Multiplexing and Sampling Theory
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Discrete Cosine Transform Based Image Fusion Techniques VPS Naidu MSDF Lab, FMCD, National Aerospace Laboratories, Bangalore, INDIA E.Mail: [email protected]
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by NAL-IR Journal of Communication, Navigation and Signal Processing (January 2012) Vol. 1, No. 1, pp. 35-45 Discrete Cosine Transform based Image Fusion Techniques VPS Naidu MSDF Lab, FMCD, National Aerospace Laboratories, Bangalore, INDIA E.mail: [email protected] Abstract: Six different types of image fusion algorithms based on 1 discrete cosine transform (DCT) were developed and their , k 1 0 performance was evaluated. Fusion performance is not good while N Where (k ) 1 and using the algorithms with block size less than 8x8 and also the block 1 2 size equivalent to the image size itself. DCTe and DCTmx based , 1 k 1 N 1 1 image fusion algorithms performed well. These algorithms are very N 1 simple and might be suitable for real time applications. 1 , k 0 Keywords: DCT, Contrast measure, Image fusion 2 N 2 (k 1 ) I. INTRODUCTION 2 , 1 k 2 N 2 1 Off late, different image fusion algorithms have been developed N 2 to merge the multiple images into a single image that contain all useful information. Pixel averaging of the source images k 1 & k 2 discrete frequency variables (n1 , n 2 ) pixel index (the images to be fused) is the simplest image fusion technique and it often produces undesirable side effects in the fused image Similarly, the 2D inverse discrete cosine transform is defined including reduced contrast. To overcome this side effects many as: researchers have developed multi resolution [1-3], multi scale [4,5] and statistical signal processing [6,7] based image fusion x(n1 , n 2 ) (k 1 ) (k 2 ) N 1 N 1 techniques. -
Digital Signals
Technical Information Digital Signals 1 1 bit t Part 1 Fundamentals Technical Information Part 1: Fundamentals Part 2: Self-operated Regulators Part 3: Control Valves Part 4: Communication Part 5: Building Automation Part 6: Process Automation Should you have any further questions or suggestions, please do not hesitate to contact us: SAMSON AG Phone (+49 69) 4 00 94 67 V74 / Schulung Telefax (+49 69) 4 00 97 16 Weismüllerstraße 3 E-Mail: [email protected] D-60314 Frankfurt Internet: http://www.samson.de Part 1 ⋅ L150EN Digital Signals Range of values and discretization . 5 Bits and bytes in hexadecimal notation. 7 Digital encoding of information. 8 Advantages of digital signal processing . 10 High interference immunity. 10 Short-time and permanent storage . 11 Flexible processing . 11 Various transmission options . 11 Transmission of digital signals . 12 Bit-parallel transmission. 12 Bit-serial transmission . 12 Appendix A1: Additional Literature. 14 99/12 ⋅ SAMSON AG CONTENTS 3 Fundamentals ⋅ Digital Signals V74/ DKE ⋅ SAMSON AG 4 Part 1 ⋅ L150EN Digital Signals In electronic signal and information processing and transmission, digital technology is increasingly being used because, in various applications, digi- tal signal transmission has many advantages over analog signal transmis- sion. Numerous and very successful applications of digital technology include the continuously growing number of PCs, the communication net- work ISDN as well as the increasing use of digital control stations (Direct Di- gital Control: DDC). Unlike analog technology which uses continuous signals, digital technology continuous or encodes the information into discrete signal states (Fig. 1). When only two discrete signals states are assigned per digital signal, these signals are termed binary si- gnals. -
Spread Spectrum and Wi-Fi Basics Syed Masud Mahmud, Ph.D
Spread Spectrum and Wi-Fi Basics Syed Masud Mahmud, Ph.D. Electrical and Computer Engineering Dept. Wayne State University Detroit MI 48202 Spread Spectrum and Wi-Fi Basics by Syed M. Mahmud 1 Spread Spectrum Spread Spectrum techniques are used to deliberately spread the frequency domain of a signal from its narrow band domain. These techniques are used for a variety of reasons such as: establishment of secure communications, increasing resistance to natural interference and jamming Spread Spectrum and Wi-Fi Basics by Syed M. Mahmud 2 Spread Spectrum Techniques Frequency Hopping Spread Spectrum (FHSS) Direct -Sequence Spread Spectrum (DSSS) Orthogonal Frequency-Division Multiplexing (OFDM) Spread Spectrum and Wi-Fi Basics by Syed M. Mahmud 3 The FHSS Technology FHSS is a method of transmitting signals by rapidly switching channels, using a pseudorandom sequence known to both the transmitter and receiver. FHSS offers three main advantages over a fixed- frequency transmission: Resistant to narrowband interference. Difficult to intercept. An eavesdropper would only be able to intercept the transmission if they knew the pseudorandom sequence. Can share a frequency band with many types of conventional transmissions with minimal interference. Spread Spectrum and Wi-Fi Basics by Syed M. Mahmud 4 The FHSS Technology If the hop sequence of two transmitters are different and never transmit the same frequency at the same time, then there will be no interference among them. A hopping code determines the frequencies the radio will transmit and in which order. A set of hopping codes that never use the same frequencies at the same time are considered orthogonal . -
How I Came up with the Discrete Cosine Transform Nasir Ahmed Electrical and Computer Engineering Department, University of New Mexico, Albuquerque, New Mexico 87131
mxT*L. BImL4L. PRocEsSlNG 1,4-5 (1991) How I Came Up with the Discrete Cosine Transform Nasir Ahmed Electrical and Computer Engineering Department, University of New Mexico, Albuquerque, New Mexico 87131 During the late sixties and early seventies, there to study a “cosine transform” using Chebyshev poly- was a great deal of research activity related to digital nomials of the form orthogonal transforms and their use for image data compression. As such, there were a large number of T,(m) = (l/N)‘/“, m = 1, 2, . , N transforms being introduced with claims of better per- formance relative to others transforms. Such compari- em- lh) h = 1 2 N T,(m) = (2/N)‘%os 2N t ,...) . sons were typically made on a qualitative basis, by viewing a set of “standard” images that had been sub- jected to data compression using transform coding The motivation for looking into such “cosine func- techniques. At the same time, a number of researchers tions” was that they closely resembled KLT basis were doing some excellent work on making compari- functions for a range of values of the correlation coef- sons on a quantitative basis. In particular, researchers ficient p (in the covariance matrix). Further, this at the University of Southern California’s Image Pro- range of values for p was relevant to image data per- cessing Institute (Bill Pratt, Harry Andrews, Ali Ha- taining to a variety of applications. bibi, and others) and the University of California at Much to my disappointment, NSF did not fund the Los Angeles (Judea Pearl) played a key role. -
F. Circuit Switching
CSE 3461: Introduction to Computer Networking and Internet Technologies Circuit Switching Presentation F Study: 10.1, 10.2, 8 .1, 8.2 (without SONET/SDH), 8.4 10-02-2012 A Closer Look At Network Structure: • network edge: applications and hosts • network core: —routers —network of networks • access networks, physical media: communication links d. xuan 2 1 The Network Core • mesh of interconnected routers • the fundamental question: how is data transferred through net? —circuit switching: dedicated circuit per call: telephone net —packet-switching: data sent thru net in discrete “chunks” d. xuan 3 Network Layer Functions • transport packet from sending to receiving hosts application transport • network layer protocols in network data link network physical every host, router network data link network data link physical data link three important functions: physical physical network data link • path determination: route physical network data link taken by packets from source physical to dest. Routing algorithms network network data link • switching: move packets from data link physical physical router’s input to appropriate network data link application router output physical transport network data link • call setup: some network physical architectures require router call setup along path before data flows d. xuan 4 2 Network Core: Circuit Switching End-end resources reserved for “call” • link bandwidth, switch capacity • dedicated resources: no sharing • circuit-like (guaranteed) performance • call setup required d. xuan 5 Circuit Switching • Dedicated communication path between two stations • Three phases — Establish (set up connection) — Data Transfer — Disconnect • Must have switching capacity and channel capacity to establish connection • Must have intelligence to work out routing • Inefficient — Channel capacity dedicated for duration of connection — If no data, capacity wasted • Set up (connection) takes time • Once connected, transfer is transparent • Developed for voice traffic (phone) g. -
Reception Performance Improvement of AM/FM Tuner by Digital Signal Processing Technology
Reception performance improvement of AM/FM tuner by digital signal processing technology Akira Hatakeyama Osamu Keishima Kiyotaka Nakagawa Yoshiaki Inoue Takehiro Sakai Hirokazu Matsunaga Abstract With developments in digital technology, CDs, MDs, DVDs, HDDs and digital media have become the mainstream of car AV products. In terms of broadcasting media, various types of digital broadcasting have begun in countries all over the world. Thus, there is a demand for smaller and thinner products, in order to enhance radio performance and to achieve consolidation with the above-mentioned digital media in limited space. Due to these circumstances, we are attaining such performance enhancement through digital signal processing for AM/FM IF and beyond, and both tuner miniaturization and lighter products have been realized. The digital signal processing tuner which we will introduce was developed with Freescale Semiconductor, Inc. for the 2005 line model. In this paper, we explain regarding the function outline, characteristics, and main tech- nology involved. 22 Reception performance improvement of AM/FM tuner by digital signal processing technology Introduction1. Introduction from IF signals, interference and noise prevention perfor- 1 mance have surpassed those of analog systems. In recent years, CDs, MDs, DVDs, and digital media have become the mainstream in the car AV market. 2.2 Goals of digitalization In terms of broadcast media, with terrestrial digital The following items were the goals in the develop- TV and audio broadcasting, and satellite broadcasting ment of this digital processing platform for radio: having begun in Japan, while overseas DAB (digital audio ①Improvements in performance (differentiation with broadcasting) is used mainly in Europe and SDARS (satel- other companies through software algorithms) lite digital audio radio service) and IBOC (in band on ・Reduction in noise (improvements in AM/FM noise channel) are used in the United States, digital broadcast- reduction performance, and FM multi-pass perfor- ing is expected to increase in the future. -
Next-Generation Photonic Transport Network Using Digital Signal Processing
Next-Generation Photonic Transport Network Using Digital Signal Processing Yasuhiko Aoki Hisao Nakashima Shoichiro Oda Paparao Palacharla Coherent optical-fiber transmission technology using digital signal processing is being actively researched and developed for use in transmitting high-speed signals of the 100-Gb/s class over long distances. It is expected that network capacity can be further expanded by operating a flexible photonic network having high spectral efficiency achieved by applying an optimal modulation format and signal processing algorithm depending on the transmission distance and required bit rate between transmit and receive nodes. A system that uses such adaptive modulation technology should be able to assign in real time a transmission path between a transmitter and receiver. Furthermore, in the research and development stage, optical transmission characteristics for each modulation format and signal processing algorithm to be used by the system should be evaluated under emulated quasi-field conditions. We first discuss how the use of transmitters and receivers supporting multiple modulation formats can affect network capacity. We then introduce an evaluation platform consisting of a coherent receiver based on a field programmable gate array (FPGA) and polarization mode dispersion/polarization dependent loss (PMD/PDL) emulators with a recirculating-loop experimental system. Finally, we report the results of using this platform to evaluate the transmission characteristics of 112-Gb/s dual-polarization, quadrature phase shift keying (DP-QPSK) signals by emulating the factors that degrade signal transmission in a real environment. 1. Introduction amplifiers—which is becoming a limiting factor In the field of optical communications in system capacity—can be efficiently used. -
Digital Signal Processing: Theory and Practice, Hardware and Software
AC 2009-959: DIGITAL SIGNAL PROCESSING: THEORY AND PRACTICE, HARDWARE AND SOFTWARE Wei PAN, Idaho State University Wei Pan is Assistant Professor and Director of VLSI Laboratory, Electrical Engineering Department, Idaho State University. She has several years of industrial experience including Siemens (project engineering/management.) Dr. Pan is an active member of ASEE and IEEE and serves on the membership committee of the IEEE Education Society. S. Hossein Mousavinezhad, Idaho State University S. Hossein Mousavinezhad is Professor and Chair, Electrical Engineering Department, Idaho State University. Dr. Mousavinezhad is active in ASEE and IEEE and is an ABET program evaluator. Hossein is the founding general chair of the IEEE International Conferences on Electro Information Technology. Kenyon Hart, Idaho State University Kenyon Hart is Specialist Engineer and Associate Lecturer, Electrical Engineering Department, Idaho State University, Pocatello, Idaho. Page 14.491.1 Page © American Society for Engineering Education, 2009 Digital Signal Processing, Theory/Practice, HW/SW Abstract Digital Signal Processing (DSP) is a course offered by many Electrical and Computer Engineering (ECE) programs. In our school we offer a senior-level, first-year graduate course with both lecture and laboratory sections. Our experience has shown that some students consider the subject matter to be too theoretical, relying heavily on mathematical concepts and abstraction. There are several visible applications of DSP including: cellular communication systems, digital image processing and biomedical signal processing. Authors have incorporated many examples utilizing software packages including MATLAB/MATHCAD in the course and also used classroom demonstrations to help students visualize some difficult (but important) concepts such as digital filters and their design, various signal transformations, convolution, difference equations modeling, signals/systems classifications and power spectral estimation as well as optimal filters. -
MIMO Technology in Wifi Systems
MIMO in WiFi Systems Rohit U. Nabar Smart Antenna Workshop Aug. 1, 2014 WiFi • Local area wireless technology that allows communication with the internet using 2.4 GHz or 5 GHz radio waves per IEEE 802.11 • Proliferation in the number of devices that use WiFi today: smartphones, tablets, digital cameras, video-game consoles, TVs, etc • Devices connect to the internet via wireless network access point (AP) Advantages • Allows convenient setup of local area networks without cabling – rapid network connection and expansion • Deployed in unlicensed spectrum – no regulatory approval required for individual deployment • Significant competition between vendors has driven costs lower • WiFi governed by a set of global standards (IEEE 802.11) – hardware compatible across geographical regions WiFi IC Shipment Growth 1.25x 15x Cumulative WiFi Devices in Use Data by Local Access The IEEE 802.11 Standards Family Standard Year Ratified Frequency Modulation Channel Max. Data Band Bandwidth Rate 802.11b 1999 2.4 GHz DSSS 22MHz 11 Mbps 802.11a 1999 5 GHz OFDM 20 MHz 54 Mbps 802.11g 2003 2.4 GHz OFDM 20 MHz 54 Mbps 802.11n 2009 2.4/5 GHz MIMO- 20,40 MHz 600 Mbps OFDM 802.11ac 2013 5 GHz MIMO- 20, 40, 80, 6.93 Gbps OFDM 160 MHz 802.11a/ac PHY Comparison 802.11a 802.11ac Modulation OFDM MIMO-OFDM Subcarrier spacing 312.5 KHz 312.5 KHz Symbol Duration 4 us (800 ns guard interval) 3.6 us (400 ns guard interval) FFT size 64 64(20 MHz)/512 (160 MHz) FEC BCC BCC or LDPC Coding rates 1/2, 2/3, 3/4 1/2, 2/3, 3/4, 5/6 QAM BPSK, QPSK, 16-,64-QAM BPSK, QPSK, 16-,64-,256- QAM Factors Driving the Data Rate Increase 6.93 Gbps QAM 802.11ac (1.3x) FEC rate (1.1x) MIMO (8x) 802.11a Bandwidth (8x) 54 Mbps 802.11 Medium Access Control (MAC) Contention MEDIUM BUSY DIFS PACKET Window • Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) • A wireless node that wants to transmit performs the following sequence 1. -
Multiple Access Techniques for 4G Mobile Wireless Networks Dr Rupesh Singh, Associate Professor & HOD ECE, HMRITM, New Delhi
International Journal of Engineering Research and Development e-ISSN: 2278-067X, p-ISSN: 2278-800X, www.ijerd.com Volume 5, Issue 11 (February 2013), PP. 86-94 Multiple Access Techniques For 4G Mobile Wireless Networks Dr Rupesh Singh, Associate Professor & HOD ECE, HMRITM, New Delhi Abstract:- A number of new technologies are being integrated by the telecommunications industry as it prepares for the next generation mobile services. One of the key changes incorporated in the multiple channel access techniques is the choice of Orthogonal Frequency Division Multiple Access (OFDMA) for the air interface. This paper presents a survey of various multiple channel access schemes for 4G networks and explains the importance of these schemes for the improvement of spectral efficiencies of digital radio links. The paper also discusses about the use of Multiple Input/Multiple Output (MIMO) techniques to improve signal reception and to combat the effects of multipath fading. A comparative performance analysis of different multiple access schemes such as Time Division Multiple Access (TDMA), FDMA, Code Division Multiple Access (CDMA) & Orthogonal Frequency Division Multiple Access (OFDMA) is made vis-à-vis design parameters to highlight the advantages and limitations of these schemes. Finally simulation results of implementing some access schemes in MATLAB are provided. I. INTRODUCTION 4G (also known as Beyond 3G), an abbreviation of Fourth-Generation, is used for describing the next complete evolution in wireless communications. A 4G system will be a complete replacement for current networks and will be able to provide a comprehensive and secure IP solution. Here, voice, data, and streamed multimedia can be given to users on an "Anytime, Anywhere" basis, and at much higher data rates than the previous generations [1], [2], [3]. -
Wi-Fi Data Rates, Channels and Capacity
WHITE PAPER Wi-Fi Data Rates, Channels and Capacity By Cees Links, GM of Qorvo Wireless Connectivity Business Unit Formerly CEO & Founder of GreenPeak Technologies Introduction Considerable confusion exists about the performance that Wi-Fi at 5 GHz and at 60 GHz (WiGig) actually deliver. The “Over the past 20 cause of this confusion stems mostly from the complexity of the interplay of the technical factors involved, as well as years, the IEEE the widely different Wi-Fi transmission environments – especially in indoor environments. Another reason is the 802.11 standard has not uncommon but facile assumption that faster is better. If you asked a road traffic expert whether faster meant provided increased better, he would tell you that faster driving means reduced road capacity. Data communications in a shared medium transmission speeds.” is not very different. Over the 20 years of its development, the IEEE 802.11 standard has provided for increasing levels of transmission speeds, but disappointing results in practical use have led to more emphasis on capacity. This paper attempts to clarify some of the complexities and to derive, given reasonable assumptions, what capacity consumers in dense residential settings can expect. December 2017 | Subject to change without notice. 1 of 8 www.qorvo.com WHITE PAPER: Wi-Fi Data Rates, Channels and Capacity IEEE 802.11ac and 802.11ax Transmission rates Marketing brochures usually give the maximum theoretically possible data rates that can only be realized in the lab under carefully controlled conditions. Table 1 lists the theoretical rates obtainable with the various protocol versions of the IEEE 802.11 standard. -
DATA COMMUNICATION Multiplexing
CS311: DATA COMMUNICATION Multiplexing by Dr. Manas Khatua Assistant Professor Dept. of CSE IIT Jodhpur E-mail: [email protected] Web: http://home.iitj.ac.in/~manaskhatua http://manaskhatua.github.io/ Outline of the Lecture • What is Multiplexing and why is it used ? • Basic concepts of Multiplexing • Types of Multiplexing: Frequency Division Multiplexing (FDM) Wavelength Division Multiplexing (WDM) Time Division Multiplexing (TDM) . Synchronous . Asynchronous Inverse TDM 24-09-2017 Dr. Manas Khatua 2 Introduction • To make efficient use of high-speed telecommunications lines, some form of multiplexing is used. • Multiplexing allows several transmission sources to share a larger transmission capacity. • Most individual data communicating devices typically require modest data rate, but the media usually has much higher bandwidth. • Two communicating stations do not utilize the full capacity of a data link. • The higher the data rate, the most cost effective is the transmission facility. 24-09-2017 Dr. Manas Khatua 3 Cont… • When the bandwidth of a medium is greater than individual signals to be transmitted through the channel, a medium can be shared by more than one channel of signals by using Multiplexing. • For efficiency, the channel capacity can be shared among a number of communicating stations. • Most common use of multiplexing is in long-haul communication using coaxial cable, microwave and optical fibre. 24-09-2017 Dr. Manas Khatua 4 Basic Concept • A device known as Multiplexer (MUX) combines ‘n’ channels for transmission through a single medium or link. • At the other end a De-multiplexer (DEMUX) is used to separate out the ‘n’ channels. 24-09-2017 Dr.