Marvels of modern technology in this age are increasing by the day. There are many di erent ways one can put information in it. Nptel provides elearning through online web and video courses various streams. The spectrum of an fm signal is quite complicated and is dependent on mf. Rc audio generator, oscilloscope, and spectrum analyzer demonstrations with speech and radio. As it turns out, in the digital context, phase modulation is easier to compute than frequency modulation. The carrier amplitude is constant and the phase variation of the signal contains the information. A collective class of signaling techniques are employed before transmitting a signal to provide a secure communication, known as the spread spectrum modulation. Click here to visit our frequently asked questions about html5 video.
As a result the term angle modulation is often use to describe both. Fourier transform methods are an ideal means for understanding the workings of these kinds of communication systems. Frequency modulation fm angle modulation fm and pm spectral characteristics of fm signals fm modulator and demodulator lin dai city university of hong kong ee3008 principles of communications lecture 4. As the name implies, phase modulation, pm uses variations in phase for carrying the modulation.
Pulsewidth modulation pwm at low switching frequency 3 lectures. Typically the frequency of the carrier is one or more orders of magnitude greater than the frequency of the signal it is carrying. Demonstration with professor sandy hill from the university of massachusetts at amherst. Bpsk, qpsk, msk frequency shift keying, fsk quadrature amplitude modulation, qam. Lecture 36 noise in phase and frequency modulation systems.
Communication theory frequency modulation exam study. The modulation index or modulation depth is often denoted in percentage called as percentage of modulation. Communication theory frequency modulation exam study material. 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. An important feature of angle modulation is that it can provide better. Frequency modulation fm tutorial in digital and analog modulation tutorial basics duration. Here, we consider two representative schemes, namely, phase modulation and frequency modulation. Questions from video lectures of nptel sl no questions video number time in minutes 1 give some examples for the communication systems which use space as the channel. Lecture 32 spectrum of frequency modulated fm signals. While changing the amplitude of a radio signal is the most obvious method to modulate it, it is by no means the only way.
This video will help you to understand the expression of phase modulation, use of phase modulation, working of phase modulation. This strategy enables the video signal to be transmitted more efficiently through long distances. Jun 22, 2009 lecture series on communication engineering by prof. The main advantage of spread spectrum communication technique is to prevent interference whether it is intentional or unintentional.
What is fm, frequency modulation electronics notes. It is also possible to change the frequency of a signal to give frequency modulation or fm. Today we are going to study amplitude modulation, what are its uses and limitations. Phase and frequency modulation and theirrelationship, frequency. Sep 01, 2018 phase modulation is a modulation pattern for conditioning communication signals for transmission. In this lecture we will cover continuoustime modulation. Gate preparation, nptel video lecture dvd, electronicsandcommunicationengineering, communicationtheory, frequency modulation, amplitude modulation, am wave, am. Video modulation is a strategy of transmitting video signal in the field of radio modulation and television technology.
We are all at least vaguely familiar with frequency modulationits the origin of the term fm radio. Nptel video lectures, iit video lectures online, nptel youtube lectures, free video lectures, nptel online courses, youtube iit videos nptel courses. Download ac unit 4 ac notes analog communication pdf free download unit v angle modulation methods. This is accomplished by heterodyning the intelligence frequency with the carrier frequency. A variety of techniques and circuits have been developed for. Shouribrata chatterjee, department of electrical engineering, iit delhi. Lecture series on communication engineering by prof. Am demodulation amplitude modulation refers to any method of modulating an electromagnetic carrier frequency by varying its amplitude in accordance with the message intelligence that is to be transmitted. In the early 1980s, when the dx7 was designed, microprocessors avaialble at the time didnt have enough horsepower to compute true frequency modulation in real time, but they could do phase modulation. Nagaraju associate professor r v college of engineering bangalore. May 30, 2018 frequency modulation fm tutorial in digital and analog modulation tutorial basics duration. Aug 03, 2019 angle modulation nptel pdf understanding frequency modulation fm, frequency shift keying fsk, sundes any modulation method that changes the angle instead of the amplitude is. Farshad lahouti january 20, 2003 winter 2003 uw, ece 318 lecture notes 2 information source signal modulator propagation channel signal demodulator information destination analog communication system analog signals may be transmitted directly via carrier modulat ion over. Wireless communication nptel online videos, courses iit video lectures.
We will get the percentage of modulation, just by multiplying the modulation index value with 100. Surendra prasad, department of electrical engineering,iit delhi. Rf integrated circuits online course video lectures by iit. Pdf analog communication system pdf notes ac notes sw. The aim of the exercise is to demonstrate the process of frequency modulation on the basis of the available test circuit, illustrating in detail the attributes, which are. Two important cases of angle modulation are frequency. Introduction to timefrequency analysis and wavelet transforms. If we think of frequency as something that has an instantaneous value, rather than as. But phase modulation seems to be in a different categorypm radio is by no means a common term. Nptel syllabus pulse width modulation for power electronic converters video course course outline converter topologies for acdc and dcac power conversion, overview of applications of voltage source converters. Jagannatham of iit kanpur explains the following concepts in principles of communication systemsi 1.
Phase modulation is similar to frequency modulation and is an important technique in digital communication systems. In general, video modulation means that a higher frequency carrier wave is modified according to the original video signal. Frequency modulation is widely used on frequencies above 30 mhz, and it is particularly well known for its use for vhf fm broadcasting. If not smartphones, you at least have a device at your place you can pick up and call a person who may be situated in any part of the world.
There are two common forms of angle modulation, namely, phase modulation and frequency modulation. In telecommunications and signal processing, frequency modulation fm is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave in analog frequency modulation, such as fm radio broadcasting of an audio signal representing voice or music, the instantaneous frequency deviation, the difference between the frequency of the carrier and its center. Example commercial fm signals use a peak frequency deviation of. Principles of communication systems i course swayam. For a perfect modulation, the value of modulation index should be 1, which implies the percentage of modulation should be 100%. Frequency and phase modulation sharlene katz james flynn overview history why fm.
Angle modulation nptel indian institute of technology madras. We will discuss communication applications, such as frequency division multiplexing and singleside band modulation. Gate preparation, nptel video lecture dvd, electronicsandcommunicationengineering, communicationtheory, frequencymodulation, amplitude modulation, am wave, am. This video discusses basics of frequency modulation which includes definition of frequency modulation and also frequency modulated waveform. However if st is sinusoidal, then the instantaneous frequency deviation of the anglemodulated signal is. From 2, the instantaneous frequency is obtained as f it f c. 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. The bandwidth of a monochrome video signal is about 4. Frequency modulation definition, basics and waveform hd. It encodes a message signal as variations in the instantaneous phase of a carrier wave. Bikash kumar dey department of electrical engineering iit bombay, powai mumbai 400 076, india subject expert. As phase and frequency are interrelated, this relationship carries forwards into phase modulation where it has many commonalities with frequency modulation. Though less intuitive than amplitude modulation, frequency modulation is still a fairly straightforward method of wireless data transmission. Decode each frequency bin separately channel frequency response f f timedomain signal frequency domain signal ofdm uses multiple carriers to modulate the data n carriers b modulation technique a user utilizes all carriers to transmit its data as coded quantity at each frequency carrier, which can be quadratureamplitude modulated qam.
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