Sampling Pulse Amplitude Modulation Pulse Code Modulation Sampling
Total Page：16
File Type：pdf, Size：1020Kb
Load more
Recommended publications
-
Bit & Baud Rate
What’s The Difference Between Bit Rate And Baud Rate? Apr. 27, 2012 Lou Frenzel | Electronic Design Serial-data speed is usually stated in terms of bit rate. However, another oft- quoted measure of speed is baud rate. Though the two aren’t the same, similarities exist under some circumstances. This tutorial will make the difference clear. Table Of Contents Background Bit Rate Overhead Baud Rate Multilevel Modulation Why Multiple Bits Per Baud? Baud Rate Examples References Background Most data communications over networks occurs via serial-data transmission. Data bits transmit one at a time over some communications channel, such as a cable or a wireless path. Figure 1 typifies the digital-bit pattern from a computer or some other digital circuit. This data signal is often called the baseband signal. The data switches between two voltage levels, such as +3 V for a binary 1 and +0.2 V for a binary 0. Other binary levels are also used. In the non-return-to-zero (NRZ) format (Fig. 1, again), the signal never goes to zero as like that of return- to-zero (RZ) formatted signals. 1. Non-return to zero (NRZ) is the most common binary data format. Data rate is indicated in bits per second (bits/s). Bit Rate The speed of the data is expressed in bits per second (bits/s or bps). The data rate R is a function of the duration of the bit or bit time (TB) (Fig. 1, again): R = 1/TB Rate is also called channel capacity C. If the bit time is 10 ns, the data rate equals: R = 1/10 x 10–9 = 100 million bits/s This is usually expressed as 100 Mbits/s. -
The Three Myths of Optical Capacity Scaling How to Maximize and Monetize Subsea Cable Capacity
WHITE PAPER The Three Myths of Optical Capacity Scaling How to Maximize and Monetize Subsea Cable Capacity MYTH 1 Scaling BAUD RATE increases spectral efficiency, thereby increasing total subsea fiber capacity MYTH 2 Scaling MODULATION ORDER increases spectral efficiency, thereby increasing total subsea fiber capacity MYTH 3 Scaling INTEGRATION has no effect on spectral efficiency or subsea fiber capacity AXES OF SCALABILITY Capacity/wave Capacity/device Baud G/Wave 100 Gbaud 800 Gb/s+ 2.4 Tb/s 600 Gb/s 66 Gbaud 1.2 Tb/s 200 Gb/s 500 Gb/s 33 Gbaud 100 Gb/s Modulation Fiber capacity 6 Carrier SC 1.2 @ 16QAM QPSK 8QAM 16QAM 237.5 GHz 64QAM CS-64QAM Multi-channel Super-channel Gb/s/unit FigureFigure 1: 1: Three The Three axes Axes of opticalof Optical scalability Scaling The Three Axes of Optical Scaling Figure 1 shows the three axes that are needed for optical scaling—baud rate, modulation order and integration. This paper will discuss scaling along each of these axes, but it is important to clarify exactly what is being scaled. There are at least three interpretations: • Increasing the data rate per wavelength • Increasing the capacity per line card or appliance • Increasing the total fiber capacity, or spectral efficiency These can potentially be scaled independently, or in concert as transponder technology evolves. In subsea deployments total fiber capacity, or spectral efficiency, is usually the dominant factor in determining overall network economics, so it becomes extremely important to understand the most effective way to achieve total capacity, especially when scaling baud rate has become a focal point for many dense wavelength-division multiplexing (DWDM) vendors today. -
Quadrature Amplitude Modulation (QAM) Or Amplitude Phase Shift Keying (APSK) S(T ) = a Sin(2Π F T + )
ΕΠΛ 427: ΚΙΝΗΤΑ ΔΙΚΤΥΑ ΥΠΟΛΟΓΙΣΤΩΝ (MOBILE NETWORKS) Δρ. Χριστόφορος Χριστοφόρου Πανεπιστήμιο Κύπρου - Τμήμα Πληροφορικής Modulation Techniques (Τεχνικές Διαμόρφωσης) Recall (Process and Elements of Radio Transmission) 1 Modulation Demodulation Topics Discussed 2 Digital Modulation Bit rate, Baud rate Basic Digital Modulation Techniques (ASK, FSK, PSK, QAM) Constellation diagrams Factors that influence the choice of Digital Modulation Scheme – Power Efficiency, Bandwidth Efficiency Modulation 3 Message Signal (Data to be transmitted) Carrier signal with frequency fc Controlling the Amplitude of the carrier signal (ASK) Controlling the Frequency of the carrier signal (FSK) Controlling the Phase of the Modulated Signals Modulated carrier signal (PSK) Analog and Digital Signals Αναλογικά και Ψηφιακά Σήματα 4 Means by which data are propagated over a medium (Οι τρόποι με τους οποίους τα δεδομένα διαδίδονται μέσω κάποιου μέσου). An Analog Signal is a continuously varying electromagnetic wave (ένα συνεχόμενο εναλλασσόμενο ηλεκτρομαγνητικό κύμα) that may be propagated over a variety of media: Wire, fiber optic, coaxial, space (wireless) A digital signal is a sequence of discrete voltage pulses (είναι μια αλληλουχία διακριτών παλμών τάσης) that can be transmitted over a wire medium: E.g., a constant positive level of voltage to represent bit 1 and a constant negative level to represent bit 0. Modulation for Wireless Digital Modulation 5 Digital modulation is the process by which an analog carrier wave is modulated to include a discrete (digital) signal. (Ψηφιακή διαμόρφωση είναι η διαδικασία κατά την οποία ένας μεταφορέας αναλογικού σήματος διαμορφώνεται έτσι ώστε να συμπεριλάβει ένα διακριτό (ψηφιακό) σήμα (π.χ., 1 or 0)) Digital modulation methods can be considered as Digital-to- Analog conversion, and the corresponding Demodulation (e.g., at the Receiver) as Analog-to-Digital conversion. -
De-Mystifying Spectral Compatibility of Bonded Copper Systems - Why DMT Is Superior to SHDSL
White Paper De-Mystifying Spectral Compatibility of Bonded Copper Systems - Why DMT is Superior to SHDSL July 2010 Copyright © 2010 Positron Access Solutions, Inc. All rights reserved. Information in this document is subject to change without notice. Doc#: WP-2001-0710 White Paper: De-Mystifying Spectral Compatibility Table of Contents Abstract ....................................................................................... 3 Introduction ................................................................................. 4 The Basic Mechanism of Spectral Impact .................................. 6 Legacy HDSL/SHDSL Systems Confined by Overlap Spectra Design ...................................................................... 7 DMT’s Simplicity, Performance and Predictability Mitigate It’s Impact on ADSL/ADSL2+ ....................................................... 10 Why Enhanced SHDSL also Falls Short ..................................... 13 Proving it with Numbers – Data Supporting DMT’s Superiority .. 16 Conclusion ................................................................................... 19 References ................................................................................... 20 Doc#: WP-2001-0710 2 White Paper: De-Mystifying Spectral Compatibility Abstract This paper compares the spectral impact of symmetric DMT and SHDSL systems and provides clear evidence as to why DMT systems provide superior spectral compatibility, especially when they’re enhanced with MIMO on DMT functionality. It discusses the major -
Multiplexing with NMEA 0183 You Don’T Need State-Of-The-Art Gear to Build a Cost-Effective Onboard Network
ELECTRONICS The MiniPlex Lite multiplexer allows you to link wind instruments (above) and AIS data (right) to your computer. Multiplexing with NMEA 0183 You don’t need state-of-the-art gear to build a cost-effective onboard network. n the last three years, PS has looked autopilots, wind sensors, Automatic NMEA 0183 PRIMER Iat several ways to integrate per- Identification System (AIS) devices, NMEA 0183 is a serial protocol nor- sonal computers into our navigation etc.—still use it to communicate. New mally transmitting at 4,800 baud. For routine. In July 2006, we looked at and expensive devices meeting the comparison, this is about one-tenth of building a custom mini-computer for NMEA 2000 standard (see “Market the speed of a basic dial-up Internet onboard duties. In September 2006, Notes,” page 29) are readily available, connection. we carried out a broad review of nav but in the spirit of doing more with NMEA 0183 is based on the Elec- software with several updates in 2007 less, this article looks at ways we can tronic Industry Association’s RS-422 and 2008. get the most of our existing electronic standard, a close cousin of the RS-232 This is a fast-moving target, and equipment. standard. RS-422 uses differential several recent technological advances When it comes time to add more voltages while RS-232 is single-ended. are changing the playing field. The sensors to your navigation system This means that RS-422 is much more mainstream introduction of solid (such as an AIS unit) or integrate your resistant to electrical noise and can state memory (no more spinning hard PC into the system, making connec- transmit over much longer wire runs. -
Data Encodingencoding
ChapterChapter 3:3: DataData EncodingEncoding Raj Jain Professor of CIS The Ohio State University Columbus, OH 43210 [email protected] http://www.cis.ohio-state.edu The Ohio State University Raj Jain 3-1 Overview q Coding design consideration q Codes for q digital data to digital signal q Digital data, analog signal q Analog signal, digital data q Analog signal, analog data The Ohio State University Raj Jain 3-2 Coding Terminology Pulse +5V +5V 0 0 Bit -5V -5V q Signal element: Pulse q Unipolar: All positive or All negative voltage q Bipolar: Positive and negative voltage q Mark/Space: 1 or 0 q Modulation Rate: 1/Duration of the smallest element =Baud rate q Data Rate: Bits per second q Data Rate = Fn(Bandwidth, signal/noise ratio, encoding) The Ohio State University Raj Jain 3-3 Coding Design Bits 0100011100000 +5V NRZ 0 -5V Clock Manchester NRZI q Pulse width indeterminate: Clocking q DC, Baseline wander q No line state information q No error detection/protection q No control signals q High bandwidth q Polarity mix-up ⇒ Differential (compare polarity) The Ohio State University Raj Jain 3-4 Digital Signal Encoding Formats The Ohio State University Figure3.2 Raj Jain 3-5 Digital Signal Encoding Formats q Nonreturn-to-Zero-Level (NRZ-L) 0= high level 1= low level q Nonreturn to Zero Inverted (NRZI) 0= no transition at beginning of interval (one bit time) 1= transition at beginning of interval q Bipolar-AMI 0=no line signal 1= positive or negative level,alternating for successive ones The Ohio State University Raj Jain 3-6 Encoding Formats (Cont) -
Telecommunications Glossary (Pdf)
31 Segovia, San Clemente, CA 92672 (949) 369-3867 • [email protected] This file can be found on the TEC website at http://www.tecweb.org/eddevel/telecon/glossary.pdf Telecommunications Glossary from "A Technical Guide to Teleconferencing and Distance Learning," 3rd edition A 2 N 59 B 7 O 62 C 13 P 64 D 22 Q 70 E 28 R 71 F 31 S 74 G 36 T 83 H 38 U 88 I 42 V 90 J 46 W 93 K 48 X 95 L 49 Y 95 M 52 Z 95 Telecommunications Glossary/1 A Access Channels: Dedicated channels giving nondiscriminatory access to a local cable system by the public, government agencies or educational institutions. ACCUNET Switched Digital Services: High-speed dial-up digital data services offered by AT&T for full duplex digital transmission at speeds of 56, 64, 384 and 1536 kbps. Uses include data, voice and video services. Acoustic Coupler: A device that allows a conventional telephone handset to feed its signal into a modem, as opposed to direct couplers, which feed the modulated/demodulated signal directly into the phone line. Acoustic Echo Canceller: All speakerphones have some form of adaptive echo canceller that produces a synthetic replica of the potential echo to subtract from the transmit audio. Most units have a center clipping echo suppresser to remove the residual echo from the transmit signal. The goal of the acoustic echo canceller is to reduce the amount of direct and reverberant loudspeaker coupling to the microphone to prevent echo. To achieve this, the algorithms used in today's devices require an audio system that is feedback stable. -
Digital & Analog Transmission
Chapter 4: Digital Transmission (Line coding, Block coding, Scrambling) Digital to digital conversion (Line Coding) Converting a sequence of data bits (text, numeric, audio, or video) into a digital signal, at the sender, then recovering the original bit sequence from the signal, at the destination data rate ≡ bit rate(N) b/s, signal rate(S) ≡ baud ratechange/s (Hz) Let r bit/change, Nmax = S * r * 1/c where c is and usually assumed ½ For the average calculations of S&N The goal is to increase the data rate (information flow) while decreasing band rate (better utilization of channel BW, cheaper links) Factors to consider in digital signaling: Long strings of 0’s or 1’s causes a drift of the obtained baseline, hence “baseline wandering” that leads to incorrect bit decoding. 1) Baseline wandering: The receiver averages the signal power (Baseline), and uses it to decode the received signal bit value. 2) DC components: Constant level for long period of time creates very low frequency components in the frequency spectrum, that might not pass through some medium (e.g., TP of 200Hz 3000Hz). Hence, we need to remove the DC from the Digital Signal . 3) Self-Synchronization: To match the sender and receiver clocks, hence match the bit intervals at both ends for correct decoding. Transitions in the digital signal act as self-synch altering the receiver to the start, mid, or end of the bit, resetting its clock in case it is out of synch. 4) Built in error detection: It is good to add extra bits to the Tx data for error detection (and possibly correct). -
Data Communication 7
Data Communication & Networking Chapter 4 Digital Transmission 4.1 44--11 DIGITALDIGITAL--TOTO--DIGITALDIGITAL CONVERSION In this section, we see how we can represent digital data by using digital signals. signals.The conversion involves three techniques: techniques: line coding, block coding , and scrambling. Line coding is always neededneeded;;block coding and scrambling may or may not be needed. Topics discussed in this section: . Line Coding . Line Coding Schemes . Block Coding . Scrambling 4.2 Line Coding Converting a string of 1’s and 0’s (digital data) into a sequence of signals that denote the 1’s and 0’s. For example a high voltage level (+V) could represent a “1” and a low voltage level (0 or -V) could represent a “0”. 4.3 Figure 4.1 Line coding and decoding 4.4 Mapping Data symbols onto Signal levels A data symbol (or element) can consist of a number of data bits: 1 , 0 or 11, 10, 01, …… A data symbol can be coded into a single signal element or multiple signal elements 1 -> +V, 0 -> -V 1 -> +V and -V, 0 -> -V and +V The ratio ‘r’ is the number of data elements carried by a signal element. 4.5 Relationship between data rate and signal rate The data rate defines the number of bits sent per sec - bps. It is often referred to the bit rate. The signal rate is the number of signal elements sent in a second and is measured in bauds. It is also referred to as the modulation rate. Goal is to increase the data rate whilst reducing the baud rate. -
ISACA Glossary of Terms English-Spanish
ISACA® Glossary of Terms English-Spanish Third edition (2015) ACKNOWLEDGMENTS The ISACA® Glossary of Terms has been translated into Spanish (terms only) by a professional translation vendor and reviewed by many volunteers. The verified and approved translation of this glossary will help reduce the time, cost, and inconsistencies of ISACA Spanish translations. All of the ISACA members who participated in the review of the three editions of the translated glossary deserve our thanks and gratitude. Expert Translation Reviewers Alfonso Javier Mateluna Concha, CISA, CISM, CRISC, Chile Arnoldo Altamirano, CISA, Costa Rica Daniel Morales, CISA, Costa Rica Edson Marcelo Vittoriano Piuzzi, Sr., CISM, Chile Fabiola Paulina Moyón Constante, CISA, Ecuador Freddy Grey, CISA, CISM, Chile Jorge Serrano, CISA, CGEIT, CRISC, Chile Juan Davila Ramirez, CISA, CISM, Peru Larry Llirán, CISA, CISM, Puerto Rico Lolita E. Vargas-DeLeon, CISA, CIA, CPA, MIBA, Puerto Rico Luis A. Capua, CISM, CRISC, Argentina Luis Diego León, CISA, Costa Rica Luis Enrique Sánchez Crespo, Spain Marcelo Hector Gonzalez, CISA, CRISC, Argentina Marco Gámez, CISA, CRISC, Costa Rica Maria Patricia Prandini, CISA, CRISC, Argentina Pablo Caneo, CISA, CGEIT, CRISC, Chile Pablo Fernández, CISA, CRISC, Costa Rica Reyna Ramirez Montes, Mexico Salomon Rico, CISA, CISM, CGEIT, Mexico Sergio Molanphy, CISM, CRISC, Chile Victor Adalmer Vasquez Mejia, CISA, CISM, CRISC, Colombia FEEDBACK Please contact the ISACA Translation Manager at [email protected] for any comments or suggested changes. Abend -
A Guide to Networking Terminology
TO *** 'Cq REFERENCE \V TECHNICAL J NBS NOTE 803 h/ %TES O* too .sea 1174 U.S. ARTMENT OF OMMERCE National Bureau of Standards NATIONAL BUREAU OF STANDARDS The National Bureau of Standards' was established by an act of Congress March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology, the Institute for Computer Sciences and Technology, and the Office for Information Programs. THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consistent system of physical measurement; coordinates that system with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of a Center for Radiation Research, an Office of Meas- urement Services and the following divisions: Applied Mathematics — Electricity — Mechanics — Heat — Optical Physics — Nuclear 2 8 Sciences — Applied Radiation ~ — Quantum Electronics " — Electromagnetics — Time s and Frequency — Laboratory Astrophysics " — Cryogenics ". THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research leading to improved methods of measurement, standards, and data on the properties of well-characterized materials needed by industry, commerce, educational institutions, and Government; provides advisory and research services to other Government agencies; and develops, produces, and distributes standard reference materials. -
Chapter 6 Information Sources and Signals
Chapter 6 Information Sources and Signals 1 Big Idea in Data Source Communications: Compres. Scramb. A conceptual Encoder TX framework for a data communications system. Multiple Modulator sources send to CH multiple destinations through an underlying physical channel RX Each of the boxes corresponds to one subtopic of data communications: 2 The Subtopics of Data Communications • Information Sources – The source of information can be either analog or digital – Important concepts include characteristics of signals, such as amplitude, frequency, and phase, and classification as either periodic or aperiodic • Conversion between analog and digital representations of information • Source Encoder and Decoder – Once information has been digitized, digital representations can be transformed and converted – Concepts include data compression and consequences for communications 3 The Subtopics of Data Communications • Encryptor and Decryptor – To protect information and keep it private, the information can be encrypted (i.e., scrambled) before transmission and decrypted upon reception – Concepts include cryptographic techniques and algorithms • Channel Encoder and Decoder – Channel coding is used to detect and correct transmission errors – Topics include methods to detect and limit errors – Practical techniques like parity checking, checksums, and cyclic redundancy codes that are employed in computer networks • Multiplexor and Demultiplexor – Multiplexing refers to the way information from multiple sources is combined for transmission across a shared