In this experiment, you will examine the characteristics of amplitude modulation am. Therefore, both fm and pm are often referred to as angle modulation. These signals were examined in the experiment entitled. To study and perform amplitude modulation 2 to study and perform frequency modulation and demodulation. Information signal is usually of low frequency, so it cannot travel far. Phase modulation, and frequency modulation are both the modulation techniques analyzed in angle modulation. The simplicity of the modulation process contrasted with the strict requirement for a synchronous local carrier at the receiver. In this video, frequency modulation and demodulation experiment is fully explained and described and is done in fm trainer kit scientech st 2203 kit where output signals are observed in. Amplitude, frequency and phase modulation can be applied directly by software to the generated signals, which gives great flexibility where complicated and precise waveforms are required.
Upon completion of the experiment, the student will. Amplitude modulation an overview sciencedirect topics. The modulation index can be used to make the frequency deviation more sensitive or less sensitive to variations in the baseband value. Generally, and in the context of this experiment, it is understood that.
A webbased virtual laboratory on a frequency modulation. In this second experiment, we will examine the most common modulation scheme in daily life, namely, the frequency modulation, or fm. While this is the simplest technique available, it is nonlinear since. For the lowfrequency signal generator, this is equivalent to setting channel a to a 2v amplitude with 30khz frequency, and setting channel b to am under destination and 50% modulation. Experiment 5 frequency modulation ryerson university. As such, it is less affected by amplitude variations and so fm is less susceptible to noise. The process and the signal were called amplitude modulation, or am for short. It is also possible to change the frequency of a signal to give frequency modulation or fm.
In the context of radio communication, near the end of the 2oth century, few modulated signals contain a significant component at carrier frequency. 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. The concepts of amplitude modulation, modulation and demodulation, along with their. In experiment 3, dsb signals were generated by the multiplication of a message signal with a carrier waveform. Difference between amplitude modulation and frequency modulation type of modulation. Slide 6 narrow band fm slide 7 bandwidth of an fm signal slide 8 demod.
As its name implies, frequency modulation fm uses a messages amplitude to vary the frequency of a carrier instead of its amplitude. Mar 05, 2019 frequency modulation fm is an important modulation scheme both because of its widespread commercial use, and because of its simplicity. Frequency modulation fm is a type of modulation where the frequency of the carrier is varied in accordance with the modulating signal. This modulation method is, therefore, referred to as fm or frequency modulation. It needs a carrier signal of higher frequency for long distance destination. Theory of frequency modulation and phase modulation. Modulation frequency an overview sciencedirect topics. Phase modulation pm is a different form of frequency modulation and the carrier is similar in appearance to a frequencymodulated carrier. In this second experiment, we will examine the most common modulation scheme in daily life, namely, the. Difference between amplitude modulation and frequency.
It is often called as am and is commonly used in transmitting a piece of information through a radio carrier wave. The goal of this experiment is to become familiar with fm modulation and demodulation. To study frequency modulation and determine its modulation factor 4. Oct 12, 2018 theory of frequency modulation and phase modulation. Types of modulation 6 flynnkatz 7810 analog modulation amplitude modulation, am frequency modulation, fm double and single sideband, dsb and ssb digital modulation phase shift keying. Since the amplitude is kept constant, fm modulation is a low noise process and provides a high quality modulation technique which is used for music and speech in hifidelity broadcasts.
Frequency modulationsimulation experiment introduction. Amplitude modulation is a process by which the wave signal is transmitted by modulating the amplitude of the signal. What is fm, frequency modulation electronics notes. To study frequency modulation and determine its modulation factor. For a 500 khz cosine carrier wamplitude 1v, a 20 khz sinusoidal message and an fm modulator with peak frequency deviation. In frequency modulation, the instantaneous frequency of the carrier wave is modified in order to transmit information. Experiment 5 frequency modulation 1 objective to understand the principles of frequency modulation and demodulation.
Frequency modulation is widely used on frequencies above 30 mhz, and it is particularly well known for its use for vhf fm broadcasting. Basic concept of modulation the information source typically a low frequency signal referred to as the baseband signal carrier a higher frequency sinusoid example. Lab manual frequency modulation experiment 8 experiment 2 phase look loop. Frequency modulation and phase locked loops october 11, 2006 frequency modulation normally, we consider a voltage wave form with a fixed frequency of the form vt v sin. As we have seen in this document, frequency modulation can be simplified to angle modulation with a simple integrator. To demonstrate the general properties of frequencymodulated fm signals. Objectives 1 learn about vco and how it can be calibrated 2 learn how to generate fm signal using vco 3 display and measures of fm spectrum equipment required. In amplitude modulation, the amplitude of the carrier wave is modified in order to transmit 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. Since the frequency change of a sinusoid in time results in alternation of phase in time, fm may also be referred to as phase modulation, or pm, as well. The block diagram of a phase locked loop pll is shown in figure 1. Modulation is a process of translating information signal from low band frequency to high band frequency that is suits the transmission medium. We aimed not only to investigate the effect of ultrasonic pollination, but also to investigate an appropriate modulation frequency of ultrasonic waves.
Frequency modulation, fm detection, demodulation, discrimination in order to use the modulation on an fm signal, it is necessary to extract the modulation, i. Shashi heres a video i recorded of our lab expert performing frequency modulation and frequency demodulation experiment. By the end of this experiment, the student should be able to. Amplitude modulation is mostly used in the form of electronic communication. Frequency modulation and phase modulation is a system in which the amplitude of the modulated carrier is kept constant, while its frequency and rate of change are varied by the modulating signal.
Request pdf a webcast virtual laboratory on a frequency modulation experiment a number of internet remote experimentation has been successfully developed for teaching and research purposes in. Frequency modulation fm is an important modulation scheme both because of its widespread commercial use, and because of its simplicity. Frenzeljr, in handbook of serial communications interfaces, 2016. Experiment 5 amplitude modulation 2007 emona instruments 53 figure 2 below shows the am signal at the bottom of figure 1 but with a dotted line added to. A webcast virtual laboratory on a frequency modulation. In frequency modulation, the amplitude of the carrier wave is kept constant but its frequency. Frequency modulation simulation experiment introduction.
While changing the amplitude of a radio signal is the most obvious method to modulate it, it is by no means the only way. Ece 4670 spring 2014 lab 5 frequency modulation, demodulation. The sound quality offered by am radio stations is poorer, having low. To demodulate a frequency modulated signal using fm detector. Bpsk, qpsk, msk frequency shift keying, fsk quadrature amplitude modulation, qam. For the lowfrequency signal generator, this is equivalent to setting channel a to a 2v amplitude with 30khz frequency, and setting. Frequency modulation, or fm, is an important method of impressing information on a carrier.
Amplitude modulation a1 49 you will see in this experiment, and in others to follow, that there is no problem in generating an am signal with a depth of modulation exceeding 100%, and without. This means that the fm demodulator is designed to look for changes in frequency instead. If the vco was tuned precisely to the frequency of the incoming carrier. Frequency modulation is widely used for fm radio broadcasting. Now carefully repeat this experiment with the highfrequency. Generating frequency modulation fm using voltage controlled oscillator vco modified from original tims manual experiment by mr. Nov 21, 2017 frequency modulation and demodulation experiment tutorial by mr. Frequency modulation and frequency demodulation experiment. A carrier wave is purely made up of constant frequency, slightly similar to a sine wave.
The factor 2 in the equation is to account for both the upper and lower sidebands left and. The predecessor to pb2 is the polarbear1 pb1 experiment, which is currently in its fourth season of. Mar, 2018 in this video, frequency modulation and demodulation experiment is fully explained and described and is done in fm trainer kit scientech st 2203 kit where output signals are observed in nb202c dso. It does not carry much information that we can relate to data or speech. Lab manual binary frequencyshift keying bfsk experiment 8 binary objectives.
Generate and demodulate binary phase shift keying shift keyed bfsk signal. Pollination experiment was conducted in a greenhouse fig. Exercise 51 generating ssb signals by the filter method 91. In analog applications, the carrier frequency is varied in direct proportion to changes in the amplitude of an input signal. In radio transmission, an advantage of frequency modulation is that it. The information bearing signal the modulating signal changes the instantaneous frequency of the carrier. This resulted in the translation of the message spectrum to the carrier frequency location.
Frequency modulation and demodulation experiment youtube. First, since fm only changes the frequency and not the amplitude of the carrier w ave, fm receivers can be built to ignore amplitude voltage changes. Angle modulation provides the improved noise performance. Frequency modulation is a form of modulation, which represents information as variations in the instantaneous frequency of a carrier wave. The frequency of a radiofrequency channel can be explained best as the frequency of a carrier wave. Frequency modulation fm is a process in which the carrier frequency is varied by the amplitude of the modulating signal i. Cme312 lab manual frequency modulation experiment 8. The mathematical representation of frequency modulation consists of a sinusoidal expression with the integral of the baseband signal added to the argument of the sine or cosine function. By setting an appropriate modulation frequency, it is possible to carry out the pollination process more efficiently, and. It is also used in telemetry, radar, seismic prospecting, and monitoring newborns for seizures via eeg, twoway radio systems, music synthesis, magnetic taperecording systems and some videotransmission systems. In amplitude modulation, it is the voltage level of the signal to be transmitted. Frequencyshift keying modulation frequencyshift keying modulation is a form of frequency modulation fm where the. Amplitude modulation definition, types, solved examples. The subject is new and all of its ramifications and prob lems are not known as yet, hence this volume of compara tively few pages is not intended as a complete exposition of the subject.
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