The pulse train acts as a periodic switching signal to the modulator, which when switched on allows samples of. A brief discussion about pulse code modulation and. Click the below links to download cds lab manual 1. Matlab program for pulse code modulation m file matlab.
Pam pulse amplitude modulated modulation ve demodulation. However, this conclusion leaves the possiblity that dis tortions which are insigni. Information is conveyed by modulating some parameter of the pulses with a set of discrete instantaneous samples of the messages signal. Later in this lab, students will experiment digital communication operations such as sampling. Pulse amplitude modulation pulse code modulation sampling. Pulse amplitude modulation has some applications, but it is not used by itself in data communication. Pulse amplitude demodulation peak detection is used to detect pam. In high level amplitude modulation system, modulation is done at high power of carrier and modulating signals so power amplifiers are used to boost the carrier and modulating signals before modulation. Sampling theorem determines the necessary conditions which allow us to change an analog signal to a discrete one. Pulse code modulation pcm is a method used to digitally represent sampled analog signals. Lab report introduction pulse code modulation pcm is a digital representation of an analog signal that takes samples of the amplitude of the analog signal at regular intervals. However, it is the first step in another very popular conversion method called pulse code modulation. Amplitude modulation am the process of combining the message signal with.
A form of modulation in which a pulse train is used as the carrier. Dec 07, 2016 for the love of physics walter lewin may 16, 2011 duration. Compare the values of pam and pt for the 3 different modulation indexes. Pam however is an amplitude modulated am form of a pulse carrier 2, and hence has all the advantages and. Pulse amplitude modulation faculty of engineering and. 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. 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.
This lab introduces students to communications theory with amplitude modulation and demodulation. Pdf experimental comparison of pulse amplitude modulation. Pcm is in binary form,so there will be only two possible states high and low 0 and 1. Pulse amplitude modulation pam is the simplest pulse modulation scheme. An application of this is the simulation of a communication system that uses pulse amplitude modulation pam to transmit text messages over a bandlimited channel, such as a. Application note of pampulse amplitude modulation signal. The ideal modulated signal should have a minimum euclidean distance of 2. To study pulse amplitude modulation and demodulation. The purpose of this lab is to explore digital communications with a software radio to understand how each component works together. The lab will cover, analog to digital conversion, modulation, pulse shaping, and noise analysis 1. Note that this is on the very low end of the recommended voltage range. Because of amplitude modulation wavelength, am signals can propagate longer distances. Amplitude modulation is one of the earliest radio modulation techniques. Pulse amplitude modulation using matlab with waveforms.
Pulsecode modulation pcm is a method used to digitally represent sampled analog signals. Lab report pam modulation signal electrical engineering. To study frequency modulation and determine its modulation factor 4. In amplitude and angle modulation, some characteristic of the carrier amplitude, frequency, or phase is continuously varied in. Pam is a pulse modulation system is which the signal is sampled at regular intervals. The pam modulator and demodulator circuits simple compared to other kind of modulation and. The possible number of amplitudes can be infinite, but mostly it is some power of two so that the final output signal can be digital. Cr1 is the input diode which allows capacitor c1 to charge to the peak value of the pam input pulse. To perform the amplitude modulation and demodulation using am kit. 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. In your lab write up compare this with what is expected for a modulation depth of m 1.
T1 time division multiplexing lab university of pittsburgh. To study the effect of pam for varying width of carrier pulse train. Connect ch1 of the analog scope to the pam 2 test point on the transmit mux using a push pin. In pulse amplitude modulation system the amplitude of a carrier pulse train is varied in accordance with the instantaneous level of the modulating signal. For an introduction to the basics of matlab, see appendix a.
In pam the amplitude of the individual pulses are varied according to the amplitude of the modulating signals. The frequency of the modulation signal determines the rate of the frequency change from the center frequency. Sampling theorem and pulse amplitude modulation pam. The receivers used to listen to amdsbc are perhaps the simplest receivers of. To study amplitude demodulation by linear diode detector 3. Collector modulation method is the example of high level amplitude modulation. Generating a waveform from an analog signal which looks like pulses and contains the information present in the analog waveform by 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.
The message signal must consist of integers between 0 and m1. Electromagnetic theory and transmission lines emtl notes and textbook download click the below links to download ec05214anotes1. The demodulation is performed by an envelope detector. Analog communication pulse modulation tutorialspoint. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications. Pulse amplitude modulation and demodulation objectives. Quadrature amplitude modulation qam pam signals occupy. Sampling theorem and pulse amplitude modulation pam reference stremler, communication systems, chapter 3. The pulse amplitude modulation is the simplest form of the pulse modulation. Pulse amplitude modulation pam theory of and its applications. There is a simple pulse modulation technique called pulse amplitude modulation pam which is proved to be more power efficient than the pwm and consumes constant power for individual pulses. T12 measure the peaktopeak amplitude of the am signal, with m 1, and confirm that this magnitude is as predicted, knowing the signal levels into the multiplier, and its k factor. Amplitude modulation this experiment examines the characteristics of the amplitude modulation am process. Pam pulse amplitude modulated modulation ve demodulation sample and hold flat top mode hacettepe university ee telecommunication lab.
Pulse position modulation ppm is an analog modulation scheme in which, the amplitude and the width of the pulses are kept constant, while the position of each pulse, with reference to the position of a reference pulse varies according to the instantaneous sampled value of the message signal. The pulse train acts as a periodic switching signal to the modulator, which when switched on allows samples of the modulating signal to pass through to the output. Then as the audio signal amplitude is changed to 150 mvpp, the percentage modulation dropped to around 30%. Pulse amplitude modulation pam is used extensively in telecommunications as an. For the love of physics walter lewin may 16, 2011 duration. 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. This conforms to the expectation as the maximum and minimum peak of the modulated signal waveform varies proportional to the amplitude of the modulating signal.
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. Pulse amplitude modulation circuit, definition, advantages. Pulseamplitude demodulation peak detection is used to detect pam. The original waveform amplitude is quantized with a resulting loss of information. Pulseamplitude modulation pam, is a form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses. Overmodulated am signals and its requirement for coherent detection are also considered. The amplitude of the fm signal is constant at all times and is independent of the modulation signal. The possible number of amplitudes can be infinite, but mostly it is some power of two. Pdf pulse amplitude modulation pam and discrete multitone dmt technology are. We can also get back our analog signal by demodulation.
The pulse may take any real voltage value that is proportional to the value of the original waveform. Laboratory exercise on demodulation of pam signal asee peer. This paper discusses a laboratory experiment used to supplement a. To study sampling and reconstruction of pulse amplitude modulation system. 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. Pulse amplitude modulation is a technique in which the amplitude of each pulse is controlled by the instantaneous amplitude of the modulation signal. Dutton ee3 winter 2004 1 ee3 lab 1 amplitude modulation and demodulation 1 lab notes a word about power. The amplitude modulation receiver will be wider when compared. Oct 22, 2017 pam pulse amplitude modulated modulation ve demodulation sample and hold flat top mode hacettepe university ee telecommunication lab. The sampled analog data is changed to, and then represented by binary data. The modulated signal has a minimum euclidean distance of 2. The receivers used to listen to amdsbc are perhaps the simplest receivers of any radio modulation. No information is lost, but the energy is redistributed in the frequency domain. To construct and study the pulse amplitude modulation technique.
Figure 321 includes a simplified circuit view a for this demodulator and its waveforms views b and c. Quantization, pulse code modulation, pulse time modulation. The particular form of pulse amplitude modulation is referred to as natural pam, because the tops of the pulses follow the shape of the modulating signal. The simplest form of the pam modulator is an analog switch that is turned on and off at the rf carrier pulse rate. For amplitude modulation, we use simple and low cost circuit. Pulse amplitude modulation is defined as the data transmission by altering the amplitudes power levels or voltage of every pulse in a regular time sequence of electromagnetic pulses. Pulse amplitude modulation pam is used extensively in telecommunications as an intermediate step of other techniques such as phase shift keying psk, quadrature amplitude modulation qam and pulse code modulation pcm 1. 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.
If x is a matrix with multiple rows, the function processes the columns. Pulse amplitude modulation sakshat remote triggered lab for. Pulse amplitude modulated signal and demodulated signals are observed. 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.
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