Consider an analog transmission medium is available to transmit signals, but we have a digital signal which needs to be transmitted through this analog medium. Linear modulation one scheme is to simply square the received dsb signal x2 r. In both the techniques, the baseband information is converted to radio frequency signals, but in analog modulation these rf communication signals are continuous range of values, whereas in digital modulation these are prearranged discrete states. For a better quality and efficient communication, digital modulation technique. The application of the heterodyne principle to modulation is shown schematically in figure 143. Signal is defined as the useful information which is sanded by the transmitter and received by the receiver. This can be done by converting the digital signal into analog signal. Understanding modern digital modulation techniques. Modulation in mobile computing mobile computing tutorial.
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. Modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal high frequency signal, with a modulating signal that typically contains information to be transmitted. The carrier information can be defined in two forms, digital or analog. Modulation is the process of converting data into electrical signals optimized for transmission. Chapter 7 amplitude modulation techniques generation and detection chapter outline 7. The aim of analog modulation is to transfer an analog baseband or lowpass signal, for example an audio signal or tv signal. Digital modulation involves transmission of binary signals 0 and 1.
Common digital modulation techniques and pulse modulation methods. In this video, i have explained amplitude modulation by following outlines. A modem from mo dulator dem odulator can perform both operations. Performance analysis of coherent and noncoherent modulation. Chapter 6modulation techniques shandong university. Jun 17, 2018 in this video, i have explained amplitude modulation by following outlines. So, this drawback can be overcome by the digital modulation technique. As the resultant is a coded pulse train, this is called as pcm. Analogue and digital communication techniques sciencedirect. Pdf analog and digital modulation techniques assignment. Hence info is carried in the phase or frequency of the carrier. Analog modulation delas with the voice, video and regular waves of base band signals.
In addition, a simple form of am detection and a novel use of the oscilloscope for percent modulation measurements, will be observed. Digital modulation methods can be considered as digitalto analog conversion and the corresponding demodulation or detection as analog todigital conversion. Spread spectrum frequency modulation reduces emi analog devices. Modulation l frequency modulation fm l most popular analog modulation technique l amplitude of the carrier signal is kept constant constant envelope signal, the frequency of carrier is changed according to the amplitude of the modulating message signal. Analog signal, digital signal, modulation, modulation techniques.
The am and fm radios are examples of analog data over analog medium. Modulation techniques are roughly divided into four types. Pdf analog communication system pdf notes ac notes sw. Different types of modulation techniques in communication systems.
In analog modulation, analog signal sinusoidal signal is used as a carrier signal that modulates the message signal or data signal. The microcontroller is the most efficient tool for generating various pulse width modulation techniques. Analog modulation refers to the process of transferring analog low frequency baseband signal, like an audio or tv signal over a higher frequency carrier signal such as a radio frequency band. Oct 03, 2011 this is a ppt for pulse modulation for final year ej diploma. The radios are examples of analog data over analog medium. Ee4512 analog and digital communications chapter 6 the analytical signal for double sideband, large carrier amplitude modulation dsblc am is. In analog modulation sinusoidal signal is used as carrier where as in digital modulation pulse train is used as carrier. Pulseamplitude modulation pam pulsewidth modulation pwm pulseposition modulation ppm. Analog signals have continuously varying amplitudes while digital signals consist of discrete pulses. Analogtoanalog conversion, or analog modulation, is the representation of analog information by an analog signal. 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.
Analog communication pdf notes basic concepts, frequency modulation. Fm is the method of impressing data intelligence onto an alternating wave by varying the frequency of the wave. Spread spectrum frequency modulation reduces emi analog. I will discuss both method at the end of this article. Modulation is the process of converting signals from one form into other form i. Analog and digital modulation refers to how a carrier signal is modified in order to transmit information.
Analog communications 26 other modulation methods amplitude modulation the amplitude of the carrier signal is controlled by the modulating signal pitfall of am. The changes in the carrier signal are chosen from a. Here you can download the free lecture notes of analog communication system pdf notes ac notes pdf materials with multiple file links to download. Analog communication pdf notes book starts with the topics covering introduction ac, dsb modulation, ssb modulation, angle modulation concepts, angle modulation methods, noise etc.
The main difference between analog and digital modulation is that an analog modulated signal can take up any value in a possible range whereas a digitally modulated signal can only take up one of a discrete set of values. There are two types of modulation analog and digital. Home ece branch analog communication system ac pdf notes 2020 analog communication system ac pdf notes 2020 specworld september 26, 2019 ece branch, jntu world, jntuanantapur, jntuhyderabad, jntukakinada, jntua updates, jntuh updates, jntuk updates, notes, subject notes, uncategorized 2 comments 35,008 views. Bpsk, qpsk, msk frequency shift keying, fsk quadrature amplitude modulation, qam. Modulation is needed in a communication system to achieve the following basic needs 1 multiplexing 2 practicability of antennas 3 narrow banding. This chapter describes the essential principles behind. These signals, whether digital or analog, are called baseband signals. Pulse duration modulation pdm or pulse width modulation pwm. A demodulator sometimes detector or demod is a device that performs demodulation, the inverse of modulation. At the receiving end, analog signals are converted back to a digital format before. The amount of the variance of the frequency from its base frequency think carrier frequency again is called the deviation. Analog modulation, digital modulation, pulse modulation, and spread spectrum method. The changes in the carrier signal are chosen from a finite number of m alternative symbols the modulation alphabet.
Where as digital modulations are with bit streams or symbols from computing vevices as base band signals. Demodulation is the opposite process of modulation. Pulse modulation schemes aim at transferring a narrowband analog signal over an analog baseband channel as a twolevel signal by modulating a pulse wave. The reason for that may be that the channel is bandlimited, or that we are assigned a certain frequency band and frequencies outside that band is supposed to be used by others. In digital modulation, the modulation technique used is pulse code modulation pcm where the analog signal is converted into digital form of 1s and 0s. The first radio broadcasts were done using this technique. These are not modulation schemes in the conventional sense since they are not. Analog communication pulse modulation tutorialspoint. For a signal to be transmitted to a distance, without the effect of any external interferences or noise addition and without getting faded away, it has to undergo a process called as modulation.
A signal created by any device such as a microphone pickup, a transducer, a computer terminal, etc. Section ii provides a brief overview of the considered modulation schemes. The general function sinusoidal waves is shown in the figure below, in which, three parameters can be altered to get modulation they are amplitude, frequency and phase. For analog signals, there are three wellknown modulation techniques as listed. This method is divided into single carrier modulation, by which the carrier occupies the entire bandwidth i. Therefore, dm techniques have a huge demand due to their capacity for communicating superior amounts of information than am analog modulation techniques.
Modulation method an overview sciencedirect topics. Chapter 5 traditional analog modulation techniques isy. Modulation, analog modulation, digital modulation, am,fm. Frequency modulation fm is the most popular analog modulation technique used in mobile communications systems. Amplitude and phase can be modulated simultaneously and separately. Therefore, analog modulation includes am, fm and pm and these are more sensitive to noise. It improves the strength of the signal without disturbing the parameters of the original signal. Modulation techniques pwm and pulse code modulation. In pulse width modulation or pulse duration modulation, the width of the pulse carrier is varied in accordance with the sample values of message signal or modulating signal or modulating voltage. Modulation, analog modulation, digital modulation, am,fm,pm. Organization and notations the remainder of the paper is organized as follows.
In section iii, the sinr pdf, cdf and mgf is derived. Amplitude modulation, normally abbreviated am, was the first modulation technique. Digitalto analog conversion is the process of changing one of the characteristics of an analog signal based on the information in digital data. Then all designed systems are implemented successfully in an fpga hardware. In this project, we have generated ten different types of pulse width modulation techniques for inverters. Pcm systems are complicated when compared to analog modulation methods and other systems. Modulation fm, amplitude shift keying ask, phase shift keying psk, etc. Decoding also needs special equipments and they are also too complex. The scope waveform can also be recorded if a pc is available. Analog iq modulationtransceiver iq signals take on a continuous range of values as viewed in the time domain used for amfm radios, television nonhdtv, and the first cell phones newer systems typically employ digital modulation instead receiver output 2cos2. Two methods are used to generate pwm signals digital method and analog method. Pulse coded modulation pcm is a form of modulation where there is no carrier, so. Pdf implementation of analog modulation techniques using.
Just shut off the rf carrier if there is a zero to transmit, and send a fullpower carrier if there is a one, and you have an ook modulator. In fm, the amplitude of the modulating carrier is kept constant while its frequency is varied by the modulating message signal. Digital modulation methods can be considered as digitalto analog conversion, and the corresponding demodulation or detection as analog todigital conversion. Carrier modulation and demodulation types of analog modulation technique i. The government assigns a narrow bandwidth to each radio station. Baseband signal is always analog for this modulation.
Chapter 7 amplitude modulation techniquesgeneration and. These digital modulation techniques are discussed in our digital. Analog to analog conversion, or analog modulation, is the representation of analog information by an analog signal. Modulation is needed if the medium is bandpass in nature or if only a bandpass channel is available to us. Amplitude modulation qam where both the amplitude and the phase are changed at the same time. Digital modulation in communications systems an introduction. Implementation of analog modulation techniques using. Pdf on jul 1, 2017, vidyarani k r and others published implementation of analog modulation techniques using tms320c6748 and. Glavieux a, thitimajshima p 2010 near shannon limit errorcorrecting pdf.
This is of course a form of amplitude modulation am, and it is used in many lowcost devices such as garage door openers. Ee4512 analog and digital communications chapter 6 the dsbsc am coherent receiver has a bandpass filter centered at f c and with a bandwidth of twice the bandwidth of st because of the lsb and usb. This is of course a form of amplitude modulation am, and it is. The most basic modulation method is called onoff keying ook. Common digital modulation techniques and pulse modulation. Analog to analog conversion techniques myreadingroom. Jul 30, 2019 therefore, analog modulation includes am, fm and pm and these are more sensitive to noise.
Chapter 5 traditional analog modulation techniques mikael olofsson 20022007 modulation techniques are mainly used to transmit information in a given frequency band. Digital modulation dm gives more capacity of data, high information security, and accessibility of a faster system by enormous quality communication. Some pulse modulation schemes also allow the narrowband analog signal to be transferred as a digital signal i. Sep 26, 2019 home ece branch analog communication system ac pdf notes 2020 analog communication system ac pdf notes 2020 specworld september 26, 2019 ece branch, jntu world, jntuanantapur, jntuhyderabad, jntukakinada, jntua updates, jntuh updates, jntuk updates, notes, subject notes, uncategorized 2 comments 35,008 views. Analog and digital modulation techniques assignment 1 yogesh maheshwari 201202014 introduction.
If noise enters into a system, it persists and gets carried up to the end receiver. When we change anyone of these characteristics, we create a different version of that wave. Analog modulation is typically used for am, fm radio, and shortwave broadcasting. In general when we talk about a digital system, we are usually talking about digital information over an analog medium. Sep 28, 2015 analog and digital modulation refers to how a carrier signal is modified in order to transmit information. Frequency modulation the frequency of the carrier signal is proportional to the modulating. The power efficiency is the ability of a modulation technique to preserve the. This chapter discusses the different modulation techniques that are used to convert a digital signal into an analog signal that is the appropriate form to either be transmitted down a twisted cable pair or to be applied to the radio frequency rf stage where it is modulated to a frequency that can be transmitted via microwave or satellite. The modulation techniques used for discussion are amplitude and. The amplitude of the carrier signal is controlled by the modulating signal pitfall of am. 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 process of varying any of the three characteristics as the amplitude, frequency or the phase of a carrier signal is called as modulation we know that the information signal to be transmitted can be of any form such as data, music, video etc. Hapter modulation and demodulation mit opencourseware.
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