Frequency modulation and demodulation with spectrum analysis. Therefore, both these systems are bandwidth inefficient systems. Single sideband modulation via the hilbert transform. Sc modulation, and demodulation techniques for analog commu nication. Chapter 7 singlesidebandmodulationssb andfrequency. He has also given the advantages and disadvantages of ssbsc modulation technique. Advantages and disadvantages of standard amplitude modulation. Doublesideband suppressed carrier modulation dsbsc in full am dsbam, the carrier wave ct is completely independent of the message signal mt, which means that the transmission of carrier wave represents a waste of power. Amplitude modulation 2 marks questions and answers 1. The generated output y is a single side band signal with a suppressed carrier. Matlab code of single sided band modulation and demodulation.
In both cases the transmission bandwidth b t is occupied by the upper sideband usb and lower sideband lsb. Single sideband ssb modulation ssb modulation is a type modulation that elements all components of one sideband from an amplitude modulated wave. Vsb signals are generated using standard am or dsbsc modulation, then passing modulated signal through a sideband shaping. Ssbsc 1 bandwidth 2fm bandwidth 2fm bandwidth fm 2 contains usb,lsb,carrier. The optical coherent detection is used to demodulate the optical signal to the electrical domain. Amplitude modulationdouble sidebandsuppressed carrier. Ssb modulation, in radio communications, singlesideband.
Analog communication ssbsc modulation tutorialspoint. Analog communication ssbsc modulation in the previous chapters, we have discussed dsbsc modulation and demodulation. Single sideband modulation or ssb is derived from amplitude modulation am and ssb modulation overcomes a number of the disadvantages of am. In order to demodulate single sideband, ssb, it is necessary to reintroduce the carrier. Modulation and demodulation in communication engineering 1. Demodulation of a modulated amplitude synthesizes the upper and lower sidebands, and produces an output signal. Modulation and demodulation in communication engineering. The student will learn the basic concepts of ssb modulation and using the theoretical knowledge of courses. Upon completion of the experiment, the student will. Linear cw modulation with noise demodulation will be represented by yt v it, synchronous detector a vt. As we know, the transmission bandwidth of standard am as well as dsbsc modulated wave is 2w hz i.
It is an expensive technique when it comes to demodulation of the signal. In the previous chapters, we have discussed dsbsc modulation and demodulation. Ssbsc generation by phase shift method in communication engineering. Radio frequency spectrum sound need for modulation radio broadcasting modulation methods of modulation amplitude modulation percent modulation upper and lower sidebands mathematical analysis of a modulated. Ssb sc even though the modulation is different to dsb sc, ill try to describe it. Doublesideband suppressedcarrier transmission dsbsc is transmission in which frequencies produced by amplitude modulation am are symmetrically spaced above and below the carrier frequency and the carrier level is reduced to the lowest practical level, ideally being completely suppressed. In radio communications, singlesideband modulation ssb or singlesideband suppressedcarrier modulation ssbsc is a type. In order to transmit 2 channel stereo signals, dsb signals are used in. During the transmission of binary data, dsbsc system is used in phase shift keying methods. Ssb can be transmitted using a dsbsc modulator with a narrower bandpass filter.
Generally an envelope detector cant be used to demodulate a dsbsc. As far as demodulation is concerned, we can coherently demodulate ssb as we did the. In this lesson, deepak has explained the demodulation technique for ssbsc modulated signal. Find powerpoint presentations and slides using the power of, find free presentations research about demodulation in ssb sc ppt.
This example shows how to use the discrete hilbert transform to implement single sideband modulation. Ssbsc demodulation basics, block diagram and working in. Coherent detector is used for demodulating ssbsc wave. Ssb vs vsb difference between ssb and vsb modulation. Here, the same carrier signal which is used for generating ssbsc wave is used to detect the message signal. Osa swept optical ssbsc modulation technique for high. The carrier signal and x have sample frequency fs hz.
Baseline parameter values are given and the modulation and demodulation technique is given mathematically. A block diagram, showing how equation 2 could be modelled with hardware, is shown in figure 2 below. Here, the same carrier signal which is used for generating ssbsc. Fmstereo transmission using ssbsc modulation by frank foti. The devices used for demodulation or detection are called demodulators or detectors. Since, the two sidebands carry the same information, there is no need to transmit both sidebands. This page on ssb modulation vs vsb modulation describes difference between ssb and vsb modulation types. Lab manual ssb modulation and demodulation experiment 7 ssb generation block diagram. In this video, i have explained ssb sc single sideband suppressed carrier by following outlines. View and download powerpoint presentations on demodulation in ssb sc ppt. Dsbsc and ssbsc amplitude modulation in am, information is contained in two. Because demodulation depends on the carrier being present. As described in previous pages, single sideband is a form of amplitude modulation where the carrier and one sideband have been suppressed or reduced in level. Because of these relationships the pdf of the envelope is rayleigh.
What is double sideband suppressed carrier modulation dsb. The process of extracting an original message signal from ssbsc wave is known as detection or demodulation of ssbsc. For dsbsc or ssb demodulation, the dsbsc or ssb signal should be applied to pins 1 and 4, and the carrier to pins 8 and 10. Wenzhu huang, wentao zhang, and fang li, swept optical ssbsc modulation technique for highresolution largedynamicrange static strain measurement. Ssb generator block diagram the wideband phase splitter consists of two complementary networks say i in phase and q quadrature. Chapter 7 singlesideband modulation ssb and frequency.
In this video, i have explained coherent detection of ssbsc or ssbsc demodulation by following outlines. Capacityapproaching codes demodulation line coding modem anm pom pam pcm pdm pwm m ofdm fdm multiplexing v t e. Sc modulation, and demodulation techniques for analog communication. Single sideband modulation ssb is an amplitude modulation scheme in which only a single sideband is transmitted through the channel.
For amplitude modulation, detectors or demodulators. In this experiment, the properties and characteristics of amplitude modulated am signals and their frequency spectra are examined. Single sideband modulation is normally used for voice transmission, but technically it can be used for many other applications where two way radio communication using analogue signals is required. Pdf this letter presents a static strain demodulation technique for fbgfp sensors using a suppressed carrier linbo3 ln optical single sideband. Demodulating a signal means to get back your original signal that was actually transmitted by any modulating techniques, or rather types. Using a pilot tone information cannot be derived by a system like the costas loop because the ssb signal is the sum. Pdf created with pdffactory pro trial version problem 9 consider the following circuit. As with dsbsc, the modulating signal spectrum is shifted directly to the carrier frequency band without loss. Doublesideband suppressedcarrier transmission wikipedia. Bandpass noise referring to the communication system diagram below, xt. Ssb vs vsb difference between ssb and vsb modulation types.
Difference in demodulation of dsbsc and ssbsc fpga groups. Disadvantages of dsbsc and ssbsc the main disadvantage of dualsideband suppressed carrier and singlesideband suppressed carrier signals is that they are harder to recover or demodulate at the receiver end. Vsb modulation with envelope detection is used to modulate image in analog tv signals. Matlab code of single sided band modulation and demodulation 1 need bpsk modulation and demodulation code in matlab 2 depsk modulation and demodulation matlab code 0. This points to a shortcoming of amplitude modulation, that only a. Communication fundamentals envelope of a bandpass signal a signals gt is a bandpass signal if its fourier transform is nonnegligible only in a band of frequencies of total extent 2w centered about fc. In the end of the processing i would like to recover x with only one of the sidebands. Ssbsc modulation can be achieved with various systems, but in terms of hardware, usb or lsb can be used as a filter. It provides link to dsbsc vs ssbsc before we start our discussion, it is recommended to understand concept of dsbsc vs ssbsc which mentions difference between dsbsc and ssbsc modulation types. Lab 5 amplitude modulation and demodulation prelab 5. In radio communications, singlesideband modulation ssb or singlesideband suppressedcarrier modulation ssbsc is a type of modulation used to transmit information, such as an audio signal, by radio waves.
Ssbsc modulated signal has the same bandwidth as the rf signal. An outline of dsbscssbsc modulation and demodulation. Pdf swept optical ssbsc modulation technique for high. Single sideband modulation ssb standard am and dsbsc techniques are wasteful of bandwidth because they both require transmission bandwidth of 2b hz, where b is the bandwidth of the baseband modulating signal mt.
A refinement of amplitude modulation, it uses transmitter power and. The bias current top in 5 is commonly provided by connecting a series resistor from this pin to the power supply. Difference in demodulation of dsbsc and ssbsc hey guys, just wanted to know if any1 could please shred sum light on wa would the differnce in. Applicable where power saving and low bandwidth is needed. Demodulation uses either standard am or dsbsc demodulation, depending on whether a carrier tone is transmitted. The symbol for amplitude modulation is a multiplier, but actual circuits use the nonlinearity of. Ssb modulation by dsbscam and filtering in singlesidebandssb modulation only the upper sideband or the lower sideband is transmitted. Single sideband amplitude modulation matlab ssbmod. Modulation and demo dulation 66c h a p t e r learning objectives what is a carrier wave. Derive the current relations for singletone am amplitude modulated wave. Can we demodulate a dsbsc signal using an envelope detector. Department of electrical and computer engineering more practical bandwidth saving amplitude modulation formats vestigial side band vsb increases almost 50% effective bandwidth used in tv same as ssb but uses a practical bandpass filter quadrature amplitude modulation qam doubles the effective bandwidth uses in limited bandwidth channel applications. Matlab code for ssb demodulation using phasing method.
717 114 556 936 538 1173 1325 1353 1299 1196 51 1325 771 838 173 73 237 1356 414 1092 1419 1036 413 503 781 115 658 1037 500 1106 1243 770 206