In singlechannel efield sensing, the carrier we transmit is m, the sensed value is a, and the noise is n vectors. 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. Hapter modulation and demodulation mit opencourseware. It is an expensive technique when it comes to demodulation of the signal. Modulation choose the letter which answer each question. Fmstereo transmission using ssbsc modulation by frank foti.
In this video, i have explained ssbsc single sideband suppressed carrier by following outlines. What part of the poem quietness where the persona is situated. One approach to reduce this interference, known as frequencydivision multiplexing, allocates different carrier frequencies to different users or for dif. Audio oscillator, wideband true rms meter, multiplier, adder, utilities, phase shifter, tuneable lpf, quadrature utilities, noise generator, speech, headphones 0 prelaboratory reading double sideband dsb is one of the easiest modulation techniques to understand, so it is a good. Demodulation is the process of recovering the original information from a modulated carrier wave. 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. Wenzhu huang, wentao zhang, and fang li, swept optical ssbsc modulation technique for highresolution largedynamicrange static strain measurement.
Double side band suppresed carrier 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 re. Amplitude modulation am radio is a commonplace technology today, and is standard in any type of commercial stereo device. Because of the low cost of the parts necessary to implement am transmission and the simplicity of the underlying technology, using amplitude modulations is a cheap and effective way to perform many tasks that require wireless communication. Carrier modulation allows the transmission of modulating frequencies without the use of transmission wire as a medium. Pdf swept optical ssbsc modulation technique for high. The webs wikipedia singlesideband modulation gives the mathematical details of ssb generation 1. The theory of dsbscssbsc modulation and demodulation double sideband suppressed carrier modulation at the beginning of the explanation of amplitude modulation, we explained the am radio system, but the term for amplitude in the theoretical expression was complex. This points to a shortcoming of amplitude modulation, that only a. After comparing dsbsc vs ssbsc and studying the difference between dsbsc and ssbsc one can also refer following comparison between various modulation types as. From an information theory point of view, the power in the carrier component is wasted. A modem is an equipment that performs both modulation and demodulation. Single sideband ssb modulation ssb modulation is a type modulation that elements all components of one sideband from an amplitude modulated wave. Analog communication ssbsc modulation tutorialspoint. Amplitude modulation definition, types, solved examples.
Each channel sharing scheme a set of basis vectors. Single sideband amplitude demodulation matlab ssbdemod. It is often called as am and is commonly used in transmitting a piece of information through a radio carrier wave. Osa swept optical ssbsc modulation technique for high. Double sideband dsb and amplitude modulation am modules. Analog communication ssbsc modulation in analog communication analog communication ssbsc modulation in analog communication courses with reference manuals and examples pdf. If modulation is performed for a message signal with more than one frequency component then the modulation is called multi tone modulation. If modulation is performed for a message signal with one frequency component then the modulation is called single tone modulation. Ssbsc modulated signal has the same bandwidth as the rf signal. Dsbsc modulated signals undergo phase reversal when mt changes sign. The student will learn the basic concepts of ssb modulation and using the theoretical knowledge of courses. Using a pilot tone information cannot be derived by a system like the costas loop because the ssb signal is the sum. As far as demodulation is concerned, we can coherently demodulate ssb as we did the.
Introduction to modulation and demodulation modulation. Understanding single sideband modulation and demodulation. 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. Doublesideband suppressedcarrier amplitude modulation contents slide 1 doublesideband suppressedcarrier. Therefore, both these systems are bandwidth inefficient systems. This is shown in block diagram form in figure 2 below. Both processes aim to achieve transfer information with the minimum distortion, minimum loss and. In both cases the transmission bandwidth b t is occupied by the upper sideband usb and lower sideband lsb. What is double sideband suppressed carrier modulation dsb. Then, amplitude modulate the signal using a sine with the same carrier frequency. Modulation and demodulation medium, it would be dif. What you should and should not do in community immersion. Chapter 7 singlesidebandmodulationssb andfrequency. Modulation is the process of influencing data information on the carrier, while demodulation is the recovery of original information at the distant end from the carrier.
The dsbsc modulated signal consists of two sidebands that is double sided band. Hilbert transform, properties of hilbert transform, preenvelope, canonical representation of bandpass signals, single sideband modulation, frequencydomain description of ssb modulated signals, frequency discrimination method for generating an ssb modulated wave, timedomain description, phase discrimination method for generating an ssb. In order to demodulate single sideband, ssb, it is necessary to reintroduce the carrier. Single sideband modulation via the hilbert transform. If the amplitude of the carrier wave is simply changed and mathematised, it is. Ssb modulation by dsbscam and filtering in singlesidebandssb modulation only the upper sideband or the lower sideband is transmitted. Amplitude modulation is a process by which the wave signal is transmitted by modulating the amplitude of the signal. Analog communication ssbsc modulation in the previous chapters, we have discussed dsbsc modulation and demodulation. This example shows how to use the discrete hilbert transform to implement single sideband modulation.
Here, the same carrier signal which is used for generating ssbsc. Lab manual ssb modulation and demodulation experiment 7 ssb generation block diagram. The envelope detector and product detector are few of the am detectors. Demodulation and calculation of sideband power in am. As we know, the transmission bandwidth of standard am as well as dsbsc modulated wave is 2w hz i. The process of extracting an original message signal from ssbsc wave is known as detection or demodulation of ssbsc. Introduction in chapters 1 and 2 you studied how to apply intelligence modulation to an rfcarrier wave. Coherent detection of ssbsc or ssbsc demodulation 2. Data communication using dsbsc am modulation demodulation of modified square wave. Demodulation is done by multiplying the dsbsc signal with the carrier signal. The modulated signal has zero initial phase, and can be an upper or lowersideband signal. Coherent detector is used for demodulating ssbsc wave.
Ssb generator block diagram the wideband phase splitter consists of two complementary networks say i in phase and q quadrature. So if the carrier were 1 mhz and the modulation the message were 2 khz, you would see frequencies of 998 khz and 1002 khz on a spectrum analyser. This chapter describes the essential principles behind. Single sideband suppressed carrier ssbsc modulation. Chapter 6 doublesideband suppressedcarrier amplitude. A continuouswave goes on continuously without any intervals and it is the baseband message signal, which contains the information. Sc modulation, and demodulation techniques for analog commu nication. Calculate the side band power in an ssbsc signal when there is 50% modulation and the carrier power is 50w.
Upon completion of the experiment, the student will. For demodulation, the modulation oscillators frequency and phase must be exactly the same as the demodulation oscillators otherwise, distortion andor attenuation will occur. Understanding the phasing method of single sideband. An outline of dsbscssbsc modulation and demodulation. Ssb amplitude modulation reduces the bandwidth of the signal by half.
Among the types of modulation techniques, the main classification is continuouswave modulation and pulse modulation. Sc modulation, and demodulation techniques for analog communication. In this video, i have explained coherent detection of ssbsc or ssbsc demodulation by following outlines. Here, the same carrier signal which is used for generating ssbsc wave is used to detect the message signal. Describe phase demodulation circuit operation for the peak, lowpass filter, and conversion detectors. Larger modulation index reduces power but makes demodulation harder. Multiple choice questions and answers on amplitude modulation. Pdf this letter presents a static strain demodulation technique for fbgfp sensors using a suppressed carrier linbo3 ln optical single sideband. Please focus on conceptual treatment rather than individual techniques of modulation. During the transmission of binary data, dsbsc system is used in phase shift keying methods. The continuous wave modulation techniques are further divided into amplitude modulation and angle modulation. This is what i done with matlab coding for modulation and demodulation.
In the previous chapters, we have mentioned about dsbsc modulation and demodulation. To carry out ssb amplitude modulation, you must first compute the hilbert transform of the signal. The optical coherent detection is used to demodulate the optical signal to the electrical domain. Calculate the power in one of the side band in ssbsc modulation when the carrier power is 124w and there is 80% modulation depth in the amplitude modulated signal. Amplitude modulation is mostly used in the form of electronic communication. In order to transmit 2 channel stereo signals, dsb signals are used in. Dsbsc can be demodulated if modulation index is less than unity. Demodulation channel decoding is the corresponding process at the receiver of converting the received waveform into a. A sequence of spectral diagrams are shown on the next page. Parti experiment4doublesidebandsuppressed carrier dsbsc. The hilbert transform finds applications in modulators and demodulators, speech processing, medical imaging, direction of arrival doa measurements, essentially anywhere complexsignal quadrature processing simplifies the design.
A block diagram, showing how equation 2 could be modelled with hardware, is shown in figure 2 below. However, in searching the internet for tutorial ssb demodulation information i was shocked at how little information was available. 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. Ssbsc demodulation basics, block diagram and working in. Introduction to modulation and demodulation free download as powerpoint presentation.
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