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Vision-Based Mobile Free-Space Optical Communications Kyle Cavorley, Wayne Chang, Jonathan Giordano, Taichi Hirao Advisor: Prof
Vision-Based Mobile Free-Space Optical Communications Kyle Cavorley, Wayne Chang, Jonathan Giordano, Taichi Hirao Advisor: Prof. Daut Abstract Methodology The implementation of a free-space optical (FSO) communication system capable of interfacing with moving receivers such as unmanned ground or aerial vehicles. Two way communication Inexpensive laser diodes are used to transmit data at rates of up to 1 Mbps. A computer vision and tracking system controls a pan-tilt platform for target Transmit side Receive side acquisition and tracking. Complex package components, suchs as a laser driver and photo receiver, are avoided when possible to study the design of low-level system components. A two way communication system is made possible utilizing a reflective optical chopper (ROC) at the receiver end. Motivations and Objectives Motivations: -High power efficiency with high throughput Fig. 2: Photodiode Amplifier and Comparator Circuit. Fig. 4: Laser Diode Driver Circuit. -Increased security Objectives: -Construct optical communication link capable of 1 Mbps at thirty feet range -Form and maintain two way optical communication channel -Build computer vision tracking system and platform Fig. 6: Boston Micromachines Reflective Optical Chopper (ROC); used in two-way communication Fig. 3: Output Response of photodiode Fig. 5: Schmitt Trigger Circuit. Only one end of the communication link amplifier/comparator. requires a visual tracking/laser targeting system. Results ❑ 2 Mhz signal successfully transmitted 14 feet using 5 mW 670 nm laser. ❑ AD8030 Op-amp used to amplify photodiode response signal from a range [60 mV, 1 V] to 5V before entering comparator that generates a TTL output. Fig. 1: Vision Based FSO Communication Block Diagram. -
Unit 7: Choosing Communication Channels
UNIT 7: CHOOSING COMMUNICATION CHANNELS Unit 7 highlights the importance of selecting an appropriate channel mix for a communication response and describes five categories of communication channels: mass media, mid media, print media, social and digital media and interpersonal communication (IPC). For each of these channels, advantages and disadvantages have been listed, as well as situations in which different channels may be used. Although this Unit has attempted to differentiate the channels and their uses for simplicity, there is recognition that channels frequently overlap and may be effective for achieving similar objectives. This is why the match between channel, audience and communication objective is important. This unit provides some tools to help assess available and functioning channels during an emergency, as well as those that are more appropriate for reaching specific audience segments. Once you have completed this unit, you will have the following tools to support the development of your SBCC response: • Worksheet 7.1: Assessing Available Communication Channels • Worksheet 7.2: Matching Communication Channels to Primary and Influencing Audiences What Is a Communication Channel? A communication channel is a medium or method used to deliver a message to the intended audience. A variety of communication channels exist, and examples include: • Mass media such as television, radio (including community radio) and newspapers • Mid media activities, also known as traditional or folk media such as participatory theater, public talks, announcements through megaphones and community-based surveillance • Print media, such as posters, flyers and leaflets • Social and digital media such as mobile phones, applications and social media • IPC, such as door-to-door visits, phone lines and discussion groups Different channels are appropriate for different audiences, and the choice of channel will depend on the audience being targeted, the messages being delivered and the context of the emergency. -
Modeling and Simulation of an Asynchronous Digital Subscriber Line Transceiver Data Transmission Subsystem
Modeling and Simulation of an Asynchronous Digital Subscriber Line Transceiver Data Transmission Subsystem Elmustafa Erwa ABSTRACT Recently, there has been an increase in demand for digital services provided over the public telephone line network. Asymmetric digital subscriber line (ADSL) transmit high bit rate data in the forward direction to the subscriber, and lower bit rate data in the reverse direction to the central office, both on a single copper telephone loop. I implemented a Synchronous Dataflow (SDF) model for an ADSL transceiver’s data transmission subsystem in LabVIEW. My implementation enables designers to simulate and optimize different ADSL transceiver designs. The overall implementation is compliant with the European Telecommunications Standards Institute’s ADSL specification. 1. INTRODUCTION With the emergence of the Internet as the cornerstone of communications in this age, the demand for high speed Internet access has only been increasing. Asymmetric digital subscriber lines (ADSL) is one of the technologies that provide high-speed Internet access in residences and offices [1]. It facilitates the use of normal telephone services, Integrated Services Digital Network (ISDN), and high-speed data transmission simultaneously. Hence, bandwidth-demanding technologies, such as video-conferencing and video-on-demand, are enabled over ordinary telephone lines. ADSL standards use discrete multi-tone (DMT) modulation [2]. DMT divides the effectively bandlimited communication channel into a larger number of orthogonal narrowband subchannels. This allows for maximizing the transmitted bit rate and adapting to changing line conditions. Designing ADSL systems is inherently complex. However, advances in the digital signal processor (DSP) technology allowed programmable DSP based solutions to replace application-specific integrated circuit based implementations. -
2 the Wireless Channel
CHAPTER 2 The wireless channel A good understanding of the wireless channel, its key physical parameters and the modeling issues, lays the foundation for the rest of the book. This is the goal of this chapter. A defining characteristic of the mobile wireless channel is the variations of the channel strength over time and over frequency. The variations can be roughly divided into two types (Figure 2.1): • Large-scale fading, due to path loss of signal as a function of distance and shadowing by large objects such as buildings and hills. This occurs as the mobile moves through a distance of the order of the cell size, and is typically frequency independent. • Small-scale fading, due to the constructive and destructive interference of the multiple signal paths between the transmitter and receiver. This occurs at the spatialscaleoftheorderofthecarrierwavelength,andisfrequencydependent. We will talk about both types of fading in this chapter, but with more emphasis on the latter. Large-scale fading is more relevant to issues such as cell-site planning. Small-scale multipath fading is more relevant to the design of reliable and efficient communication systems – the focus of this book. We start with the physical modeling of the wireless channel in terms of elec- tromagnetic waves. We then derive an input/output linear time-varying model for the channel, and define some important physical parameters. Finally, we introduce a few statistical models of the channel variation over time and over frequency. 2.1 Physical modeling for wireless channels Wireless channels operate through electromagnetic radiation from the trans- mitter to the receiver. -
Designing Asymmetric Digital Subscriber Line with Discrete Multitone Modulator
ISSN (Online) 2321-2004 IJIREEICE ISSN (Print) 2321-5526 International Journal of Innovative Research in Electrical, Electronics, Instrumentation and Control Engineering Vol. 7, Issue 11, November 2019 Designing Asymmetric Digital Subscriber Line with Discrete Multitone Modulator Attiq Ul Rehman1, Maninder Singh2 M. Tech., Student, ECE Department, Haryana Engineering College, Jagadhri, Haryana, India1 Assistant Professor, ECE Department, Haryana Engineering College, Jagadhri, Haryana, India2 Abstract: The objective of Digital Subscriber Line (DSL) is to propagate signal from the transmitter to the receiver over telephone lines. In communication industry Asymmetric Digital Subscriber Line (ADSL) is widely used because it can handle both phone services and internet access services at same time. As the communication industry develops, its main concern is to maximize the user handling capacity of communication systems. For this purpose, ADSL uses Discrete Multitone (DMT) modulator with QAM bank. But as the number of users increases the system complexity and interference also increases. The communication channel is not free from the effects of channel impairments such as noise, interference and fading. These channel impairments caused signal distortion and Signal to Ratio (SNR) degradation. One method that can be implemented to overcome this problem is by introducing channel coding. Channel encoding is applied by adding redundant bits to the transmitted data. The redundant bits increase raw data used in the link and therefore, increase the bandwidth requirement. So, if noise or fading occurred in the channel, some data may still be recovered at the receiver. While at the receiver, channel decoding is used to detect or correct errors that are introduced to the channel. -
The Wireless Communication Channel Objectives
9/9/2008 The Wireless Communication Channel muse Objectives • Understand fundamentals associated with free‐space propagation. • Define key sources of propagation effects both at the large‐ and small‐scales • Understand the key differences between a channel for a mobile communications application and one for a wireless sensor network muse 1 9/9/2008 Objectives (cont.) • Define basic diversity schemes to mitigate small‐scale effec ts • Synthesize these concepts to develop a link budget for a wireless sensor application which includes appropriate margins for large‐ and small‐scale pppgropagation effects muse Outline • Free‐space propagation • Large‐scale effects and models • Small‐scale effects and models • Mobile communication channels vs. wireless sensor network channels • Diversity schemes • Link budgets • Example Application: WSSW 2 9/9/2008 Free‐space propagation • Scenario Free-space propagation: 1 of 4 Relevant Equations • Friis Equation • EIRP Free-space propagation: 2 of 4 3 9/9/2008 Alternative Representations • PFD • Friis Equation in dBm Free-space propagation: 3 of 4 Issues • How useful is the free‐space scenario for most wilireless syst?tems? Free-space propagation: 4 of 4 4 9/9/2008 Outline • Free‐space propagation • Large‐scale effects and models • Small‐scale effects and models • Mobile communication channels vs. wireless sensor network channels • Diversity schemes • Link budgets • Example Application: WSSW Large‐scale effects • Reflection • Diffraction • Scattering Large-scale effects: 1 of 7 5 9/9/2008 Modeling Impact of Reflection • Plane‐Earth model Fig. Rappaport Large-scale effects: 2 of 7 Modeling Impact of Diffraction • Knife‐edge model Fig. Rappaport Large-scale effects: 3 of 7 6 9/9/2008 Modeling Impact of Scattering • Radar cross‐section model Large-scale effects: 4 of 7 Modeling Overall Impact • Log‐normal model • Log‐normal shadowing model Large-scale effects: 5 of 7 7 9/9/2008 Log‐log plot Large-scale effects: 6 of 7 Issues • How useful are large‐scale models when WSN lin ks are 10‐100m at bt?best? Fig. -
Telecommunication Through Broadband Services of Bsnl: a Bird’S Eye View
International Journal of Technical Research and Applications e-ISSN: 2320-8163, www.ijtra.com Volume 1, Issue 2 (may-june 2013), PP. 37-41 TELECOMMUNICATION THROUGH BROADBAND SERVICES OF BSNL: A BIRD’S EYE VIEW Dr Shilpi Verma Assistant Professor Deptt. of Library & information Science (School for Information Science & Technology) Babasaheb Bhimrao Ambedkar University (A Central University) Vidya Vihar, Rai-bareli Road Lucknow-226025 (UP) Abstract: In the cut throat competition every country telecommunication technologies are playing very vital want to be information equipped, the role. The consumers or users are demanding for faster and telecommunication is helping a lot in achieving the reliable bandwidth for purpose of e-commerce, same. Integrated communication is emerged as a boom videoconferencing, information retrieval and such other in communication world. The growth of data, applications. Broadband seems as a answer to these communication market and the networking questions. Broadband provides means of accessing technology trend has amplified the importance of technologies to bridge the customer & the service telecommunication in the field of information provider throughout the world. It basically provides high communication. Telecommunication has become one speed internet access, whereas the dial up connections of the very important part that is very essential to the was having their limitations and low speed. These socio-economic well being of any nation. The paper broadband services allow the user to send or receive video deals with concept of Broad band services of BSNL, or audio digital content and having real time features also. technology options for broadband services. Bharat It is able to provide interactive services. -
Short-Range Wireless Communication This Page Intentionally Left Blank Short-Range Wireless Communication
Short-range Wireless Communication This page intentionally left blank Short-range Wireless Communication Alan Bensky Newnes is an imprint of Elsevier The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, United Kingdom 50 Hampshire Street, 5th Floor, Cambridge, MA 02139, United States © 2019 Elsevier Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. -
Lecture 2 Physical Layer - Transmission Media
9/17/2013 DATA AND COMPUTER COMMUNICATIONS Lecture 2 Physical Layer - Transmission Media Mei Yang Based on Lecture slides by William Stallings 1 OVERVIEW transmission medium is the physical path between transmitter and receiver guided - wire / optical fiber unguided - wireless characteristics and quality determined by medium and signal in unguided media - bandwidth produced by the antenna is more important in guided media - medium is more important key concerns are data rate and distance 2 CpE400/ECG600 Spring 2013 1 9/17/2013 DESIGN FACTORS DETERMINING DATA RATE AND DISTANCE bandwidth • higher bandwidth gives higher data rate transmission impairments • impairments, such as attenuation, limit the distance interference • overlapping frequency bands can distort or wipe out a signal number of receivers • more receivers introduces more attenuation 3 ELECTROMAGNETIC SPECTRUM 4 CpE400/ECG600 Spring 2013 2 9/17/2013 TRANSMISSION CHARACTERISTICS OF GUIDED MEDIA Frequency Typical Typical Repeater Range Attenuation Delay Spacing Twisted pair 0 to 3.5 kHz 0.2 dB/km @ 50 µs/km 2 km (with 1 kHz loading) Twisted pairs 0 to 1 MHz 0.7 dB/km @ 5 µs/km 2 km (multi-pair 1 kHz cables) Coaxial cable 0 to 500 MHz 7 dB/km @ 4 µs/km 1 to 9 km 10 MHz Optical fiber 186 to 370 0.2 to 0.5 5 µs/km 40 km THz dB/km 5 TRANSMISSION CHARACTERISTICS OF GUIDED MEDIA 6 CpE400/ECG600 Spring 2013 3 9/17/2013 TWISTED PAIR Twisted pair is the least expensive and most widely used guided transmission medium. • consists of two insulated copper wires arranged in a regular spiral pattern • a wire pair acts as a single communication link • pairs are bundled together into a cable • most commonly used in the telephone network and for communications within buildings 7 TWISTED PAIR -TRANSMISSION CHARACTERISTICS analog digital limited: needs can use amplifiers either analog distance every 5km to or digital 6km signals needs a repeater bandwidth every 2km to (1MHz) susceptible to 3km interference and data rate (100MHz) noise 8 CpE400/ECG600 Spring 2013 4 9/17/2013 UNSHIELDED VS. -
Chapter 9: Communications Systems
GCE A level Electronics – Chapter 9: Communications systems Chapter 9: Communications systems Learning Objectives: At the end of this topic you will be able to: • recall that communication is the transfer of meaningful information from one location to another • recall the structure of a simple communication system consisting of: • information source • transmitter/encoder • transmission medium • amplifier/regenerator • receiver/decoder • information destination • recall and explain the relationship between: • bandwidth • data rate • information-carrying capacity • select and apply the equations: available bandwidth • NCH = channel bandwidth • maximum date rate = 2 × available bandwidth • explain the need to multiplex a number of signals onto one transmission medium and describe the principles of frequency and time division multiplexing • describe the role of filters in communication systems • use the decibel scale to express power gain in amplifiers and attenuation in transmission media • select and apply the equation: POUT • G = 10 log = dB 10 P IN • differentiate between noise and distortion • calculate the total gain in a communication system given the power gain or attenuation of its component parts • state what is meant by signal-to-noise ratio • select and apply the equations: PS VS • SNR = 10 log = = 20 log = dB 10 P 10 V N N • state what is meant by signal attenuation and describe the significance of signal attenuation (in dB) for the signal-to-noise ratio 282 © WJEC CBAC Ltd 2018 GCE A level Electronics – Chapter 9: Communications systems Introduction to information transfer Communication is defined as the transfer of meaningful information from one location to another. Over time, many ways of communicating information have evolved, allowing us to transfer information both faster and over greater distances. -
Multi-User Signal and Spectra Co-Ordination for Digital Subscriber Lines
KATHOLIEKE UNIVERSITEIT LEUVEN FACULTEIT TOEGEPASTE WETENSCHAPPEN DEPARTEMENT ELEKTROTECHNIEK Kasteelpark Arenberg 10, 3001 Heverlee MULTI-USER SIGNAL AND SPECTRA CO-ORDINATION FOR DIGITAL SUBSCRIBER LINES Promotor: Proefschrift voorgedragen tot Prof. Dr. ir. M. Moonen het behalen van het doctoraat in de toegepaste wetenschappen door Raphael CENDRILLON December 2004 KATHOLIEKE UNIVERSITEIT LEUVEN FACULTEIT TOEGEPASTE WETENSCHAPPEN DEPARTEMENT ELEKTROTECHNIEK Kasteelpark Arenberg 10, 3001 Heverlee MULTI-USER SIGNAL AND SPECTRA CO-ORDINATION FOR DIGITAL SUBSCRIBER LINES Jury: Proefschrift voorgedragen tot Prof. Dr. ir. G. De Roeck, voorzitter het behalen van het doctoraat Prof. Dr. ir. M. Moonen, promotor in de toegepaste wetenschappen Prof. Dr. ir. G. Gielen door Prof. Dr. ir. S. McLaughlin (U. Edinburgh, U.K.) Prof. Dr. ir. B. Preneel Raphael CENDRILLON Prof. Dr. ir. L. Vandendorpe (U.C.L.) Prof. Dr. ir. J. Vandewalle Prof. Dr. ir. S. Vandewalle U.D.C. 621.391.827 December 2004 c Katholieke Universiteit Leuven - Faculteit Toegepaste Wetenschappen Arenbergkasteel, B-3001 Heverlee (Belgium) Alle rechten voorbehouden. Niets uit deze uitgave mag vermenigvuldigd en/of openbaar gemaakt worden door middel van druk, fotocopie, microfilm, elektron- isch of op welke andere wijze ook zonder voorafgaande schriftelijke toestemming van de uitgever. All rights reserved. No part of the publication may be reproduced in any form by print, photoprint, microfilm or any other means without written permission from the publisher. D/2004/7515/88 ISBN 90-5682-550-X Acknowledgement I would like to thank my family for all the support and love they have given me over the years. My parents have always believed in me and this taught me to believe in myself. -
Communications Channels (Based on Blahut's Digital Transmission Of
Communications Channels (Based on Blahut’s Digital Transmission of Information) The transfer of messages between individuals or between cells is an activity that is fundamental to all forms of life, and in biological systems, delicate mechanisms have evolved to support this message transfer. Each of these messages traverses an environment capable of producing various kinds of distortion in the message, but the message must be understood despite this distortion. Yet, the method of message transmission must not be so complex as to unduly exhaust the resources of the transmitter or the receiver. Man-made communication systems also transfer data through a noisy environment. This environment is called a communication channel. A very important channel is the one in which a message is represented by an electromagnetic wave that is sent to a receiver, where it appears contaminated by noise. The transmitted messages must be protected against distortion and noise in the channel. The first such communication systems protected their messages from the environment by the simple expedient of transmitting high power. Later, message design techniques were introduced that led to the development of far more sophisticated communication systems. Modern message design is the art of piecing together a number of waveform ideas to meet a set of requirements: generally, to transmit as many bits as is practical within the available power and bandwidth. It is by the performance at low transmitted power that one judges the quality of a digital communication system. The purpose of this course is to develop in a rigorous mathematical setting the modem waveform techniques for the digital transmission of information.