...Introduction Modulation is the process of encoding information from a message source in a manner suitable for transmission.It involves translating a baseband message signal to a bandpass signal at frequencies that are very high compared to the baseband frequency. Baseband signal is called modulating signal.Bandpass signal is called modulated signal. In telecommunications, modulation is the process of conveying a message signal, for example a digital bit stream or an analog audio signal, inside another signal that can be physically transmitted. Modulation of a sine waveform transforms a baseband message signal into a passband signal. A modulator is a device that performs modulation. A demodulator is a device that performs demodulation, the inverse of modultion. A modem (from modulator–demodulator) can perform both operations. Types of modulation • Analog modulation • Digital modulation Analog modulation- The aim of analog modulation is to transfer an analog baseband (or lowpass) signal, for example an audio signal or TV signal, over an analog bandpass channel at a different frequency, for example over a limited radio frequency band or a cable TV network channel. • Digital modulation The aim of digital baseband modulation methods, also known as line coding, is to transfer a digital bit stream over a baseband channel, typically a non-filtered copper wire such as a serial bus or a wired local area network. AMPLITUDE MODULATION(AM) ...
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...Modulation Techniques Modulation is the process in which a signal is entered into and transmitted by a signal carrier. There are several ways signals can be modulated and differ based on the equipment and technique utilized. Three common ways that signals are transmitted include a 56K modem, an asymmetrical digital subscriber line (ADSL), and Wireless Fidelity (Wi-Fi). Each of these methods are effective means of transmitting a digital signal, however, the 56K modem is all but phased out in favor of Wi-Fi which has evolved by way of ADSL. The 56K modem offers signal modulation at 56 Kbps over a telephone network. The maximum available speed with a 56K modem is actually 64 Kbps and requires a nearly flawless digital connection at the transmitting and receiving end which is seldom available. The signal originates from the user’s Internet Service Provider’s office (usually as a digital signal) and is then converted to an analog signal by the telephone company. It is then the job of the user’s modem to convert the analog signal from the telephone company into a digital signal. The modem accomplishes this task by reading the amplitudes of the signal as an 8-bit symbol and uses an 8 kHz clock to time the signal as it is received in order to decode the data (Lawyer, 2007). As telephone companies increased their supply of internet access the demand for faster signal transmission opened the door for ADSL. Voice transmission over an ADSL only uses about 3 kHz of the over 1...
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...Chapter 5 Traditional Analog Modulation Techniques Mikael Olofsson — 2002–2007 Modulation techniques are mainly used to transmit information in a given frequency band. The reason for that may be that the channel is band-limited, or that we are assigned a certain frequency band and frequencies outside that band is supposed to be used by others. Therefore, we are interested in the spectral properties of various modulation techniques. The modulation techniques described here have a long history in radio applications. The information to be transmitted is normally an analog so called baseband signal. By that we understand a signal with the main part of its spectrum around zero. Especially, that means that the main part of the spectrum is below some frequency W , called the bandwidth of the signal. We also consider methods to demodulate the modulated signals, i.e. to regain the original signal from the modulated one. Noise added by the channel will necessarily affect the demodulated signal. We separate the analysis of those demodulation methods into one part where we assume an ideal channel that does not add any noise, and another part where we assume that the channel adds white Gaussian noise. 5.1 Amplitude Modulation Amplitude modulation, normally abbreviated AM, was the first modulation technique. The first radio broadcasts were done using this technique. The reason for that is that AM signals can be detected very easily. Essentially, all you need is a nonlinearity. Actually...
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...Phase Modulation Phase Modulation “is used in many applications to carry both analogue and digital signals. Keeping the amplitude of the signal constant, the phase is varied to carry the required information or signal” (Poole, Radio-Electronics.com). An advantage of phase modulation is that it is easier compared to Frequency modulation. A Phase modulator is used in determining velocity of moving targets by extracting Doppler information. Doppler information needs a stable carrier which is possible in phase modulation but not in frequency modulation. A disadvantage of Phase modulation is that a frequency multiplier is needed in order to increase Phase modulation. Quadrature Amplitude Modulation Quadrature Amplitude Modulation or QAM is a form of modulation which is widely used for modulating data signals onto a carrier used for radio communications. It is widely used because it offers advantages over other forms of data modulation such as PSK, although many forms of data modulation operate alongside each other. “QAM is a signal in which two carriers shifted in phase by 90 degrees are modulated and the resultant output consists of both amplitude and phase variations. In view of the fact that both amplitude and phase variations are present; it may also be considered as a mixture of amplitude and phase modulation” (Poole, Radio-Electronics.com). There are more disadvantages with QAM then there are advantages. One disadvantage is it is more susceptible to noise because the states...
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...Advantages and disadvantages of the following analog modulation techniques: In analog technology, compare and contrast the advantages and disadvantages of amplitude modulation, frequency modulation, phase modulation, and Quadrature Amplitude Modulation Amplitude Modulation When dealing with communication modulation is the process of altering one or more of the three primary parameters of a message signal. Modulation of message signals allow for the signal to be imbedded into a carrier signal that can be physically transmitted. The three primary parameters are amplitude, frequency, and phase. When dealing with analog modulation techniques each one that is used will have advantages and disadvantages. The amplitude modulation (AM) technique is based on the transformation of the highs and lows of a signal wave or its strength. This technique has the advantages of being able to travel long distances by bouncing off of structures as well as the atmosphere. The main disadvantage of this modulation technique is that is highly susceptible to signal interference from other electronic devices and waves creating and unclear signal, these interferences are what is known has noise. Frequency modulation (FM) is that of what its names says it is the altering of the frequency of a baseband signal. Altering the number of times each second that the current changes direction; comes with the advantage of being less susceptible to noise unlike that of AM. Also unlike AM, FM is not...
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...The objective of this experiment is to learn the principles of amplitude modulation and to observe the outcome when the two signals are mixed. Basically in this experiment we were trying to explore and study about amplitude modulation. Amplitude modulation is used in electronic communication and is commonly used for transmitting information or messages by a radio carrier wave. I find this experiment very useful to us because it will further enhance our learning and will acquaint us more on what we are able to discuss in our lecture class about amplitude modulation. The experiment is very short yet we were able to learn more and were able to see an actual waveform generated which supports the lessons that we have learned from our lecture classes. I might say that so far this is the only experiment that we were able to finish it with complacency. During the first part of our experiment we were trying to get the expected waveform of a modulated signal using the ECE21 board #1 and ECE21 board #4.We tried to adjust the frequencies of the signal generator and its amplitude which is 3 Vpp to get the expected waveform. Once the waveform is obtain, we then compute the percent modulation of the circuit using the Vmax and the Vmin of the waveform obtained and displayed in our oscilloscope. We tried to decrease the amplitude of the panel generator to zero and was able to notice that it will result to a small amplitude and a non-modulated signal. We also tried to increase the amplitude...
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...Unit 3 Assignment 1: Frequency Modulation Ch. 5 (pp 253-255 1, 2, 6, 7, 8, 12, 14, 16, 17, 20, 26, 28, 33, 35, 48 Section 5-1 1. Define angle modulation and list its subcategories. Answer: Angle modulation is defined as modulation where the angle of a sine-wave carrier is varied from its reference value. The subcategories are Phase modulation and Frequency modulation. 2. What is the difference between frequency and phase modulation? Answer: The difference between frequency and phase modulation is; Frequency modulation is where the instantaneous frequency of a carrier is caused to vary by an amount proportional to the modulating signal amplitude, Phase modulation is the same but it is where the phase angle of a carrier is caused to depart from its reference value. Section 5-2 6. Define deviation constant. Answer: Deviation Constant is defined as in units of kHz/V. and it’s how much the carrier frequency will deviate for a given modulating input voltage level. 7. A 50-mV sinusoid, at a frequency of 1 kHz, is applied to a capacitor microphone FM generator. If the deviation constant for the capacitor microphone FM generator is 500 Hz/20 mV, determine: (a) The total frequency deviation. (±1.25 kHz) Answer: 50mV x (500 Hz)/(20 mV)= ±1.25 kHz (b) The rate at which the carrier frequency is being deviated. (1 kHz) Answer: The rate at which the carrier frequency is being deviated is ±1.25 kHz at a rate of 1 kHz. 8. Explain how the intelligence signal modulates...
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...Performance Evaluation of OFDM System for Different Channel and Different Modulation Techniques Thesis Report Department of Electronic and Telecommunication Engineering (ETE) Submitted By Foysal Bin Wadud (T-093011) Gazi Shamsul Arefeen Shams (T-093016) Supervised By Engr. Mohammad Jashim Uddin Contact Information: Foysal Bin Wadud (Mamun), Dept. of ETE, International Islamic University Chittagong, Metric No.: T093011, Email: mamunmoon19@yahoo.com Contact No.: +8801717934676 Gazi Shamsul Arefeen (Shams) Dept. of ETE, International Islamic University Chittagong, Metric No.: T093016, Email: shams.ete@gmail.com Contact No.: +8801676848247 Contact Information of Supervisor: Md. Jashim Uddin Dept. Of ETE, International Islamic University Chittagong. Contact No. +8801716-823959 Email: jashimcuet@yahoo.com Abstract The demand for high-speed mobile wireless communications is rapidly growing. Orthogonal Frequency Division Multiplexing (OFDM) technology promises to be a key technique for achieving the high data capacity and spectral efficiency requirements for wireless communication systems in the near future. An Orthogonal Frequency Division Multiplexing (OFDM) scheme offers high spectral efficiency and better resistance to fading environments. In OFDM the data is modulated using multiple numbers of sub-carriers that are orthogonal to each other because of which the problems associated with other modulation schemes such as Inter Symbol Interference (ISI) and Inter Carrier Interference...
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...Review Questions for Test-2 (Partial List) Part-A End-of-Chapter-4 Questions (match questions, overlook number mismatch) 1. How does analog data differ from digital data? Computers produce digital data that are binary, either on or off. In contrast, telephones produce analog data whose electrical signals are shaped like the sound waves they transfer. Analog data are signals that vary continuously within a range of values (e.g., temperature is analog). 1. Clearly explain the differences between analog data, analog transmission, digital data, and digital transmission. Data can be transmitted through a circuit in the same form they are produced. Most computers, for example, transmit their data through digital circuits to printers and other attached devices. Likewise, analog voice data can be transmitted through telephone networks in analog form. In general, networks designed primarily to transmit digital computer data tend to use digital transmission, and networks designed primarily to transmit analog voice data tend to use analog transmission (at least for some parts of the transmission). 4. How does baseband differ from broadband? Baseband is the digital transmission of binary electrical pulses. Broadband is the analog waveform used for transmission. 4. What is coding? Coding is the representation of one set of symbols by another set of symbols. In data communications, this coding is a specific arrangement of binary 0s and 1s used to represent...
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...to the electrical charge from electrons through the flow of holes that leads to current. As in the waterfall analogy, the rate at which the water is falling is similar to the current flow in a circuit. The third important characteristic of electricity is resistance, which refers to the amount of opposition to the flow of electrons. Higher is the value of resistance in electrons flowing. According to OHMS, these three characteristics are related by the equation V=I* R [pic] Analogy of the OHMS law with the water flow model. Analogy vs. Digital Modulation The main aim of analog modulation is to transfer and analog low pass signals. For example, audio signal or television signals over an analog band pass channel, a limited radio frequency band or a cable television network channel. The main aim of digital modulation is to transfer a digital bit stream over an analog band pass channel. For example, over the public switched...
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...different languages people can speak all over the world. Without proper translation and understanding, the conversation is pointless; this analogy is similar for analog and digital transmissions. Beginning with an analog signal, which is a continuous variable along amplitude and frequency. Analog circuits need to have a defined frequency band in which it operates. Different modulation schemes can vary the speed in which they operate, the quality of wire they require, the immunity to noise, and their overall complexity. The variety of modulation schemes in existence can be a disadvantage as this means many incompatibilities can exist within a single application. Such modulations include: * Amplitude modulation (AM) - modem relies on amplitude and associates high amplitude/zeros with low amplitude. Amplitude modulation can be demodulated using a circuit consisting of very few components but lacks a bit of quality, much like with AM radio frequencies. * Frequency modulation (FM) - modem altars the frequency value and decodes original bit patterns based on the frequency of the received signal. Frequency modulation has the advantage that, as amplitude variations do not carry any information on the signal, it can be...
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...different times due to reflection. Multiple Choice Identify the choice that best completes the statement or answers the question. ____ 6. Which of the following is an electromagnetic wave? a. | light | c. | radio | b. | heat | d. | All of the above | ____ 7. Which of the following units is used to measure frequency? a. | decibel | c. | hertz | b. | volt | d. | byte | ____ 8. The term ____ describes the rate of electrical flow. a. | voltage | c. | resistance | b. | current | d. | electrical power | ____ 9. ____ modulation changes the number of waves representing one cycle. a. | Amplitude | c. | Frequency | b. | Phase shift | d. | Phase | ____ 10. Which type of modulation changes the starting point of the cycle to represent a change from a 1 bit to a 0 bit and vice versa? a. | AM | c. | DM | b. | FM | d. | PM | ____ 11. Which binary modulation technique is similar to frequency modulation? a. | amplitude shift keying | c. | phase shift keying | b. | frequency shift keying | d. | All of the above | ____ 12. Power of an electromagnetic signal such as one used in WLANs is measured by which unit? a. | millivolts | c. | milliohms | b. | milliamps | d. | milliwatts | ____ 13. When an RF signal moves from one medium to another of a different...
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...Chapter 1 Basic Networking Chapter 1 Basic Networking: Data communication is the transfer of data from one device to another via some form of transmission medium. A data communications system must transmit data to the correct destination in an accurate and timely manner. The five components that make up a data communications system are the message, sender, receiver, medium, and protocol. Text, numbers, images, audio, and video are different forms of information. Data flow between two devices can occur in one of three ways: simplex, halfduplex, or full-duplex. A network is a set of communication devices connected by media links. In a point-to-point connection, two and only two devices are connected by a dedicated link. In a multipoint connection, three or more devices share a link. Topology refers to the physical or logical arrangement of a network. Devices may be arranged in a mesh, star, bus, or ring topology. A network can be categorized as a local area network (LAN), a metropolitan-area network (MAN), or a wide area network (WAN). A LAN is a data communication system within a building, plant, or campus, or between nearby buildings. A MAN is a data communication system covering an area the size of a town or city. A WAN is a data communication system spanning states, countries, or the whole world. An internet is a network of networks. The Internet is a collection of many separate networks. TCP/IP is the protocol suite for the Internet...
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...photons from excited atoms or molecules. Lasers are used in drilling and cutting, alignment and guidance, and in surgery; the optical properties are exploited in holography, reading bar codes, and in recording and playing compact discs. 4. Output Pattern: aka NA of light source directly relates to the energy coupled into the core of the optical fiber. 5. Output Power: Amount of power a component, circuit or system can deliver to a load. 6. Modulation Speed: In fiber optics, modulation is associated with the telecommunications and data transport of digital information signals and analog audio/video signals, in which the digital/analog signal(s) are transmitted within another sine wave form known as a "passband". Common references for analog include pulse-code modulation (PCM), amplitude modulation (AM) and frequency modulation (FM). Digital modulation technologies are accomplished by "keying" methods: Phase-shift keying (PSK), Frequency-shift keying (FSK), Amplitude-shift keying (ASK) and Quadrature-amplitude modulation (QAM). 7. Core Diameter Mismatch: The central part of an optical fiber that provides the transmission region for an optical signal. The core is manufactured of an optically pure glass of a high refractive index surrounded by a lower refractive index cladding. Optical cores can range in size from 4.5...
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...1 CHAPTER-1 INTRODUCTION Seminar Report For Electronics (ECE) / Electrical (EEE) / Instrumentation (EI or AE&I) Engineering or Sciences 1INTRODUCTION Are you tired of slow modem connections? Cellonics Incorporated has developed new technology that may end this and other communications problems forever. The new modulation and demodulation technology is called Cellonics. In general, this technology will allow for modem speeds that are 1,000 times faster than our present modems. The development is based on the way biological cells communicate with each other and nonlinear dynamical systems (NDS). Major telcos, which are telecommunications companies, will benefit from the incredible speed, simplicity, and robustness of this new technology, as well as individual users. In current technology, the ASCII uses a combination of ones and zeros to display a single letter of the alphabet (Cellonics, 2001). Then the data is sent over radio frequency cycle to its destination where it is then decoded. The original technology also utilizes carrier signals as a reference which uses hundreds of wave cycles before a decoder can decide on the bit value (Legard, 2001), whether the bit is a one or a zero, in order to translate that into a single character. The Cellonics technology came about after studying biological cell behaviour. The study showed that human cells respond to stimuli and generate waveforms that consist of a continuous line of pulses separated by periods of silence. The...
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