Analog communication pdf notes book starts with the topics covering introduction ac, dsb modulation, ssb modulation, angle modulation concepts, angle modulation methods, noise etc. Optical modulation index an overview sciencedirect topics. Angle cw modulation with noise in the analysis of pm and fm systems, demodulation will be represented by yt. Noise characterization of analog to digital converters for. Digital modulation an overview sciencedirect topics. Received signal quality depends on channel noise and. Analog communications 26 other modulation methods amplitude modulation the amplitude of the carrier signal is controlled by the modulating signal pitfall of am. It is the standard form of digital audio in computers, cds, digital telephony and other digital audio applications.
For a perfect modulation, the value of modulation index should be 1, which means the modulation depth should be 100%. The idea is simple, though the notion that it can be used to modulate. Because of these relationships the pdf of the envelope is rayleigh distributed, p. Analog modulation uses mainly am amplitude and fm frequency modulations. This article explains what 1f noise is and how to reduce or eliminate it in precision measurement applications.
The changes in the carrier signal are chosen from a finite number of m alternative symbols the modulation. Deltasigma or sigmadelta, modulation is a method for encoding analog signals into digital signals as found in an analogtodigital converter adc. Understanding and eliminating 1f noise analog devices. Lecture series on communication engineering by prof. Pulse code modulation pcm was pioneered by the british engineer alec reeves in 1937. In radio communications, single sideband modulation ssb or single sideband suppressedcarrier modulation ssbsc is a type of modulation used to transmit information, such as an audio signal, by radio waves. Modulation, analog modulation, digital modulation, am,fm,pm. The first transmission of a message using pcm was in 1943 during the world war ii. Modulation, analog modulation, digital modulation, am,fm. Information, transmission, modulation and noise article pdf available in proceedings of the ieee 6912.
Because the qam signal requires a much lower carriertonoise ratio than the analog signals, the optical modulation index omi for each qam channel, m 0, is much smaller than the omi of an analog signal, m a. Where as digital modulations are with bit streams or symbols from computing vevices as base band signals. Among the types of modulation techniques, the main classification is continuouswave modulation and pulse modulation. The contribution of the noise generated by the input stage has two components. Phase modulation is used in many transmission applications, notably wifi and satellite tv. This process is experimental and the keywords may be updated as the learning algorithm improves. 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. Modern telecommunication centers on the problems involved in transmitting large volumes of information over long distances without damaging loss due to noise and interference. This noise is produced by the receiver components while functioning.
Next topic pulse code modulation pulsecode modulation pcm is used to digitally represent sampled analog signals. Analog todigital converter analog signal mt analog samples pcm digital encoded signal transmitted over a communications channel to remove the digital signal from any noise on the communications channel digital encoded signal samples of quantized mt reconstructed mt with possible quantization errors digitalto analog converter. In this video, i have explained communication system by following outlines. Noise analysis for general fm signals is fairly complex and described in. Pdf information, transmission, modulation and noise. Analog communication electronic engineering mcq questions. As the resultant is a coded pulse train, this is called as pcm. Pdf analog communication system pdf notes ac notes sw. Amplitude modulation of a signal can be written as. Modern mobile communication systems use digital modulation techniques. Amplitude modulation produces an output signal the bandwidth of. Demodulation is the opposite process of modulation. The channel introduces additive noise in message and thus message received becomes corrupted. Dsb and ssb have the same noise performance as the baseband comm system.
Bpsk, qpsk, msk frequency shift keying, fsk quadrature amplitude modulation, qam. Surendra prasad, department of electrical engineering,iit delhi. Analog modulation delas with the voice, video and regular waves of base band signals. Telecommunication, science and practice of transmitting information by electromagnetic means. Digital to analog encoding modulation techniques ask. The pdf describes a reyliegh distribution, where as pdf describes a uniform. There are two types of modulation analog and digital. A comparative study of various digital modulation techniques. The predetection part of an angle modulation receiver is the same as for amplitude modulation.
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. Here you can download the free lecture notes of analog communication system pdf notes ac notes pdf materials with multiple file links to download. Jun 16, 2018 in this video, i have explained communication system by following outlines. Digital modulation in communications systems an introduction. Noise which is present only in company with a signal.
The amplitude of the analog signal is sampled at uniform intervals and each sample is quantized to its nearest. Also, output level is not dependent on optical level, and there is no degradation of signals through the system to the point that they go away, of course. Signaltonoise ratio noise s db noise signal db db noise s noise signal l noise noise l s signal x x snr p p snr snrsnr x x p p snr r ax p r ax p. 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 am and fm radios are examples of analog data over analog medium. Lecture notes on analogue communication techniques. Modulation of analog data 2 why analogtoanalog modulation. This set of data communication and networking multiple choice questions and answers mcqs focuses on digital to analog to encoding modulation techniques amplitudeshift keying ask frequencyshift keying fsk phaseshift keying psk quadrature amplitude modulationqam. 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. Pulse coded modulation pcm is a form of modulation where there is no carrier, so. The aim of digital modulation is to transfer a digital bit stream over an analog communication channel, for example over the public switched telephone network where a bandpass filter limits the frequency range to 3003400 hz or over a limited radio frequency band. In general when we talk about a digital system, we are usually talking about digital information over an analog medium.
Digital modulation schemes have greater capacity to convey large amounts of information than analog modulation schemes. No information is lost, but the energy is redistributed in the frequency domain. The continuous wave modulation techniques are further divided into amplitude modulation and angle modulation. The components in the circuits, due to continuous functioning, may produce few types of noise. Demodulation channel decoding is the corresponding process at the receiver of converting the received waveform into a. Our adc noise modeling focuses on four main noise sources, as it is depicted in fig. This effect can be explained by the amplitude modulation of the wind turbine noise level. The pulse may take any real voltage value that is proportional to the value of the original waveform. The modulation is generally distinct at short distances from the wind turbine generator wtg and may not be audible at a greater distance. Pdf analog and digital communication pdf notes adc. Pdf analog and digital communication pdf notes adc notes. Recall that our goal is to transmit data over a commu nication link, which we achieve by mapping the. Ee4512 analog and digital communications chapter 6 the analytical signal for double sideband, large carrier amplitude modulation dsblc am is. The amplitude modulation component mt can be written as.
Jun 22, 2009 lecture series on communication engineering by prof. Basic concept of modulation the information source typically a low frequency signal referred to as the baseband signal carrier a higher frequency sinusoid example. The radios are examples of analog data over analog medium. In analog recorders the recording process has a certain granularity due to the fact that the magnetic characteristics of the tape are not completely uniform which causes an irregularity in the recorded signal that sounds like noise.
It is also used to convert high bitcount, lowfrequency digital signals into lower bitcount, higherfrequency digital signals as part of the process to convert digital signals into analog as part of a digitaltoanalog converter dac. The original waveform amplitude is quantized with a resulting loss of information. This chapter describes the essential principles behind. It is the extent of modulation denoted in percentage, and is denoted by m. Analogtodigital converter analog signal mt analog samples pcm digital encoded signal. The two common forms of analog modulation are amplitude modulation.
Noise is an unwanted signal, which interferes with the original message signal and corrupts the parameters of the message signal. This analog and digital communication notes pdf bookmaterial starts with the topics covering analog communication, digital communication, data and pulse communication, source and. The am modulation level of the rf carrier can be directly related to the power supply ripple by. Am has worse noise performance, but has simpler receiver envelope detector 33 fm has much better noise performance, at the price of the increased bandwidth. Digital modulation methods can be considered as digitaltoanalog conversion and the corresponding demodulation or detection as analogtodigital conversion. The last section will discuss the sources of upstream noise, including ingress noise, and their impact on the returnpath transmission over cable tv networks. Extraterrestrial noise, such as solar noise and cosmic noise. Atmospheric noise due to irregularities in the atmosphere.
Noise performance of pulse interval modulation systems. Lecture 35 noise in am and angle modulation systems. Phase modulation noise power audio signal noise density baseband signal these keywords were added by machine and not by the authors. In digital modulation, an analog carrier signal is modulated by a discrete signal. Frequency modulation the frequency of the carrier signal is proportional to the modulating. Noise is random signal that exists in communication systems. Pulse code modulation is the heart of technology in communications in todays. A refinement of amplitude modulation, it uses transmitter power and bandwidth more efficiently. 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. Only the modulation from the analog signals is considered for the clipping noise. A continuouswave goes on continuously without any intervals and it is the baseband message signal, which contains the. Chapter 6 analog modulation and demodulation astro temple. An advantage of digital modulation is that it can operate with much lower signaltonoise ratio than can analog modulation, as shown in figure 4.
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