The document discusses telecommunications basics, including:
1) Signals carry information through a communication channel via variations in amplitude, frequency, or other physical properties over time.
2) Analog signals can be converted to digital signals by sampling and coding, allowing more robust transmission.
3) Modulation encodes information onto carrier signals to allow multiple users to share channels. Demodulation retrieves the original information.
4) Techniques like frequency division, time division, and code division multiplexing allow channels to be shared between multiple users.
Analog signals are continuous waves that vary smoothly over time and can have an infinite number of values, while digital signals are discrete and can have only a limited set of values, such as 1 and 0. Analog signals are typically represented by sine waves, while digital signals are represented by square waves. While analog signals are best for audio and video transmission, digital signals are better suited for digital data transmission and provide benefits such as easier compression, encryption, and error detection.
This document discusses key concepts in data transmission including:
1) Data transmission involves transmitting data between a transmitter and receiver via some medium, which can be guided (e.g. cable) or unguided/wireless (e.g. air).
2) Transmission can be direct point-to-point, multi-point involving more than two devices, or simplex, half-duplex, or full-duplex depending on direction of communication.
3) Digital signals maintain constant levels that change abruptly, while analog signals vary smoothly over time. Periodic signals have a repeated pattern while aperiodic signals do not.
4) Transmission is impaired by attenuation, delay distortion, noise,
This document outlines the learning outcomes and content for a course on communication system fundamentals. The key topics covered include the basic elements of a communication system, noise and interference, signal-to-noise ratios, and modulation techniques. Specifically, it defines the five basic elements of any communication system as the information source, transmitter, transmission medium, receiver, and destination. It also explains the different types of noise including internal and external noise, and how signal-to-noise ratios are calculated.
This document provides an overview of analog and digital signals, periodic signals, digital signals, and transmission impairment. It discusses topics such as:
- Analog signals are continuous while digital signals have discrete states
- Periodic signals can be simple or composite, with a composite made of multiple sine waves
- Digital signals have a bit rate and bandwidth requirement for transmission
- Transmission is impaired by attenuation, distortion, and noise, which can be measured by signal-to-noise ratio
- Data rate limits depend on bandwidth, signal levels, and channel noise as defined by Nyquist rate and Shannon capacity.
This document discusses various types of transmission impairments including attenuation, distortion, and noise. Attenuation is the reduction of signal strength during transmission, while distortion alters the original signal shape. There are different types of distortion such as amplitude, delay, and frequency distortion. Noise refers to random electrical signals that interfere with reception, and can come from internal or external sources. Signal-to-noise ratio and noise figure are discussed as ways to measure noise levels relative to signals.
The document discusses various channel impairments that can affect communication signals as they propagate through a channel. It describes additive noise such as thermal noise generated by electronic components. It also discusses phenomena such as fading caused by multipath propagation, as well as other distortion effects like attenuation and interference that can corrupt signals. Intersymbol interference occurs when multipath causes signals to spread and overlap adjacent symbols. The document notes several types of noise and interference sources and explains how they degrade the signal-to-noise ratio.
This document provides an overview of analog communication systems and modulation techniques. It discusses the basic components of communication systems including the transmitter, transmission channel, receiver, and transducers. It then describes analog modulation methods like amplitude modulation (AM) and frequency modulation (FM) and how they vary the amplitude or frequency of a carrier wave to transmit a baseband signal. Digital modulation techniques like amplitude-shift keying (ASK) and frequency-shift keying (FSK) are also introduced. Modems are defined as devices that enable data transfer over analog networks by modulating and demodulating signals.
This presentation deals with topics such as Electromagnetic Spectrum, Wireless Propagation, Signals, Signal propagation effects, Spread spectrum and cellular systems.
Analog signals are continuous waves that vary smoothly over time and can have an infinite number of values, while digital signals are discrete and can have only a limited set of values, such as 1 and 0. Analog signals are typically represented by sine waves, while digital signals are represented by square waves. While analog signals are best for audio and video transmission, digital signals are better suited for digital data transmission and provide benefits such as easier compression, encryption, and error detection.
This document discusses key concepts in data transmission including:
1) Data transmission involves transmitting data between a transmitter and receiver via some medium, which can be guided (e.g. cable) or unguided/wireless (e.g. air).
2) Transmission can be direct point-to-point, multi-point involving more than two devices, or simplex, half-duplex, or full-duplex depending on direction of communication.
3) Digital signals maintain constant levels that change abruptly, while analog signals vary smoothly over time. Periodic signals have a repeated pattern while aperiodic signals do not.
4) Transmission is impaired by attenuation, delay distortion, noise,
This document outlines the learning outcomes and content for a course on communication system fundamentals. The key topics covered include the basic elements of a communication system, noise and interference, signal-to-noise ratios, and modulation techniques. Specifically, it defines the five basic elements of any communication system as the information source, transmitter, transmission medium, receiver, and destination. It also explains the different types of noise including internal and external noise, and how signal-to-noise ratios are calculated.
This document provides an overview of analog and digital signals, periodic signals, digital signals, and transmission impairment. It discusses topics such as:
- Analog signals are continuous while digital signals have discrete states
- Periodic signals can be simple or composite, with a composite made of multiple sine waves
- Digital signals have a bit rate and bandwidth requirement for transmission
- Transmission is impaired by attenuation, distortion, and noise, which can be measured by signal-to-noise ratio
- Data rate limits depend on bandwidth, signal levels, and channel noise as defined by Nyquist rate and Shannon capacity.
This document discusses various types of transmission impairments including attenuation, distortion, and noise. Attenuation is the reduction of signal strength during transmission, while distortion alters the original signal shape. There are different types of distortion such as amplitude, delay, and frequency distortion. Noise refers to random electrical signals that interfere with reception, and can come from internal or external sources. Signal-to-noise ratio and noise figure are discussed as ways to measure noise levels relative to signals.
The document discusses various channel impairments that can affect communication signals as they propagate through a channel. It describes additive noise such as thermal noise generated by electronic components. It also discusses phenomena such as fading caused by multipath propagation, as well as other distortion effects like attenuation and interference that can corrupt signals. Intersymbol interference occurs when multipath causes signals to spread and overlap adjacent symbols. The document notes several types of noise and interference sources and explains how they degrade the signal-to-noise ratio.
This document provides an overview of analog communication systems and modulation techniques. It discusses the basic components of communication systems including the transmitter, transmission channel, receiver, and transducers. It then describes analog modulation methods like amplitude modulation (AM) and frequency modulation (FM) and how they vary the amplitude or frequency of a carrier wave to transmit a baseband signal. Digital modulation techniques like amplitude-shift keying (ASK) and frequency-shift keying (FSK) are also introduced. Modems are defined as devices that enable data transfer over analog networks by modulating and demodulating signals.
This presentation deals with topics such as Electromagnetic Spectrum, Wireless Propagation, Signals, Signal propagation effects, Spread spectrum and cellular systems.
Effective bandwidth refers to the bandwidth of an input signal that can be transmitted without distortion through a system. If the input signal bandwidth is larger than the system bandwidth, the output will be distorted. The signal and system bandwidths should match. Transmission impairments like attenuation, delay distortion, and noise can distort signals and introduce errors. Different types of cables like twisted pair, coaxial, and optical fiber have different characteristics for digital data transmission.
The document discusses key concepts in data transmission including:
1) Transmission occurs over guided or unguided media between a transmitter and receiver.
2) Signals can be analyzed in the frequency domain and have properties like frequency, spectrum, and bandwidth.
3) Both analog and digital signals are used to represent data for transmission.
This document provides an overview of principles of communication. It discusses key components of a communication system including the transmitter, communication channel, and receiver. It describes different forms of modulation used in analog and digital communication systems, including amplitude modulation, frequency modulation, and pulse modulation. It also discusses antennas, communication channels, receivers, and applications of communication systems like data transmission, fax, radio, television, and satellite communication.
This includes Digital signal data transmission, Base band and band pass transmission. Also detailed with PAM, PPM, PWM, PCM, DPCM, DM, ADM, ASK, PSK, FSK.
This document defines and describes key concepts in electronic communication systems including transmitters, channels, receivers, signal types (analog, digital, continuous, discrete), periodic and non-periodic signals, even and odd signals, and units of measurement such as decibels and dBm. It provides examples of converting between absolute power ratios and decibels, as well as converting between milliwatts and dBm.
Analog communication System Basic Introduction by A Sravan KumarAPPALASRAVANKUMAR
This document discusses analog communication systems and key concepts related to noise. It describes the basic communication process involving a sender, receiver, and communication channel. It defines noise as any unwanted signal added to the desired message signal. Noise can reduce signal bandwidth, require increased transmitting power, and cause misunderstanding of signals. Noise is classified as either external noise from man-made, atmospheric, or extraterrestrial sources, or internal noise such as thermal, shot, time transit time, and miscellaneous noises. The document also discusses signal-to-noise ratio, defined as the ratio of signal power to noise power, and how it is expressed in decibels. Finally, it mentions noise factor, noise figure, and noise temperature as related
This document provides an overview of wireless networks and technologies. It discusses the history of wireless communication from Marconi's invention of the wireless telegraph to modern cellular networks. It also covers key topics in wireless networking including broadband wireless, antennas and propagation, transmission impairments like noise and multipath, and error compensation techniques like forward error correction and diversity. The document is an introduction to wireless concepts for students intended to provide foundational knowledge.
The document discusses digital transmission fundamentals, including:
- Digital representation of analog signals involves sampling, quantization, and pulse code modulation.
- The sampling rate must be at least twice the bandwidth of the signal to allow perfect reconstruction.
- Quantization maps samples to discrete levels, introducing quantization error. More levels reduce error but increase transmission bandwidth needs.
- Digital transmission enables long distance communication by regeneration of the digital signal rather than analog amplification, overcoming distance limitations of analog systems.
This document discusses data and signals used in data communication. It defines analog and digital data, as well as continuous and discrete signals. Signals can be transformed into electromagnetic waves for transmission. Both signals and data can be either analog or digital. The key properties of signals, including amplitude, period, frequency, phase, and wavelength are described. The document also discusses how signals can be impaired by attenuation, distortion, and noise during transmission. The Nyquist sampling theorem and Shannon capacity theorem place important limits on maximum data transmission rates based on bandwidth and signal-to-noise ratio. Examples are provided to illustrate how to calculate transmission rates, signal levels, amplification, and bandwidth.
Ripple control is a power line communication method used by electric utilities to remotely control loads like water heaters and street lights. It works by superimposing a coded control signal onto the 50Hz voltage waveform.
While smart meters allow for two-way communication, ripple control still provides utilities faster load control during emergencies compared to wireless options. Grid sensing uses sensor networks to monitor the electric grid in real-time for issues like equipment failures. Load management through ripple control involves directly or indirectly controlling loads like water heaters during peak periods to reduce demand. Attenuation can cause receiving relays not to operate loads as intended, while amplification can cause interference in customer equipment. Utilities mitigate inappropriate signal levels by
Satellite communication analog and digital signalsAjay Kumar
This document discusses various sources of information and signals used in satellite communication, their characteristics, and applications. It describes primary information sources like speech, audio, video, and data. It then covers analog signals, including different types of analog signals and modulation schemes used. The document also discusses digital signals, examples of encoding digital data, and various digital modulation schemes. It provides advantages and disadvantages of both analog and digital signals.
Digital Communication System
Communication Channels
AWGN: Universal channel model
Band Limited Channel: Channel BW <Signal BW, ISI
Fading Channel: multipath waves
Basic Modulation Methods
Criteria for choosing Modulation Schemes
Power Efficiency: Required Eb/N for certain error probability over AWGN channel
Bandwidth Efficiency: no. of bits per second that can be transmitted on system bandwidth.
System Complexity: Amount of circuit involved and complexity
System Performance Parameters
Average SNR
Outage Probability: instantaneous prob. Exceed certain limit
Average BEP
Amount of Fading/severity of fading
Average Outage duration: O/P SNR fall below certain SNR
This document discusses various methods of information transmission including digital-to-digital, analog-to-digital, transmission modes, digital-to-analog, and analog-to-analog conversion. It describes techniques such as line coding, block coding, pulse code modulation, delta modulation, asynchronous/synchronous/isochronous transmission, and analog modulation methods including amplitude, frequency, and phase modulation. The key steps and processes involved in each conversion technique are explained, along with considerations for bandwidth and how analog or digital signals are represented.
The document discusses digital communication systems and outlines topics that will be covered, including digital data communication, multiplexing techniques, digital modulation and demodulation, and performance comparisons of modulation schemes. The objectives are to provide an overview of communication systems and concepts, discuss digital transmission methods and modulation types, and enable students to design simple communication systems and discuss industry trends.
1) Noise exists in all communication systems and degrades signal quality. It is caused by random movement of electrons and can be internal or external.
2) Thermal noise, also known as Johnson noise, is generated by thermal agitation of electrons in conductors. It is proportional to temperature and bandwidth.
3) Noise figure and noise temperature are used to measure the degradation of signal to noise ratio caused by components in a communication system. Lower noise figure and temperature indicate less degradation.
The Nyquist formula states that the maximum data rate supported by a bandwidth B is 2B bits per second. Doubling the bandwidth doubles the maximum data rate. Signals with more than two levels can represent more data per signal, with the formula becoming C = 2B log2M, where M is the number of signal levels. Shannon's channel capacity theorem defines the maximum reliable transmission rate C for a bandwidth B channel as C = B log2(1 + S/N), where S is the signal power and N is the noise power.
This document provides information about Ass. Prof. Ibrar Ullah who teaches communication systems at CECos University. It includes his educational background and contact information. The rest of the document is a chapter on sampling and pulse code modulation that is divided into sections covering topics like sampling, signal interpolation, and pulse code modulation. It also includes sections on noise, noise power, noise figure, and Friis' formula for amplifier cascades.
Most electronic communication signals can be represented by sine and cosine waves. Sine and cosine waves are periodic and can be converted between each other using trigonometric identities. Fourier analysis techniques such as Fourier series and Fourier transforms are used to represent signals in the time and frequency domains.
1) O documento apresenta sinopses de vários livros, incluindo O Sol Também é uma Estrela de Nicola Yoon, A Chave de Rebecca de Ken Follett e Irmãos de Sangue de Nora Roberts.
2) É fornecido contexto sobre os autores e suas obras, como vendas, prêmios recebidos e adaptações para outros meios.
3) Informações técnicas sobre cada livro são listadas, como preço, número de páginas, ISBN e detalhes da edição.
Effective bandwidth refers to the bandwidth of an input signal that can be transmitted without distortion through a system. If the input signal bandwidth is larger than the system bandwidth, the output will be distorted. The signal and system bandwidths should match. Transmission impairments like attenuation, delay distortion, and noise can distort signals and introduce errors. Different types of cables like twisted pair, coaxial, and optical fiber have different characteristics for digital data transmission.
The document discusses key concepts in data transmission including:
1) Transmission occurs over guided or unguided media between a transmitter and receiver.
2) Signals can be analyzed in the frequency domain and have properties like frequency, spectrum, and bandwidth.
3) Both analog and digital signals are used to represent data for transmission.
This document provides an overview of principles of communication. It discusses key components of a communication system including the transmitter, communication channel, and receiver. It describes different forms of modulation used in analog and digital communication systems, including amplitude modulation, frequency modulation, and pulse modulation. It also discusses antennas, communication channels, receivers, and applications of communication systems like data transmission, fax, radio, television, and satellite communication.
This includes Digital signal data transmission, Base band and band pass transmission. Also detailed with PAM, PPM, PWM, PCM, DPCM, DM, ADM, ASK, PSK, FSK.
This document defines and describes key concepts in electronic communication systems including transmitters, channels, receivers, signal types (analog, digital, continuous, discrete), periodic and non-periodic signals, even and odd signals, and units of measurement such as decibels and dBm. It provides examples of converting between absolute power ratios and decibels, as well as converting between milliwatts and dBm.
Analog communication System Basic Introduction by A Sravan KumarAPPALASRAVANKUMAR
This document discusses analog communication systems and key concepts related to noise. It describes the basic communication process involving a sender, receiver, and communication channel. It defines noise as any unwanted signal added to the desired message signal. Noise can reduce signal bandwidth, require increased transmitting power, and cause misunderstanding of signals. Noise is classified as either external noise from man-made, atmospheric, or extraterrestrial sources, or internal noise such as thermal, shot, time transit time, and miscellaneous noises. The document also discusses signal-to-noise ratio, defined as the ratio of signal power to noise power, and how it is expressed in decibels. Finally, it mentions noise factor, noise figure, and noise temperature as related
This document provides an overview of wireless networks and technologies. It discusses the history of wireless communication from Marconi's invention of the wireless telegraph to modern cellular networks. It also covers key topics in wireless networking including broadband wireless, antennas and propagation, transmission impairments like noise and multipath, and error compensation techniques like forward error correction and diversity. The document is an introduction to wireless concepts for students intended to provide foundational knowledge.
The document discusses digital transmission fundamentals, including:
- Digital representation of analog signals involves sampling, quantization, and pulse code modulation.
- The sampling rate must be at least twice the bandwidth of the signal to allow perfect reconstruction.
- Quantization maps samples to discrete levels, introducing quantization error. More levels reduce error but increase transmission bandwidth needs.
- Digital transmission enables long distance communication by regeneration of the digital signal rather than analog amplification, overcoming distance limitations of analog systems.
This document discusses data and signals used in data communication. It defines analog and digital data, as well as continuous and discrete signals. Signals can be transformed into electromagnetic waves for transmission. Both signals and data can be either analog or digital. The key properties of signals, including amplitude, period, frequency, phase, and wavelength are described. The document also discusses how signals can be impaired by attenuation, distortion, and noise during transmission. The Nyquist sampling theorem and Shannon capacity theorem place important limits on maximum data transmission rates based on bandwidth and signal-to-noise ratio. Examples are provided to illustrate how to calculate transmission rates, signal levels, amplification, and bandwidth.
Ripple control is a power line communication method used by electric utilities to remotely control loads like water heaters and street lights. It works by superimposing a coded control signal onto the 50Hz voltage waveform.
While smart meters allow for two-way communication, ripple control still provides utilities faster load control during emergencies compared to wireless options. Grid sensing uses sensor networks to monitor the electric grid in real-time for issues like equipment failures. Load management through ripple control involves directly or indirectly controlling loads like water heaters during peak periods to reduce demand. Attenuation can cause receiving relays not to operate loads as intended, while amplification can cause interference in customer equipment. Utilities mitigate inappropriate signal levels by
Satellite communication analog and digital signalsAjay Kumar
This document discusses various sources of information and signals used in satellite communication, their characteristics, and applications. It describes primary information sources like speech, audio, video, and data. It then covers analog signals, including different types of analog signals and modulation schemes used. The document also discusses digital signals, examples of encoding digital data, and various digital modulation schemes. It provides advantages and disadvantages of both analog and digital signals.
Digital Communication System
Communication Channels
AWGN: Universal channel model
Band Limited Channel: Channel BW <Signal BW, ISI
Fading Channel: multipath waves
Basic Modulation Methods
Criteria for choosing Modulation Schemes
Power Efficiency: Required Eb/N for certain error probability over AWGN channel
Bandwidth Efficiency: no. of bits per second that can be transmitted on system bandwidth.
System Complexity: Amount of circuit involved and complexity
System Performance Parameters
Average SNR
Outage Probability: instantaneous prob. Exceed certain limit
Average BEP
Amount of Fading/severity of fading
Average Outage duration: O/P SNR fall below certain SNR
This document discusses various methods of information transmission including digital-to-digital, analog-to-digital, transmission modes, digital-to-analog, and analog-to-analog conversion. It describes techniques such as line coding, block coding, pulse code modulation, delta modulation, asynchronous/synchronous/isochronous transmission, and analog modulation methods including amplitude, frequency, and phase modulation. The key steps and processes involved in each conversion technique are explained, along with considerations for bandwidth and how analog or digital signals are represented.
The document discusses digital communication systems and outlines topics that will be covered, including digital data communication, multiplexing techniques, digital modulation and demodulation, and performance comparisons of modulation schemes. The objectives are to provide an overview of communication systems and concepts, discuss digital transmission methods and modulation types, and enable students to design simple communication systems and discuss industry trends.
1) Noise exists in all communication systems and degrades signal quality. It is caused by random movement of electrons and can be internal or external.
2) Thermal noise, also known as Johnson noise, is generated by thermal agitation of electrons in conductors. It is proportional to temperature and bandwidth.
3) Noise figure and noise temperature are used to measure the degradation of signal to noise ratio caused by components in a communication system. Lower noise figure and temperature indicate less degradation.
The Nyquist formula states that the maximum data rate supported by a bandwidth B is 2B bits per second. Doubling the bandwidth doubles the maximum data rate. Signals with more than two levels can represent more data per signal, with the formula becoming C = 2B log2M, where M is the number of signal levels. Shannon's channel capacity theorem defines the maximum reliable transmission rate C for a bandwidth B channel as C = B log2(1 + S/N), where S is the signal power and N is the noise power.
This document provides information about Ass. Prof. Ibrar Ullah who teaches communication systems at CECos University. It includes his educational background and contact information. The rest of the document is a chapter on sampling and pulse code modulation that is divided into sections covering topics like sampling, signal interpolation, and pulse code modulation. It also includes sections on noise, noise power, noise figure, and Friis' formula for amplifier cascades.
Most electronic communication signals can be represented by sine and cosine waves. Sine and cosine waves are periodic and can be converted between each other using trigonometric identities. Fourier analysis techniques such as Fourier series and Fourier transforms are used to represent signals in the time and frequency domains.
1) O documento apresenta sinopses de vários livros, incluindo O Sol Também é uma Estrela de Nicola Yoon, A Chave de Rebecca de Ken Follett e Irmãos de Sangue de Nora Roberts.
2) É fornecido contexto sobre os autores e suas obras, como vendas, prêmios recebidos e adaptações para outros meios.
3) Informações técnicas sobre cada livro são listadas, como preço, número de páginas, ISBN e detalhes da edição.
1) A new transmission electron microscope called Titan, costing over $4 million, has been installed at the Technion's Russell Berrie Nanotechnology Institute. It will allow researchers to see individual atoms and analyze chemical bonds between them.
2) A joint student team from Technion and Penn State won first place in the undergraduate category of a helicopter design competition sponsored by Bell Helicopter, with their design of an affordable two-seat training helicopter and new low-cost turbine engine.
3) The Technion has received over $200 million in donations in the last four months, including $30 million from Lorry Lokey for a new life sciences center, $20 million from Seymour Schulich for the chemistry faculty
Este documento describe los modos y componentes del discurso oral y escrito. Explica cuatro modos de organización del discurso: narrativo, descriptivo, expositivo y argumentativo. Luego analiza los componentes verbales y no verbales del discurso oral como gestos, distancia entre personas y entonación. Finalmente, examina elementos no verbales de la escritura como el formato y tipografía utilizados.
The document discusses various properties of signals including:
- Analog signals can have an infinite number of values while digital signals are limited to a set of values.
- Phase describes the position of a waveform relative to a reference point in time.
- Total energy and average power of continuous and discrete signals can be calculated through integrals and sums.
- Periodic, even, odd, exponential, and sinusoidal signals are described.
- Unit impulse and step signals are defined for both discrete and continuous time domains.
- A signal's frequency spectrum shows the collection of component frequencies and bandwidth is the range of these frequencies.
parametric method of power spectrum Estimationjunjer
The document discusses parametric methods of power spectrum estimation. It explains that parametric methods estimate the parameters of a mathematical model that describes the signal generation process. This involves selecting a model such as autoregressive (AR), moving average (MA), or autoregressive moving average (ARMA), estimating the model parameters from the data, and then using the estimated parameters to calculate the power spectrum. The document provides details on how to estimate the power spectrum using AR, MA, and ARMA models. It also discusses maximum entropy spectral estimation and high-resolution spectral estimation based on eigen-analysis.
This document summarizes research on applying speech enhancement techniques including spectral subtraction and Wiener filtering. The goals were to examine and simulate these techniques in Matlab. The techniques were tested on speech degraded by additive noise at different signal-to-noise ratios. Spectral subtraction removes noise by subtracting noise spectrum estimates from the degraded speech spectrum. Wiener filtering suppresses noise by multiplying the speech spectrum by a frequency response. Both techniques performed similarly at low noise, but Wiener filtering performed better at higher noise levels. Future work could include automatic noise detection and adaptation to changing noise.
El documento presenta una serie de actividades para dibujar la boca del cocodrilo Quique y peces según instrucciones. También incluye ejercicios para comparar números usando símbolos como <, = y >.
This document covers key concepts about signals including:
1) It defines continuous-time and discrete-time signals, and discusses the concepts of energy and power for both types of signals.
2) It provides the mathematical definitions of total energy, average power, and characterizes signals based on whether they have finite or infinite total energy and average power.
3) It discusses properties of exponential and sinusoidal signals, including that they have infinite total energy but finite average power.
4) It introduces common basic signals like the unit impulse and unit step signals in both continuous and discrete time.
Noice canclellation using adaptive filters with adpative algorithms(LMS,NLMS,...Brati Sundar Nanda
This document discusses and compares various adaptive filtering algorithms for noise cancellation, including LMS, NLMS, RLS, and APA. It finds that RLS converges the fastest but has the highest complexity, while LMS converges the slowest but is simplest. NLMS and APA provide a balance between convergence speed and complexity. The document implements these algorithms on a noise cancellation problem and finds that RLS achieves the highest SNR improvement and best noise cancellation, followed by APA, NLMS, and LMS.
This document provides an overview of principles of communication. It discusses key components of a communication system including the transmitter, communication channel, and receiver. It describes different forms of modulation used in analog and digital communication systems, including amplitude modulation, frequency modulation, and pulse modulation. It also discusses antennas, transmission media, data transmission methods like email and fax, and aspects of space communication.
This document provides an overview of telecommunication systems and communication engineering. It discusses analog and digital signals, different modulation techniques used in communication systems including amplitude modulation and frequency modulation. Key aspects covered include:
- Analog signals are continuous over time and amplitude while digital signals involve quantization.
- A basic communication system includes a source, transmitter to convert the signal to a transmission format, a channel with noise, a receiver to decode the signal, and a destination.
- Modulation involves varying properties of a carrier signal like amplitude, frequency, or phase to transmit a message signal over a channel.
- Common modulation techniques are amplitude modulation which varies signal strength, and frequency modulation which varies carrier frequency.
This document provides an overview of telecommunication systems and communication engineering. It discusses analog and digital signals, the components of a basic communication system including the source, transmitter, channel, receiver and destination. It describes different types of modulation used in communication systems including amplitude modulation, frequency modulation, and pulse modulation. It also includes block diagrams of wireless communication systems and their components such as the transmitter, encoder, noisy channel, decoder and receiver.
COMPUTER NETWORKS DATAS AND SIGNALS.pptxKALPANAC20
This document discusses analog and digital signals. It begins by explaining that data can be either analog or digital. Analog data is continuous and takes on a continuous range of values, while digital data is discrete and takes on discrete states represented by numbers like 0s and 1s. It then discusses analog signals, which can have an infinite number of values in a range, and digital signals, which have a limited number of discrete values. The document provides examples of analog signals like human voice and digital signals like computer memory. It also compares periodic and nonperiodic signals.
This document discusses concepts related to transmission impairments and channel capacity. It begins by defining different types of communication including simplex, half-duplex, and full-duplex. It then discusses sources of transmission impairment including attenuation, distortion, noise and how they degrade signals. It defines signal-to-noise ratio and how it is used to measure quality. Bandwidth and channel capacity are also mentioned. Examples are provided to illustrate key concepts like decibel calculation and analyzing problems related to signal attenuation and distortion.
This document provides an overview of physical layer concepts related to data transmission. It discusses how data is represented as signals and transmitted over communication media. It describes analog and digital signals, including their characteristics like frequency, period, phase, and bandwidth. It also covers different types of transmission media, including twisted pair cable, coaxial cable, and optical fiber, which are used to transmit electromagnetic signals representing data. The physical layer is responsible for moving data in the form of signals across the transmission medium.
This ppt contains information about concepts of wireless communication, signal propagation effects, spread spectrum, cellular systems, multiple access systems.
The communication system allows transmission and reception of information between two distant points. It consists of a transmitter that sends information, a channel that carries the signal, and a receiver that extracts the message. Communication systems can be analog, transmitting continuous signals, or digital, transmitting discrete signals encoded as 1s and 0s. The electromagnetic spectrum is divided into bands allocated to different applications like radio, TV, cellular etc. based on their frequencies and wavelengths. Modulation encodes the message onto a carrier signal, and multiplexing combines multiple messages for transmission.
The document discusses digital communication systems and their advantages over analog communication. It describes how analog signals are digitized using sampling and quantization. Sampling must occur at least twice the maximum frequency of the signal to avoid aliasing, as stated by the Nyquist sampling theorem. Quantization converts continuous amplitudes to discrete levels, causing quantization error and noise. Digital communication provides benefits like lower distortion and easier signal processing. Companding is discussed as a technique used in pulse code modulation to improve signal-to-noise ratio by compressing higher amplitudes before transmission.
This document provides a summary of key concepts in data communication and transmission including:
1) Communication models including simplex, half duplex, and full duplex transmission modes.
2) Analog and digital signals and their characteristics such as periodicity.
3) Concepts such as bandwidth, attenuation, noise, and Shannon's channel capacity formula that influence data transmission rates.
RF testing has remained hype for most of us. But seriously it is not so. It can be very interesting and one can develop a lot of interest in this if given an opportunity.
In this paper, authors have started with the some basic concepts of radio engineering which we studied in engineering and built upon these concepts to use in practical applications.
We have also described the basic principles of Signal Analyzer and Signal Generator which are the most common test tools used for any radio testing.
This document provides an overview of key concepts in communications systems, including:
1) It describes the basic components of a communications system including the input/output transducers, transmitter, channel, and receiver.
2) It discusses different types of signals that can be transmitted through a channel including analog modulation techniques like AM, FM and PM as well as digital modulation.
3) It provides an overview of electromagnetic waves and the electromagnetic spectrum used for wireless communication.
This document discusses key concepts in data transmission including:
1) Data transmission can occur over guided mediums like cables or unguided wireless mediums like air, and can be point-to-point, multi-point, simplex, half-duplex, or full-duplex.
2) Analog signals vary continuously over time while digital signals maintain constant levels that change abruptly, and periodic signals have a repeated pattern while aperiodic signals do not.
3) Factors that characterize signals include amplitude, frequency, period, phase, and wavelength. Signals can be analyzed in the frequency domain and represented by their frequency domain functions.
4) Digital data transmission has advantages over analog in being less susceptible
- The document discusses data communication fundamentals including data, signals, analog vs digital signals, and time domain vs frequency domain representations of signals.
- It defines key concepts such as bandwidth, bit rate, noise sources, and baseband vs broadband signals.
- Examples are provided to explain periodic and aperiodic signals, and how signals can be represented in both the time and frequency domains.
This document provides an overview of key concepts from a lecture on information and communication systems. It defines data, information, messages, and signals, explaining that messages contain information and are transmitted through signals. It also distinguishes between analog and digital information, noting that the natural world is analog while computers use discrete digital values. Additionally, it covers properties of signals like amplitude, frequency, and phase. Finally, it describes the different modes of communication including simplex, half-duplex, and full-duplex.
The document discusses topics related to data communication and computer networks including digital signals, transmission media, transmission impairments, and the data link layer.
Specifically, it covers:
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Telecommunications basics
1. 2. TELECOMMUNICATIONS BASICS
The purpose of any telecommunications system is to transfer information
from the sender to the receiver by a means of a communication channel.
The information is carried by a signal, which is certain physical quantity
that changes with time.
The signal can be a voltage proportional to the amplitude of the voice,
like in a simple telephone, a sequence of pulses of light in an optical fibre,
or a radio-electric wave irradiated by an antenna.
For analog signals, these variations are directly proportional to some
physical variable like sound, light, temperature, wind speed, etc. The
information can also be transmitted by digital binary signals, that will have
only two values, a digital one and a digital zero. Any analog signal can be
converted into a digital signal by appropriately sampling and then coding
it. The sampling frequency must be at least twice the maximum frequency
present in the signal in order to carry all the information contained
therein. Random signals are the ones that are unpredictable and can be
described only by statistical means.
Noise is a typical random signal, described by its mean power and
frequency distribution. A signal can be characterised by its behaviour over
time or by its frequency components, which constitute its spectrum. Some
examples of signals are shown in Figure TB 1.
Figure TB 1: Examples of signals
Any periodic signal is composed of many sinusoidal components, all of them
multiples of the fundamental frequency, which is the inverse of the period of
the signal. So a signal can be characterised either by a graph of its amplitude
over time, called a waveform, or a graph of of the amplitudes of its frequency
components, called a spectrum.
Figure TB 2: Waveforms, Spectrum and filters
2. Figure TB 2 shows how the same signal can be seen from two different
perspectives. The waveform can be displayed by an instrument called an
oscilloscope, while the spectrum can be displayed by what is called a
Spectrum Analyzer. The spectrum distribution relays very important
information about the signal and allows for the intuitive understanding of
the concept of filtering of electrical signals. In the example shown, the
signal is formed by the superposition of three sinusoidal components of
frequency f1, f2 and f3. If we pass this signal through a device that will
remove f2 and f3, the output is a pure sinusoidal at frequency f1.
We call this operation “Low Pass filtering” because it removes the
higher frequencies. Conversely, we can apply the signal to a “High
Pass Filter”, a device that will remove f1 and f2 leaving only a
sinusoidal signal at the f3 frequency. Other combinations are
possible, giving rise to a variety of filters. No physical device can
transmit all the infinite frequencies of the radio-electric spectrum,
so every device will always perform some extent of filtering to the
signal that goes through it. The bandwidth of a signal is the
difference between the highest and the lowest frequency that it
contains and is expressed in Hz (number of cycles per second).
While travelling through the communication channel, the signal is subject
to interference caused by other signals and is also affected by the electrical
noise always present in any electrical or optical component. Intra-channel
interference originates in the same channel as our signal. Co-channel
interference is due to the imperfection of the filters that will let in signals
from adjacent channels.
Consequently, the received signal will always be a distorted replica of the
transmitted signal, from which the original information must be retrieved
3. by appropriate means to combat the effect of interference and noise.
Furthermore, the received signal will be subject to attenuation and delay
that increase with the distance between the transmitter and the receiver.
Figure TB 3: Attenuation and delay
Although it is relatively simple to restore the amplitude of signal by means
of an electrical amplifier, the components of the amplifier will add
additional noise to the signal, so at very long distances where the received
signal is feeble, the amplifier will produce a signal so garbled with noise
that the information originally transmitted will no longer be retrievable.
One way to address this problem consists in converting the continuous
quantity carrying the information into a sequence of very simple symbols
which can be easier to recognise even at great distance. For instance, the
flag of a ship is a convenient way to distinguish the nationality of the ship
even at distances at which the letters on the hull cannot be read.
This technique has been extended to carry generalised messages by
assigning different position of flags to every letter of the alphabet, in an
early form of long distance telecommunications by means of digital or
numeric signals.
The limitation of this method is obvious; to be able to distinguish among,
say, 26 symbols corresponding to each letters of the alphabet, one must be
quite close to the communicating ship.
4. On the other hand, if we code each letter of the alphabet in a sequence of
only two symbols, these symbols can be distinguished at much longer
distance, for example the dot and dashes of the telegraph system.
The process of transforming a continuous analog signal into a
discontinuous digital one is called Analog to Digital Conversion (ADC),
and conversely we must have a Digital to Analog Converter (DAC) at the
receiving end to retrieve the original information.
This is the reason why most modern telecommunication systems use
digital binary signals to convey all sorts of information in a more robust
way. The receiver must only distinguish between two possible symbols, or
in other words between two possible values of the received bit (binary
digit). For instance, the CD has replaced the vinyl record, and analogue
television is being replaced by digital television. Digital signals can use less
bandwidth, as exemplified by the “digital dividend” currently being
harnessed in many countries which consists in bandwidth that has become
available thanks to the transition from analog to digital transmission in
TV broadcasting.
Although in the process of converting from an analog to a digital
information system there is always some loss of information, we can
engineer the system so as to make this loss negligible.
Figure TB 4: Undersampled Image
For example, in a digital camera we can choose the number of bits used to
record the image.
The greater the number of bits (proportional to the amount of megapixels),
the better the rendering, but more memory will be used and longer time to
transmit the image will be needed.
So most modern communication systems deal with digital signals, although
the original variable that we want to transmit might be analog, like the voice.
5. It can be shown that any analog signal can be reconstructed from discrete
samples if the sampling rate is at least twice as high as the highest frequency
content of the signal.
Figure TB 5: detection of a noisy signal
Then each sample is coded in as many bits as necessary to achieve the desired
amount of precision.
These bits can now be efficiently stored or transmitted, since for the recovery
of the information one needs to distinguish among only two states, and not
among the infinite nuances of an analog signal.
6. This is shown in Figure TB 5, where the original data consists of the 0 1 0
1 1 1 0 sequence. The 0's are represented as zero volts and the 1's as 1 V.
As the signal moves towards the receiver, its amplitude will diminish. This
effect is called "attenuation" and is shown in the figure. Likewise, there
will also be a delay as the signal moves from the transmitter to the
receiver, the variability in the delay of the received signal is called jitter.
Attenuation, noise or jitter (or their combination) if severe enough, can
cause a detection error. An amplifier can be used to overcome the
attenuation, but the electrical noise always present in the system will add
to the received signal.
The noisy received signal is therefore quite different from the original
signal, but in a digital system we can still recover the information
contained by sampling the received signal at the correct time and
comparing the value at the sampling time with a suitable threshold
voltage. In this example the noise received signal has a peak of 1.8 V, so
we might choose e threshold voltage of 1.1 V. If the received signal is
above the threshold, the detector will output a digital 1, otherwise, it will
output a 0. In this case we can see that because of the effect of the noise
the fifth bit was erroneously detected as a zero.
Transmission errors can also occur if the sampling signal period is different
from that of the original data (difference in the clock rates), or if the
receiver clock is not stable enough (jitter).
Any physical system will have an upper limit in the frequencies that will
transmit faithfully (the bandwidth of the system), higher frequencies will
be blocked, so the abrupt rise and fall of the voltage will be smoothed out
as the signal goes through the channel.
Therefore, we must make sure that each of the elements of the system has
enough bandwidth to handle the signal. On the other hand, the greater
the bandwidth of the receiver system, the greater the amount of the noise
that will affect the received signal.
Modulation
The robustness of the digital signal is also exemplified by the fact that it
was chosen for the first trials of radio transmission. Marconi showed the
feasibility of long distance transmission, but pretty soon realised that there
was a need to share the medium among different users.
7. This was achieved by assigning different carrier frequencies which were
modulated by each user’s message. Modulation is a scheme to modify the
amplitude, frequency or phase of the carrier according with the information
one wants to transmit. The original information is retrieved at destination
by the corresponding demodulation of the received signal.
Figure TB 6: Sinusoidal Carrier Signal
Figure TB 6 shows a carrier signal with Amplitude A, phase θ, and
frequency fo which is the reciprocal of the period T.
The combination of different modulation schemes has resulted in a
plethora of modulation techniques depending on which aspect one wants
to optimise: robustness against noise, amount of information transmitted
per second (capacity of the link in bits/second) or spectral efficiency
(number of bits/s per Hertz).
For instance, BPSK -Binary Phase Shift Keying- is a very robust
modulation technique but transmits only one bit per symbol, while 256
QAM -Quaternary Amplitude Modulation- will carry 8 bits per symbol,
thus multiplying by a factor of eight the amount of information
transmitted per second, but to correctly distinguish amongst the 256
symbols transmitted, the received signal must be very strong as compared
with the noise (a very high S/N -Signal/Noise ratio- is required).
The ultimate measure of quality in digital transmission is the BER -Bit
Error Rate- which corresponds to the fraction of erroneously decoded bits.
8. Typical values of BER range between 10-3
and 10-9
.
The modulation also allows us to choose which range of frequency we
want to use for a given transmission. All frequencies are not created equal
and the choice of the carrier frequency is determined by legal, commercial
and technical constraints.
Multiplexing and duplexing
In general, the sharing of a channel among different users is called
multiplexing.
This is shown in Figure TB 7.
Assigning different carrier frequencies to different users is called FDMA
-Frequency Division Multiple Access-.
An alternative technique consists in assigning different time slots to
different users, in what is known as TDMA -Time Division Multiple
Access-, or even different codes in CDMA -Code Division Multiple
Access- where the different users are recognised at the receiver by the
particular mathematical code assigned to them. See Figure TB 8.
By using two or more antennas simultaneously, one can take advantage of
the different amount of fading introduced in the different paths to the
receiver establishing a difference among users in what is known as SDMA
- Space Division Multiple Access-, a technique employed in the MIMO
-Multiple Input,Multiple Output- systems that have gained popularity
recently.
9. Figure TB 8: Medium Sharing techniques
Most communication systems transmit information in both directions, for
instance from the Base Station to the subscriber in what is called the
downlink, and from the subscriber to the base station in the uplink.
To accomplish this, the channel must be shared between the two
directions giving rise respectively to FDD -Frequency Division Duplexing-
and TDD -Time Division Duplexing-.
Conclusions
The communication system must overcome the noise and interference to
deliver a suitable replica of the signal to the receiver.
10. The capacity of the communication channel in bits/second is proportional
to the bandwidth in Hz and to the logarithm of the S/N ratio.
Modulation is used to adapt the signal to the channel and to allow several
signals to share the same channel. Higher order modulation schemes allow
for a higher transmission rate, but require higher S/N ratio.
The channel can be shared by several users that occupy different
frequencies, different time slots, different codes or by taking advantage of
different propagation characteristics in what is called spatial multiplexing.
For more information and slides covering this topic please visit
http://wtkit.org/groups/wtkit/wiki/820cb/download_page.html