the minimum distortion, minimum loss and. In true sense, pulse amplitude modulation is analog in nature but it forms the basis ofmost digital communication and modulation systems. In amplitude modulation, the amplitude signal strength of the carrier wave is varied in proportion to that of the message signal being transmitted. National college of science and technology amafel building, aguinaldo highway dasmarinas city, cavite experiment no.
Repeat the experiment for different input signal and sampling. 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. If you continue browsing the site, you agree to the use of cookies on this website. Sampling theorem and pulse amplitude modulation pam reference stremler, communication systems, chapter 3. Oct 30, 2017 amplitude modulation and demodulation. Pulse amplitude modulation pam theory of and its applications. Pulseamplitude modulation pam, is a form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses. Amplitude modulation can be produced in various ways. Each channel sharing scheme a set of basis vectors. Here well use the example of a square law fet as illustrated in figure 9.
No information is lost, but the energy is redistributed in the frequency domain. Another method, which introduces more variables into the model, is explored in the experiment entitled. Amplitude modulation and demodulation 2017 frank dorenberg n4spp v1. Recognize pulse amplitude and pulse width modulated signals, and do simple experiments. I ntroduction an amplitude modulated signal is composed of both low frequency and high frequency components. I tried to explain the circuit connections that is needed for the experiment.
The focus of this lab is to familiarize the student with the modulation and demodulation of an am signal. The width of the pulse varies in this method, but the amplitude of the signal remains. Application note of pampulse amplitude modulation signal. Amplitude modulation or am is a method to transmit signals via electromagnetic transmission.
Analog modulation and demodulation amplitude modulation pages 306309. In this video i tried to explain the experiment amplitude modulation and demodulation. Postlab questions must be answered in each experiments. There is a mapping from the set of m 2b possible blocks into a signal constellation a a 1,a. To study amplitude demodulation by linear diode detector. By the end of this experiment, the student should be able to. The wave form of am modulation is shown in figure 3. To study and perform pulse position 6 to study and perform pulse code modulation and demodulation. Figure 321 includes a simplified circuit view a for this demodulator and its waveforms views b and c. 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. The demodulation is performed by an envelope detector.
Sinusoidal amplitude modulation amplitude demodulation. The fmmodulated signal has its instantaneous frequency that varies linearly with the amplitude of the message signal. Single sideband ssb is a common analog modulation scheme for. Amplitude modulation am, demodulation and their circuit. To study and perform pulse width modulation and demodulation.
Amplitude modulation and demodulation objective amplitude modulation am is one of the simplest methods for modulating a sinusoidal carrier wave. Pulseamplitude demodulation peak detection is used to detect pam. 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. 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. 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.
Pulse amplitude modulation is a technique in which the amplitude of each pulse is controlled by the instantaneous amplitude of the modulation signal. It is a nonlinear process that generates additional frequencies, as we will see. The message signal is, for example, a function of the sound to be. 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.
Experiment 5 frequency modulation 1 objective to understand the principles of frequency modulation and demodulation. 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. Sampling theorem and pulse amplitude modulation pam. Amplitude modulation and demodulation practical experiment. Modulation is a technique to transmit information via radio carrier waveform. This paper discusses a laboratory experiment used to supplement a. Switch off the experimental kit during making connections. 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. Sampling theorem determines the necessary conditions which allow us to change an analog signal to a discrete one. Dutton ee3 winter 2004 1 ee3 lab 1 amplitude modulation and demodulation 1 lab notes a word about power. Amplitude modulated signal can be represented by the following equation. Pcm is in binary form,so there will be only two possible states high and low0 and 1. Note that this is on the very low end of the recommended voltage range.
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