Electronic Science Electronic Communication 33. Data Communication Data Communication
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ACU-M™ Improving In-Building Communications
Application Note: AN-2306-2 ACU-M™ Improving In-Building Communications Purpose This application note will describe methods in which the Raytheon’s ACU-M can be used to improve in-building communications. The application note will discuss permanent and temporary methods at which different devices can help increase the ability to transmit or receive land mobile radio communications from within a building, below-grade, or behind obstructions. Introduction Land mobile radios, whether used in vehicles or as handheld portables, are an important tool used everyday by first responders to make their jobs safer and more efficient. In the most part, these radio systems function as designed, and serve the end-user with reliable communications. However, when the duties of a first responder require them to enter a building, or operate below- grade during emergencies, the ability of their radios to communicate to the base, incident command or dispatcher may become an issue. One physical constraint of land mobile radio communications is its inability to transmit and receive radio waves through obstructions such as buildings or below-grade structures. The failure of a land mobile radio to transmit and receive communications from within a building or below-grade has cursed radio users since the beginning of land mobile radio communications (see Figure 1). Figure 1: Blockage or Absorption of Low-Power Handheld Radio Transmission Raytheon 5800 Departure Drive Raleigh, NC 27616 919.790.1011 © Raytheon Company. Data is subject to change. http://www.raytheon.com All Trademarks are the property of their respective owners. Application Note: AN-2306-2 Solutions Land mobile radios were first introduced to public safety, in the late 20’s, in the form of shortwave receivers mounted inside patrol vehicles. -
Rs-232 Rs-422 Rs-485
ConceptConcept ofof SerialSerial CommunicationCommunication AgendaAgenda Serial v.s. Parallel Simplex , Half Duplex , Full Duplex Communication RS-485 Advantage over RS-232 SerialSerial v.s.v.s. ParallelParallel Application: How to Measure the temperature in a long distance? Measuring with a DAC card: 1200 m Remote sensor Control room T/C wire T/C A/D noise Application: How to Measure the temperature in a long distance? Measuring with a remote I/O module: 1200 m Remote sensor Control room T/C Remote I/O Standard Serial Communication T/C signal, 4-20mA, 0-5V… Noise rejection (Differential signal) MostMost PopularPopular 33 typestypes ofof SerialSerial Comm.Comm. z Most commonly available Tx Rx Rx Tx z Simple wiring CTS RTS z Low cost RTS CTS RS-232 z Short length (40 ft) DTR DSR DSR DTR Bar code reader z Slow data rates GND GND z Subject to noise Tx+ z High data rates Tx- z Longer cable lengths (4000 ft) Rx+ Rx- RS-422 z Full-duplex GND z Noise rejection PLC z Multipoint application (Up to 32 units) z Low cost Data+ z Longer cable lengths (4000 ft) Data- RS-485 zNoise immunity GND zHalf-duplex PLC SerialSerial V.S.V.S. ParallelParallel CommunicationCommunication Serial Communication Transfer the data bit by bit Synchronous Data Transfer Bit Send Data Receive Data Parallel Communication Transfer the all data simultaneously Asynchronous Data Transfer Bit Bit Bit Bit Bit Bit Bit Bit Send Data Receive Data SimplexSimplex ,, HalfHalf DuplexDuplex ,, FullFull DuplexDuplex CommunicationCommunication SimplexSimplex CommunicationCommunication Simplex Communication : – Data in a simplex channel is always one way. -
Printf and Primitive Types
CS 241 Data Organization using C printf and Primitive Types Instructor: Joel Castellanos e-mail: [email protected] Web: http://cs.unm.edu/~joel/ Office: Farris Engineering Center Room 2110 8/29/2019 1 Read: Kernighan & Ritchie Read ◼ Due Thursday, Aug 22 1.1: Getting Started 1.2: Variables and Arithmetic Expressions 1.3: The For Statement 1.4: Symbolic Constants ◼ Due Tuesday, Aug 27 (first iclicker quiz) 1.5: Character Input and Output ◼ Due Thursday, Aug 29 1.6: Arrays 2 2 1 Quiz: Basic Syntax One of these things is not like the others. One of these things does not belong. Can you tell which thing is not like the others before the end of this quiz? a) int a = 40 * 2*(1 + 3); b) int b = (10 * 10 * 10) + 2 c) int c = (2 + 3) * (2 + 3); d) int d = 1/2 + 1/3 + 1/4 + 1/5 + 1/6; e) int e = 1/2 - 1/4 + 1/8 - 1/16; 3 3 printf function printf("Name %s, Num=%d, pi %10.2f", "bob", 123, 3.14 ); Output: Name bob, Num=123, pi 3.14 printf format specifiers: %s string (null terminated char array) %c single char %d signed decimal int %f float %10.2f float with at least 10 spaces, 2 decimal places. %lf double 4 4 2 printf function: %d //%d: format placeholder that prints an int as a // signed decimal number. #include <stdio.h> void main(void) { int x = 512; Output: printf("x=%d\n", x); x=512 printf("[%2d]\n", x); [512] printf("[%6d]\n", x); [ 512] printf("[%-6d]\n", x); [512 ] printf("[-%6d]\n", x); [- 512] } 5 5 printf function: %f #include <stdio.h> void main(void) { float x = 3.141592653589793238; double z = 3.141592653589793238; printf("x=%f\n", x); printf("z=%f\n", z); printf("x=%20.18f\n", x); printf("z=%20.18f\n", z); } x=3.141593 Output: z=3.141593 x=3.141592741012573242 6 z=3.141592653589793116 6 3 Significant Figures Using /usr/bin/gcc on moons.unm.edu, a float has 7 significant figures. -
The Compression Problem Computational Thinking in This Discussion, We Will Look at the Compression Problem
Squeezing Ten Pounds of Data in a Five Pound Sack - or - The Compression Problem Computational Thinking In this discussion, we will look at the compression problem. Along the way, we will see several examples of computational thinking: • representations allow the computer to store and work with letters, images, or music by representing them with a numeric code; • patterns or repeated strings in text can be used by a computer for compres- sion; • index tables allow us to replace a long idea with a short word or number; Reading assignment Read Chapter 7, pages 105{121, \9 Algorithms that Changed the Future". The Compression Problem for Traveling When you pack for a trip, you want to minimize the number of suitcases and bags you take, but maximize the things you can transport. Sometimes it takes several repackings, rolling and squashing and rearranging, before you are satisfied. The Compression Problem for File Storage Your computer hard disk has a limited amount of storage. The information in a single movie or song could easily fill up your entire computer memory. This doesn't happen because the information is compressed in several ways. The Compression Problem for Data Transmission Data must be transferred from one place to another, over networks with limited capacity. In North America, 70% of Internet traffic involves services that are streaming data, such as movies or music. When the local network is overloaded, a movie becomes unwatchable, music becomes noise, users are dissatisfied. Solving the compression problem with more capacity One solution to these problems is to increase capacity: Buy more suitcases or bigger ones. -
Ascii, Baudot, and the Radio Amateur
ASCII, BAUDOT AND THE RADIO AMATEUR George W. Henry, Jr. K9GWT Copyright © 1980by Hal Communications Corp., Urbana, Illinois HAL COMMUNICATIONS CORP. BOX365 ASCII, BAUDOT, AND THE RADIO AMATEUR The 1970's have brought a revolution to amateur radio RTTY equipment separate wire to and from the terminal device. Such codes are found in com and techniques, the latest being the addition of the ASCII computer code. mon use with computer and line printer devices. Radio amateurs in the Effective March 17, 1980, radio amateurs in the United States have been United States are currently authorized to use either the Baudot or ASCII authorized by the FCC to use the American Standard Code for Information serial asynchronous TTY codes. Interchange(ASCII) as well as the older "Baudot" code for RTTY com munications. This paper discusses the differences between the two codes, The Baudot TTY Code provides some definitions for RTTY terms, and examines the various inter facing standards used with ASCII and Baudot terminals. One of the first data codes used with mechanical printing machines uses a total of five data pulses to represent the alphabet, numerals, and symbols. Constructio11 of RTTY Codes This code is commonly called the Baudot or Murray telegraph code after the work done by these two pioneers. Although commonly called the Baudot Mark Ull s,.ce: code in the United States, a similar code is usually called the Murray code in other parts of the world and is formally defined as the International Newcomers to amateur radio RTTY soon discover a whole new set of terms, Telegraphic Alphabet No. -
A Look at Telegraph Codes
Compression, Correction, Confidentiality, and Comprehension: A Look at Telegraph Codes Steven M. Bellovin Columbia University [email protected] Abstract Telegraph codes are a more-or-less forgotten part of technological history. In their day, though, they were ubiquitous and sophisticated. They also laid the groundwork for many of today’s communications technologies, including encryption, compression, and error correction. Beyond that, reading them pro- vides a snapshot into culture. We look back, describing them in modern terms, and noting some of the tradeoffs considered. 1 Introduction Most cryptologists have heard of telegraph codes. Often, though, our knowledge is cursory. We’ve forgotten what we read in Kahn [9], and perhaps remember little more than the basic concept: a word, phrase, or sentence is represented by a single codeword. In fact, telegraph codes were far more sophisticated, and laid the groundwork for many later, fundamental advances. Looked at analytically, telegraph codes fulfilled four primary functions: compression, correction, confi- dentiality, and comprehension. Beyond that, they offer a window into the past: the phrases they can be used to represent give insight into daily lives of the time. This paper, based primarily on my own small collection of codebooks, illustrates some of these points. For typographical simplicity, I have written codewords LIKE THIS, while plaintext is written this way. 2 Compression Compression was the original goal of telegraph codes. Early trans-Atlantic telegrams were extremely expen- sive — $100 for twenty words in 1866 [8] — so brevity was very important. Early telegraph codes had two ancestors, codes for semaphore networks and naval signaling [9]. -
Letter Circular 45: Construction and Operation of a Simple
' «i -•aif -ISe • 1-b Publication of the Letter DEPARTMENT OF COM'lERCE Circular BUREAU OF STANDARDS LC 45 WASHINGTON, D. 0. CONSTRUCTION AND OPERATION OF A SIMPLE RAD IOTELEGP.APHI C CODE PRACTICE SET.* (Prepared at request of the States Relations Service, United States Department of Agriculture for use by Boys 1 and Girls 1 Radio Clubs.) Introduction This pamphlet describes apparatus which may be used for the pur- pose of learning the radio telegraph code. The apparatus is very easy to set up and operate. It is intended to be used at radio club meet- ing places or in places where a number of radio students are accustomed to assemble. Those who construct the simple radio receiving sets des- cribed in the first two pamphlets of this series will probably hear many signals which are in code. The Code Practice Set is therefore made a part of this series so shat the international Morse Code may be learned. The cost of the complete outfit will be about $5*70 or, if one constructs the telegraph key, she. cost will be reduced to about $3«b0 It is assumed that those who use this outfit have radio receiving sets and can bring their telephone receivers (“phones") to connect to the other apparatus. It is also assumed that it will not be necessary to purchase the table upon which the parts are mounted. It is desirable *This is the third of a series of pamphlets describing the construction of radio equipment. The two publications which nave been issued are Letter Receiving Circular 43 , "Construction and Opera-cion of a Very Simple Radio Equipment," and Letter Circular 44, "Construction and Operation of a Two- Circuit Radio Receiving Equipment with Crystal Detector." These describe the construction and operation of simple receiving sets. -
Restricted Radiotelephone Operator's
INDEPENDENT COMMUNICATIONS AUTHORITY OF SOUTH AFRICA RESTRICTED RADIOTELEPHONE OPERATOR’S EXAMINATION GUIDE (VHF, MF AND HF) June 2008 TABLE OF CONTENTS EXAMINATION PAYMENT INFORMATION ________________________________________ 3 BACKGROUND ______________________________________________________________ 4 COMMENTS _________________________________________________________________ 8 SYLLABUS FOR THE POSTMASTER GENERAL’S RESTRICTED CERTIFICATE __________ 8 EXAMINATION ARRANGEMENTS _______________________________________________ 9 IMPORTANT RADIOTELEPHONE FREQUENCIES __________________________________ 9 IMPORTANT VHF MARITIME FREQUENCIES ______________________________________ 9 RADIOTELEPHONE DISTRESS PROCEDURE _____________________________________ 9 RADIOTELEPHONE URGENCY ________________________________________________ 15 RADIOTELEPHONE SAFETY __________________________________________________ 16 MARINE TERMINOLOGY & MODES OF EMISSION ________________________________ 17 ALARM SIGNALS ____________________________________________________________ 18 EPIRBS, VERY IMPORTANT CHECKS ON EPIRBS ________________________________ 18 SART (SEARCH AND RESCUE RADAR TRANSPONDER) ___________________________ 19 NAVTEX RECEIVERS ________________________________________________________ 19 SATELLITE COMMUNICATIONS _______________________________________________ 19 RADIOTELEPHONE CALLING PROCEDURE _____________________________________ 20 TABLE OF CALLING AND ANSWERING FREQUENCIES ____________________________ 21 RADIOTELEGRAMS _________________________________________________________ -
Voice Radio Communications Guide for the Fire Service June 2016
U.S. Fire Administration Voice Radio Communications Guide for the Fire Service June 2016 U.S. Fire Administration Mission Statement We provide National leadership to foster a solid foundation for our fi re and emergency services stakeholders in prevention, preparedness, and response. This page intentionally left blank. Voice Radio Communications Guide for the Fire Service i Acknowledgment The U.S. Fire Administration (USFA) is committed to using all means possible for reducing the incidence of injuries and deaths to firefighters. One of these means is to partner with organizations that share this same admirable goal. One such organization is the International Association of Fire Fighters (IAFF). As a labor union, the IAFF has been deeply committed to improving the safety of its members and all firefighters as a whole. This is why the USFA was pleased to work with the IAFF through a partnership supported by the U.S. Department of Homeland Security (DHS), Science and Technology Directorate, First Responders Group, Office for Interoperability and Compatibility to develop this second edition of the “Voice Radio Communications Guide for the Fire Service.” The USFA gratefully acknowledges the following leaders of the IAFF for their willingness to partner on this project: General President Harold Schaitberger General Secretary-Treasurer Thomas Miller Assistant to the General President Occupational Health, Safety and Medicine Patrick Morrison International Association of Fire Fighters, AFL-CIO, CLC Division of Occupational Health, Safety and Medicine -
The Benefits of Computer Networks
قسم علوم الحاسوب | المرحلة الرابعة كلية الرافدين الجامعة د.اسيل خالد Introduction to Computer Network: Interconnected collection of autonomous computers. Tow computers are side to be interconnection if they are able to exchange information. Or: network is simply a collection of intercommunicating computers and peripherals possibly having access to remote hosts and other computer networks. A network consists of a set of computers: hosts, connected via a communication subnet. The word 'host' refers to an individual computer connected to the network, which can communicate with other hosts via the network. A Compute network should ensure: reliability of the data communication process security of the data performance by achieving higher throughput and smaller delay times The benefits of computer networks: We can summarize the benefits of computer networks as follow: 1. Resource sharing: the goal is to make all programs, equipment, and especially data available to anyone on the network without regard to physical location of the resource and the user. 2. High reliability: by having alternative sources of supply .for example, all files could be replicated on two or three machines, so if one of them is unavailable (due to a hardware failure. قسم علوم الحاسوب | المرحلة الرابعة كلية الرافدين الجامعة د.اسيل خالد 3. Saving money: small computers have a Mach better price/performance ratio than large ones. Mainframes (room-size computers) are roughly a factor of ten faster than personal computers, but they cost a thousand times more. 4. Scalability: is the ability to increase system performance gradually as the workload grows just by adding more processors. 5. -
Unit 1. Introduction to Data Communications and Networking
Unit 1. Introduction to data communications and networking 1 NETWORKING FUNDAMENTALS Unit Structure 1.0 Objectives 1.1 Introduction 1.2 Data & Information 1.3 Data Communication 1.3.1 Characteristics of Data Communication 1.3.2 Components of Data Communication 1.4 Data Representation 1.5 Data Flow 1.5.1. Simplex 1.52. Half Duplex 1.5.3. Full Duplex 1.6 Computer Network 1.6.1 Categories of a network 1.7 Protocol 1.7.1 Elements of a Protocol 1.8 Standards In Networking 1.8.1 Concept of Standard 1.8.2 Standard Organizations in field of Networking 1.0 OBJECTIVES: Introduce the readers to data communication and its fundamentals Define networks Define protocols Standards in networking 2 1.1 INTRODUCTION This chapter provides an introduction to Computer networks and covers fundamental topics like data, information to the definition of communication and computer networks. The main objective of data communication and networking is to enable seamless exchange of data between any two points in the world. This exchange of data takes place over a computer network. 1.2 DATA & INFORMATION Data refers to the raw facts that are collected while information refers to processed data that enables us to take decisions. Ex. When result of a particular test is declared it contains data of all students, when you find the marks you have scored you have the information that lets you know whether you have passed or failed. The word data refers to any information which is presented in a form that is agreed and accepted upon by is creators and users. -
Tutorial Introduction
Tutorial Introduction PURPOSE: • This tutorial describes concepts related to communication busses, including attributes, functions, and the different types of bus systems. The intent is to provide a baseline of knowledge related to the Freescale product line. OBJECTIVES: • Define basic terminology and concepts related to bus communication. • Describe bus operations and the different types of communication. • Identify the attributes of the main bus types. • Match a bus type to application requirements. • Describe Freescale’s portfolio of bus ICs. CONTENT: • 48 pages • 8 questions LEARNING TIME: •90 minutes This tutorial introduces concepts related to communication busses, including features, functions, and the different types of bus systems. We will examine the main bus types, identifying key attributes for each type. We will discuss how to prioritize bus attributes when selecting a bus for a specific application. Finally, we will introduce Freescale’s portfolio of bus ICs. Although there is no prerequisite for this tutorial, some experience with bus communication would be helpful. 1 Communication Bus • A communication bus, or simply bus, is a one- or two-wire media onto which electrical devices are connected at points on the bus for the purpose of communicating. • The DSI bus, in addition to providing the communication media, also provides operational power for the bus device. • The purpose of a bus is to minimize the wire necessary to pass data between two or more devices. Let’s begin by defining a communication bus. For the purpose of this training, a communication bus, or simply a bus, relates to a one- or two-wire media onto which electrical devices are connected at points on the bus for the purpose of communicating.