Ssb sc modulation, and demodulation techniques for analog commu nication. For some applications, a small amount of carrier is kept. Osa swept optical ssbsc modulation technique for high. In am modulation the carrier signal changes almost linearly according to the modulating signal mt am modulating has different schemes doublesideband full carrier dsbfc also called the ordinary am modulation am doublesideband suppressed carrier dsbsc singlesideband ssb. Vsb modulation with envelope detection is used to modulate image in analog tv signals. As with dsbsc, the modulating signal spectrum is shifted directly to the carrier frequency band without loss. In am modulation the carrier signal changes almost. Demodulation of a modulated amplitude synthesizes the upper and lower sidebands, and produces an output signal.
In this video, i have explained ssbsc single sideband suppressed carrier by following outlines. I know this question has been asked a lot of times before but i cannot really understand how is the message transmitted in single sideband modulation. Aug 11, 2019 the power which was being utilized in a carrier and one sideband is reduced hence the more power will be consumed by only one sideband and the greater distance can be achieved by ssb modulation. In radio communications, singlesideband modulation ssb or singlesideband suppressedcarrier modulation ssb sc is a type of modulation used to transmit information, such as an audio signal, by radio waves. In ssb modulation bandwidth saving is accompanied by a. Modulation and demodulation in communication engineering. A doublesideband, suppressed carrier am signal is obtained by multiplying the message signal mt with the carrier signal. It is type of modulation used to transmit information suppressing one of the sidebands along with the carrier and transmits the information from a single sideband is called as single sideband suppressed carrier system or simply ssbsc. As we know, the transmission bandwidth of standard am as well as dsbsc modulated wave is 2w hz i.
Slide 1 singlesideband modulation slide 2 ssb by dsbscam and filtering slide 3 ssb by dsbscam and filtering cont. Department of electronics and communication engineering. Single sideband modulation, ssb demodulation electronics notes. Ssb sc modulation can be achieved with various systems, but in terms of hardware, usb or lsb can be used as a filter.
In this video, i have explained coherent detection of ssbsc or ssbsc demodulation by following outlines. Experiment 2 experiment 6 experiment dsb sc modulation. In my internet searching, i found the ssb information available on the net to be either badly. Analog communication ssbsc modulation in the previous chapters, we have discussed dsbsc modulation and demodulation. Wenzhu huang, wentao zhang, and fang li, swept optical ssb sc modulation technique for highresolution largedynamicrange static strain measurement using fbgfp sensors, opt. In order to transmit 2 channel stereo signals, dsb signals are used in. In order to demodulate single sideband, ssb, it is necessary to reintroduce the carrier. Wilkinson, uct am ssb eee3086f signals and systems ii 508 page 3 april 14, 2014 5. A refinement of amplitude modulation, it uses transmitter power and. Apr 12, 2015 modulation and demodulation in communication engineering 1. Vestigial sideband vsb modulation is a modulation technique which allows transmission of one sideband in addition with a part or vestige of the other.
An outline of dsbscssbsc modulation and demodulation. The webs wikipedia singlesideband modulation gives the mathematical details of ssb generation 1. To carry out ssb amplitude modulation, you must first compute the hilbert transform of the signal. Single sideband modulation is often compared to am, of which it is a derivative. As with dsb sc, the modulating signal spectrum is shifted directly to the carrier frequency band without loss. Dsbsc modulation at a carrier frequency, kc, specified by the student. 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. The student will learn the basic concepts of ssb modulation and using the theoretical knowledge of courses. Modulation and demodulation in communication engineering 1. External processing for controlled envelope single sideband pdf. Am modulation in order to transfer signals we need to transfer the. By the end of this experiment, the student should be able to.
Single sideband modulation via the hilbert transform. Sc modulation, and demodulation techniques for analog communication. During the transmission of binary data, dsbsc system is used in phase shift keying methods. Ssbsc modulated signal has the same bandwidth as the rf signal. Jun 24, 2018 in this video, i have explained ssb sc single sideband suppressed carrier by following outlines. The modulated signal at carrier frequency of fc can be constructed by. A refinement of amplitude modulation, it uses transmitter power and bandwidth more efficiently. For dsb sc the reinserted carrier must be exactly on frequency and in phase or else the recovered signal will be distorted. However, in searching the internet for tutorial ssb demodulation information i was shocked at how little information was available. But ssb demodulation information at that web site was terribly sparse. In both cases the transmission bandwidth b t is occupied by the upper sideband usb and lower sideband lsb.
Pdf swept optical ssbsc modulation technique for high. This means that the use of ssb modulation is inappropriate for the transmission of such message signals owing to the practical difficulty of building a filter to isolate one sideband completely. Demonstrate the modulation and demodulation process of dsbsc. The optical coherent detection is used to demodulate the optical signal to the electrical domain.
This difficulty suggests another scheme known as vestigial sideband modulation vsb, which is a compromise between ssb and dsb sc forms of modulation. Slide 7 another derivation of the ssb representation slide 8 transforms in generating ssb signal slide 9 coherent ssb demodulation slide 10 coherent demodulation cont. The following article gives an overview of the different methods for ssb demodulation and their use in software defined radios. Single sideband ssb modulation is an efficient form of amplitude modulation am that uses half the bandwidth used by am. 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. The modulated signal s dsbsc amt looks similar to st but has a temporal but not spectral carrier component. In order to transmit 2 channel stereo signals, dsb signals are used in television and fm broadcasting. And the lower sideband ssb modulation uses the lowpass. Ssb amplitude modulation reduces the bandwidth of the signal by half. Double sideband dsb is one of the easiest modulation techniques to understand, so it is a good starting point for the study of modulation. Chapter 7 singlesideband modulation and frequency translation. In this form of ssb modulation one sideband is present along with a small amount of the carrier. Ssbsc demodulation basics, block diagram and working in.
Cme312 lab manual dsbsc modulation and demodulation experiment 6 experiment 2 dsb objectives. This principle is at the heart of amplitude modulation. Chapter 7 singlesideband modulation ssb and frequency. Jun 24, 2018 in this video, i have explained coherent detection of ssb sc or ssb sc demodulation by following outlines. Coherent detection of ssb sc or ssb sc demodulation 2. Double sideband suppressed carrier dsbsc modulation. Amplitude modulation am is similar to dsb but has the advantage of permitting a simpler demodulator, the envelope detector. This points to a shortcoming of amplitude modulation, that only a fraction of the total. Doublesideband suppressed carrier modulation dsb sc 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.
Here, the same carrier signal which is used for generating ssbsc. Modulation and demo dulation 66c h a p t e r learning objectives what is a carrier wave. Vsb signals are generated using standard am or dsbsc modulation, then passing modulated signal through a sideband shaping. In this visualization we the only report we would like from the student is. See the following images taken from the book eletronic communication systems by kennedy. Understanding the phasing method of single sideband. A type of dsb, called binary phaseshift keying, is used for digital telemetry. Upon completion of the experiment, the student will.
Slide11 demodulator using a hilbert transform slide12. 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. This is what i done with matlab coding for modulation and demodulation. Ssb sc even though the modulation is different to dsb sc, i. But, at the same time, the advantage of using dsbsc instead of ssbsc is the ease of generating its signal. Am modulation in am modulation the carrier signal changes almost linearly according to the modulating signal mt am modulating has different schemes doublesideband suppressed carrier dsbsc doublesideband full carrier dsbfc also called the ordinary am modulation am singlesideband ssb. This difficulty suggests another scheme known as vestigial sideband modulation vsb, which is a compromise between ssb and dsbsc forms of modulation. Ssbsc modulation can be achieved with various systems, but in terms of hardware, usb or lsb can be used as a filter. Single sideband suppressed carrier ssbsc modulation. Swept optical ssbsc modulation technique for highresolution. Vestigial sideband vsb modulation is used to overcome this difficulty. The double sideband suppressed carrier dsbsc and single sideband suppressed carrier ssbsc are used to save power and bandwidth 1112. Hence, any of the coherent demodulation techniques applicable for dsbsc signals can be used.
Baseline parameter values are given and the modulation and demodulation technique is given mathematically. 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. Lab manual ssb modulation and demodulation experiment 7 part ll. Remember, neither yt, nor the oscillator signal, appears at the multiplier output. In brief am, of course, is both sidebands, each of which occupies the same bandwidth as the original modulating signal, and includes a full carrier. Apr 17, 2016 the main difference between demodulating ssb sc and dsb sc at least for audio signals is that for ssb the phase of the reinserted carrier doesnt matter and the frequency can even be off by a few hz.
Lab 5 amplitude modulation and demodulation prelab 5. Introduction to double sideband suppressed carrier dsbsc. The modulator the modulator outputs two files, the first with the modulated signal exactly n real elements long and the. At 100% modulation, you still have fully twothirds of the total power going into the carrier. It is an expensive technique when it comes to demodulation of the signal.
In commercial tv transmission in india, picture and speech signals are. The process of extracting an original message signal from ssbsc wave is known as detection or demodulation of ssbsc. Dec 10, 2015 single sideband suppressed carrier ssbsc modulation. Analog communication ssbsc modulation tutorialspoint.
Here, the same carrier signal which is used for generating ssbsc wave is used to detect the message signal. 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. Dec 03, 2015 double sideband suppressed carrier dsb sc system definition and mathematical expression. Single sideband am ssb is there anyway to reduce the bandwidth in ordinary am. Single sideband modulation ssb standard am and dsb sc 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. What is double sideband suppressed carrier modulation dsbsc.
The demodulation of singlesideband ssb signals requires special attention, because simple mixing leads to superposition of the upper and lower sidebands at audio frequencies. The ssbsc has the practical difficulty of isolating one sideband while transmitting the information signal. To generate amdouble side band suppressed carrier dsbsc signal. Single sideband modulation or ssb is derived from amplitude modulation am and ssb modulation overcomes a number of the disadvantages of am. During the transmission of binary data, dsb sc system is used in phase shift keying methods. This example shows how to use the discrete hilbert transform to implement single sideband modulation. Ssb modulation and demodulation pdf slide 9 coherent ssb demodulation. 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 carrier wave power relation in an am. Demodulation uses either standard am or dsbsc demodulation, depending on whether a carrier tone is transmitted. What is the difference between am, dsb sc, ssb modulation. Sc modulation, and demodulation techniques for analog commu nication. Single sideband ssb is a common analog modulation scheme for voice communications. Slide 4 ssb and hilbert transforms slide 5 ssb and hilbert transforms cont. In radio communications, singlesideband modulation ssb or singlesideband suppressedcarrier modulation ssbsc is a type.
Because ssb signals occupy a less bandwidth, the amount of noise in the information signal is also reduced. This technique is most popular in applications such as telephony, ham radio, and hf communications, i. Pdf this letter presents a static strain demodulation technique for fbgfp sensors using a suppressed carrier linbo3 ln optical single sideband. From this equation, it is obvious that the carrier component in am wave remains constant in amplitude and frequency. And if its reliable lowcost linear demodulator is used, the recovery of the modulating signal is also better than in case of ssb for being synchronous and having a frequency lock range of the suppressed carrier. Construct the block diagram of figure 3, which models the ssb regeneration block diagram, by using tims as shown in figure 6. Ssbsc single sideband suppressed carrier basics, advantages. This example shows how to implement ssb modulation using a hilbert transformer. Chapter 7 singlesidebandmodulationssb andfrequency. Ssb can be transmitted using a dsbsc modulator with a narrower bandpass filter. A narrowlinewidth tunable laser source is generated by driving the modulator using a linear chirp signal. Demonstrate the modulation and demodulation process of ssb.
It is basically a compromise between dsbsc and ssb modulation. Wilkinson, uct am ssb eee3086f signals and systems ii 508 page 4 april 14, 2014 single sideband modulation ssb dsb sc lc requires an rf bandwidth of twice the audio bandwidth. This may be used to provide a reference signal for accurate demodulation. In this experiment, the properties and characteristics of amplitude modulated am signals and their frequency spectra are examined. 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. Coherent detector is used for demodulating ssbsc wave. Doublesideband suppressedcarrier transmission wikipedia. 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. As far as demodulation is concerned, we can coherently demodulate ssb as we did the. Upper sideband ssb modulation is created with the ideal highpass filter. It represent ssb signal option d represents the conventional am signal.
Understanding single sideband modulation and demodulation. Analog communication ssbsc modulation in analog communication. 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. Then, amplitude modulate the signal using a sine with the same carrier frequency. Double sideband modulation dsb and single sideband modulation ssb. Single sideband modulation via the hilbert transform matlab. A frequency error results in a demodulated signal which has all its spectral com ponents shifted by. Doublesideband suppressedcarrier transmission dsb sc 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. 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. It is basically a compromise between dsb sc and ssb modulation. Therefore, both these systems are bandwidth inefficient systems. Because demodulation depends on the carrier being present. This letter presents a static strain demodulation technique for fbgfp sensors using a suppressed carrier linbo3 ln optical single sideband ssbsc modulator.