One of the easiest ways to implement qam with hardware is to generate and mix two sine waves that are 90 degrees out of phase with one another. Amplitude modulation and demodulation objective amplitude modulation am is one of the simplest methods for modulating a sinusoidal carrier wave. The ad633 ic is a fourquadrant analog multiplier with differential x and y inputs, and a high impedance summing input z. Lab 5 amplitude modulation and demodulation prelab 5. Analog communication laboratory manual santhosh thottingal. Amplitude modulation is mostly used in the form of electronic communication. Vf1 and other novice vfo internal voltage regulation for improved stability. There are no amplitude scales shown, but you should be able to deduce the depth.
Using amplitude modulation to shift the baseband signal fm radio 88mhz108 mhz. The two common forms of analog modulation are amplitude modulation. 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 the voltage dac vdac provides offset to the message signal mt.
Quadrature amplitude modulation qam requires changing the phase and amplitude of a carrier sine wave. Amplitude modulation definition, types, solved examples. I want to simulate amplitude modulation and at first that student understand the operation of ad633. Amplitude modulation am 9 t15 use speech or music from trunks as the message, and show that this also generates a trapezoid, and that setting the message amplitude so that the depth of modulation reaches unity on peaks a triangle is especially easy. Residual amplitude modulation in laser electrooptic phase modulation article pdf available in journal of the optical society of america b 28. How to make free energy generator 220v with 3kw alternator and 1 hp motor recycle free electricity. Amplitude modulation am the process of combining the message signal with the. Situated at the heart of these dynamic methods, a demodulator is employed to estimate amplitude and phase of the cantilever deflection signal. Qam quadrature amplitude modulation or qam is a form of modulation which is widely used for modulating data signals onto a carrier used for radio communications. Essentially an amplitude modulated wave consists of a radio frequency carrier a sine wave at one frequency, typically in the radio frequency portion of the spectrum.
Modulation is necessary in all of the above scenarios. Multiple choice questions and answers on amplitude modulation. In this experiment, the properties and characteristics of amplitude modulated am signals and their frequency spectra are examined. The idea is simple, though the notion that it can be used to modulate signals for transmission was hardly obvious before its discovery. As illustrated in figure 5, the amplifier is biased class c and the output rf signal amplitude is modulated by causing the collector supply voltage to vary with the modulation voltage. It is often called as am and is commonly used in transmitting a piece of information through a radio carrier wave.
Amplitude modulation is a process by which the wave signal is transmitted by modulating the amplitude of the signal. Analog communication pdf notes book starts with the topics covering introduction ac, dsb modulation, ssb modulation, angle modulation concepts, angle modulation methods, noise etc. Angle modulation the process of combining the message signal with the carrier signal that causes the message signal to vary the frequency andor phase of the carrier signal. 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. Ad633 application notes datasheet, cross reference, circuit and application notes in pdf format. Pdf communication engineering analog and digital laboratory.
Among the types of modulation techniques, the main classification is continuouswave modulation and pulse modulation. Collector modulation method is high level amplitude modulation c. Phase modulation is another type of angle modulation very similar to frequency modulation. Some phase modulation and quadrature amplitude modulation formats have a higher spectral efficiency for data transmission than frequency shift keying, a form of frequency modulation. The ad633 can be used as a linear amplitude modulator with no external components. Pdf analog communication system pdf notes ac notes sw. Quadrature amplitude modulation qam national instruments. Both modulated carriers are summed to result in a signal with amplitude and phase modulation. Basic concept of modulation the information source typically a low frequency signal referred to as the baseband signal carrier a higher frequency sinusoid example.
Angle modulation changes the phase of a signal as well as its amplitude, where amplitude modulation leaves the phase unchanged. The carrier and modulation inputs to the ad633 are multiplied to produce a double sideband signal. Principles of communication modulation a signal can be anything like a sound wave which comes out when you shout. The schematic is in the examples section of the ad633 datasheet.
The left and right channels each limited to 15khz are multiplexed into a single baseband signal using amplitude modulation using frequency modulation to shift the baseband. 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. Amplitude modulator using ic with simplest circuit youtube. Here you can download the free lecture notes of analog communication system pdf notes ac notes pdf materials with multiple file links to download. Quadrature amplitude modulation qam is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. Introduction what is communication transmitter channel receiver a communication system process of conveying message or information transmitter modifies the message signal into a form which is suitable for transmission over channel which is achieved by modulation information source. The ad633 is a functionally complete, fourquadrant, analog multiplier. It conveys two analog message signals, or two digital bit streams, by changing modulating the amplitudes of two carrier waves, using the amplitude shift keying ask digital modulation. It is widely used because it offers advantages over other forms of data modulation such as psk, although many forms of data modulation operate along side each other. A continuouswave goes on continuously without any intervals and it is the baseband message signal, which contains the information.
Balanced modulator an amplitude modulator that can be adjusted to control the amount of modulation. Lab1 am modulation demod handout detector radio modulation. In commercial tv transmission in india, picture and speech signals are. Amplitude modulation a continuouswave goes on continuously without any intervals and it is the baseband message signal, which contains the information. The low impedance output voltage is a nominal 10 v full scale. An am modulator is constructed using the analog devices ad534 four quadrant multiplier, and the properties of the resulting. Amplitude modulation is defined as a process in which the amplitude of the carrier wave ct. This shout can be heard only up to a certain distance. Modulation is done at high power of carrier and modulating signal b. Ad633 is a functionally complete, fourquadrant, analog multiplier.
Overmodulated am signals and its requirement for coherent detection are also considered. A simple example of generating am modulated rf with an ad633 analog multiplier chip. Am modulation and demodulation cypress semiconductor. Amplitude modulator using ic with simplest circuit. The ad633 is a functionally complete, fourquadrant, analogue multiplier. Amplitude modulation early radio ee 442 spring semester. The concluding part will be spent looking at the more popular form of high level modulation known as collector modulation or heising, named after its inventor. Pdf residual amplitude modulation in laser electrooptic. Ad633 ad633jnad633an ad633 10k resistor rn8 amplitude modulation using ad633 dc to 500 mhz rmstodc converter ad633jn ad633j ad633arreel7 ad633arreel ad633ar ad633an ad633a. Each radio station is assigned 200 khz, to transmit a stereo audio. The components of each carrier are called inphase and quadrature. Amplitude modulation this experiment examines the characteristics of the amplitude modulation am process.
The basic theory and equations behind amplitude modulation are relatively straightforward and can be handled using straightforward trigonometric calculations and manipulation. The carrier signal is fed forward to the z input of the ad633 where it is summed with the double. It includes high impedance, differential x and y inputs and a high impedance summing input z. Modulation demodulation, phase detection voltagecontrolled amplifiersattenuatorsfilters product description the ad633 is a functionally complete, fourquadrant, analog multiplier. Lab1 am modulation demod handout free download as pdf file. Power amplifiers are used to boost the carrier and modulating signals before modulation d. Amplitude modulator circuit with ad633 the ad633 can be used as a linear amplitude modulator with no external components. It includes high impedance, differential x and y inputs, and a high impedance. Principles of communication modulation tutorialspoint. Frequency modulation is a type of angle modulation. The continuous wave modulation techniques are further divided into amplitude modulation and angle modulation. The demodulation is performed by an envelope detector. Dsbfc and dsbsc am modulation with the ic ad633 youspice.