DOCSLIB.ORG

Unit 1: the Question and History of the Solutions… What Do We Use Communication for ?

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Unit 1: the Question and History of the Solutions… What Do We Use Communication for ? EECS 122: Introduction to Communication Networks Unit 1: The question and history of the solutions… What do we use communication for ? • Exchanging Information !!! /Getting information… - Runners (marathon!), Flags, Mirrors…. Etc.. - E-mail, WWW… • Maintaining inter-human relations - Letters (of affection!) - Phone … - SMS, CHAT, SOCIAL NETWORKS…. • Entertainment - Passive Live Theater/Circus/Movies/Radio/TV/Videos (on demand?) - Active Games!!! – network games – virtual worlds AW: Unit 1 2 EE 122 Spring 2015 2 What to communicate: Information, data • Information - Facts, Concepts, Ideas Information - A Human – oriented term Facts, concepts, • Data (encapsulated in media) ideas, … - A formalized representation of facts, concepts, ideas - Example: text, speech, picture - A human interpretation of data, conferring meaning to data • In Engineering we are interested in Data - Capturing “information” in the form of Formalized data (recording videos, taking pictures, representation of recording voice) information - Delivering data quickly to proper persons in form of media with high fidelity and efficiency AW: Unit 1 3 EE 122 Spring 2015 How? Telecommunication • First solution: Couriers - Runners (a.k.a. the story of marathon). Horse courriers, e.t.c - The concept of Relay! • Telecommunication = moving information over long distances - Without moving a human.. - But to selected, intended partners… • But HOW to move quicker? - Using “life help” – pigeons... - Using “guided media” to carry the document containing data è - (e.g. the pneumatic post, see eg. https://about.usps.com/who-we- are/postal-history/pneumatic-tubes.pdf ) - Using SIGNALS, i.e. physical phenomena able to propagate with high speed: Light, electricity, radio waves… AW: Unit 1 4History of TelecommunicationEE 122 Spring 2015 4 AW: Unit 1 5 EE 122 Spring 2015 The early optical signals • Visual signals - Limited to the Line of sight (LOS) • Examples: - Mirrors, Smoke - Humans giving signs... signaling convention: seamen flags, n Hissed flags http://www.christinedemerchant.com/flag- alphabet.html n Flag semaphore, e.g. http://www.anbg.gov.au/flags/semaphore.html n The optical Telegraph • And, much , much later: the optical fiber transmission J AW: Unit 1 6 EE 122 Spring 2015 Optical Telegraph • Optical Telegraph (Chappe, 1793) - Need for fast information flow in time of French Revolution n Claude Chappe installed the first optical telegraph line in summer 1794 AW: Unit 1 7 EE 122 Spring 2015 7 Electricity made THE change… • Telegraph (Morse, 1837) - Digitally coded text information, hard copy option (see e.g http://morsecode.scphillips.com/morse2.html ) - Large distance covered with constant quality - Low speed, rather public than individual use • Telephone (Bell, 1876, many claims from others…) - Transmission of voice (analog information) - Analog (later digital! Information transmission) - Individual use, end-system (not person) addressed - Data transmission by telephone is possible - World’s largest unified technical system! • Broadcast Services (30ties in 20th Century) - Radio, TV AW: Unit 1 8 EE 122 Spring 2015 8 Telegraph (1) [Noll, op. cit)] • Diagram of Simplex Electromagnetic Telegraph n a) Single simplex link n b) Two simplex links cascaded by repeater AW: Unit 1 9 EE 122 Spring 2015 9 Telegraph (2) [Noll, op. cit)] • Simplified diagram of Morse's half-duplex telegraph AW: Unit 1 10 EE 122 Spring 2015 10 Telephones - The basic Idea (1) [Noll, op. cit)] Variable-resistance transmitter Bell's liquid transmitter AW: Unit 1 11 EE 122 Spring 2015 11 Telephones - The basic Idea (2) [Noll, op. cit)] Watson's electromagnetic receiver AW: Unit 1 12 EE 122 Spring 2015 12 Early Broadcasting… • Drummers, walking and announcing (acoustic) • Mr. Litfaß – 5. Dec. 1854 Berlin, Germany (visual!) • Much later: Megaphones… (Acoustic, now: rlectric amplification of the acoustic signal!) AW: Unit 1 13 EE 122 Spring 2015 13 Some fundamentals… before moving further • Non-Zero delay between sending and receiving of a given message… (propagation delay!) - The speed of light – the highest possible is c =300 000 km/s in vacuum!! - The speed of electricity and light in optical fiber is v = 2/3 c • A bounded amount of messages can be posted in a time unit... - Think in term of the speed of Morse´ing or typing… or… - Think in terms of the speed of your internet access…J • Loss/errors in data transmission è THIS ALL IS REALITY !!! AW: Unit 1 14 EE 122 Spring 2015 Realistic Transmission… • Propagation delay d: - Propagation speed v: - d = distance / v • Data rate r: How much SOT:Start of messages/sec or bits/second transmission can a sender transmit? - (EOT – SOT) = Data size / data rate EOT: End of Time • Error rate: What is the rate of transmission incorrect messages arriving at the receiver? Delay d - Corrupted messages are frequently deleted…… Distance AW: Unit 1 15 EE 122 Spring 2015 Transmission medium can store data • What happens during a transmission? Start of transmission - Bits propagate to the receiver - Sender keeps sending bits - First bit arrives after d seconds Delay d Time - In this time, sender has transmitted d*r bits - They are “stored in the wire” (or in the Air!) • d*r is the product of delay and data rate - Commonly called Example (transcontinental): bandwidth-delay product • Data rate 100 Mbit/s - Crucial network property • Delay 4000km/(2/3c) = 0.02 s • d*r = 2 Mbit (in the wire) AW: Unit 1 16 EE 122 Spring 2015 Challenges in using signals • The speed of the signal can hardly be influenced…# • The number of data block (groups of bits)/second which we can transmit, as well as the probability of them being in error can be influenced - This is issues of communications… (eg. EE121) - We will discuss these topics shortly to understand how we can use it …or suffer form them… AW: Unit 1 17 EE 122 Spring 2015 Just a line? [H.Karl, Paderborn] • Connecting many phones - the simple issue ? AW: Unit 1 18History of TelecommunicationEE 122 Spring 2015 18 Concepts: The Network, Switching • Choosing the recipient of your call… • It is NOT efficient to build a physically separate path for each pair of communicating end systems (left picture). • CONCEPT: The Network: There is a set of path sections (e.g. electrical cables) and switching points (right picture). • “End systems” vs.“switching elements” a.k.a routers/bridges NOTE THE SIMILARITY TO OTHER NETWORKS …. AW: Unit 1 19History of TelecommunicationEE 122 Spring 2015 19 Communication Networks…a lot of questions • How to move data to a desired destination ? - Path selection? • How to structure data? “Portions”? Flows? • Mixing streams of data in the switches …overload? Losses…variable delay? • Binding of communication in the end systems? Many, Many issues…. This is the main subject of THIS CLASS AW: Unit 1 20 EE 122 Spring 2015 Concepts: Names, Addresses, Routing… • Name: WHO (identifies the object) - Structured for simple reference by humans! - E.g. According to organizational structure? Mnemonics? • Address: WHERE TO FIND (the object) - Must be REACHABLE - The object can move (mobility) è change address … • Route: HOW TO GET THERE - Has to assure delivery. - It is nice, if the address structure helps.. (e.g. street blocks) ? How to find the Address of some object ? ? How to find the route ? AW: Unit 1 21 EE 122 Spring 2015 Some considerations • Which objects would one like to address - Humans? Devices? Processes? • An object might have many points of access - A building with entrance from 2 different streets? - A human has Phone, e-mail, post, … - A laptop with WLAN (university Network) and ATT cellular? • How can addresses be grouped to enhance routing ? - City – District - Street- house – apartment AW: Unit 1 22 EE 122 Spring 2015 Types of addresses • Unicast: A single destination • Multicast: Destination is a group (defined explicitly or implicitly – i.e. every entity knows if it belongs…) • Anycast: Whoever of the group members • Broadcast: everybody… AW: Unit 1 23 EE 122 Spring 2015 Computer Networks • User logged into a single computer (or a process started by this user!) can: - Access any of the machines and use its resources - Execute processes. - Cause moving data (e.g. files) • Some important gains - Resource utilization: processor cycles, printers, specialized programs. - The centralized management of programs and data (software versions, backups) - Increase of SYSTEM reliability (as whole!) • Sharing and exchanging DATA - collaborative activities (work, entertainment, …) AW: Unit 1 24History of TelecommunicationEE 122 Spring 2015 24 Computer Networks: Consecutive challenges • Challenge I: Interconnection of different computer/OS types • Challenge II: Transmission Speed/Transmission Distance/… - WAN - Wide Area Network n No limit in distance n Provides national and international connectivity - LAN - Local Area Network n Less than approx. 1 km in distance n Provides local connectivity typically within a building - And many more…. n Mobile Cellular Data Networks n BAN (Body Area Networks) n SAN (Storage Area Networks) n Desktop Area Networks… n Industrial Networks AW: Unit 1 25History of TelecommunicationEE 122 Spring 2015 25 Internet: Interoperability vs. Heterogeneity WAN MAN LAN Gateway See:The Brief History of the Internet AW: Unit 1 26History of TelecommunicationEE 122 Spring 2015 26 Recent tendencies • Challenge III: Multimedia Communication - Observation: The information is stored/exchanged in MEDIA n Voice, Video, Data… n Different requirements as for transmission!!! - Historically supported by different technologies
Load more

Recommended publications
  • Super Duper Semaphore Or, As We Like to Call It
    Super Duper Semaphore Or, as we like to call it ... Flag Texting! Hello Lieutenants ... You can have a whole lot of fun with just a couple of hand flags. Even if you don’t have actual flags, you can make your own using items found around your home, like tea towels, or even two smelly old socks tied to some sticks! As long as you’re having fun ... be inventive. What’s it all about? Well, believe it or not, a great way for ships near (in range of) each other or ships wanting to communicate to the land is to use ‘Flag Semaphore’. It’s a bit like sending a text message ... but with your arms. It has been used for hundreds of years on both land and sea (from the sea, red and yellow flags are used). The word semaphore is Greek for ‘Sign-bearer’ Here’s how it works… Each letter of the alphabet has its own arm position (plus a few extras that we will cover in later ranks). Once you can remember these, you can send loads of hidden messages to your friends and family. Check these out ... ABCDEFG HIJKLM NOPQR STUVWX YZ How cool is that? To send a message the ‘sender’ gets the attention of the ‘receiver’ by waving their arms (and flags) by their side in an up and down motion (imagine flapping your arms like a bird). Don’t worry if you make mistakes or the receiver translates your signals into silly words - we’ve had lots of fun practicing this, and it will take time to become a Super Signaller! Are you ready to send your message? One letter at a time? Remember to pause between each letter and a bit longer between words to accurately get your message through.
    [Show full text]
  • Eie312 Communications Principles
    EIE312 COMMUNICATIONS PRINCIPLES Outline: Principles of communications: 1. An elementary account of the types of transmission (Analogue signal transmission and digital signal transmission). Block diagram of a communication system. 2. Brief Historical development on communications: a. Telegraph b. Telephony c. Radio d. Satellite e. Data f. Optical and mobile communications g. Facsimile 3. The frequency Spectrum 4. Signals and vectors, orthogonal functions. 5. Fourier series, Fourier integral, signal spectrum, convolution, power and energy correlation. 6. Modulation, reasons for modulation, types of modulation. 7. Amplitude modulation systems: a. Comparison of amplitude modulation systems. b. Methods of generating and detecting AM, DBS and SSB signals. c. Vestigial sideband d. Frequency mixing and multiplexing, frequency division multiplexing e. Applications of AM systems. 8. Frequency modulation systems: 1 a. Instantaneous frequency, frequency deviation, modulation index, Bessel coefficients, significant sideband criteria b. Bandwidth of a sinusoidally modulated FM signal, power of an FM signal, direct and indirect FM generation, c. Various methods of FM demodulation, discriminator, phase-lock loop, limiter, pre- emphasis and de-emphasis, Stereophonic FM broadcasting 9. Noise waveforms and characteristics. Thermal noise, shot noise, noise figure and noise temperature. Cascade network, experimental determination of noise figure. Effects of noise on AM and FM systems. 10. Block diagram of a superheterodyne AM radio receiver, AM broadcast mixer, local oscillator design, intermodulation interference, adjacent channel interference, ganging, tracking error, intermediate frequency, automatic gain control (AGC), delay AGC, diode detector, volume control. 11. FM broadcast band and specification, Image frequency, block diagram of a FM radio receiver, limiter and ratio detectors, automatic frequency control, squelch circuit, FM mono and FM stereo receivers.
    [Show full text]
  • Chloé Quenum + Adrian Dan: Minimally Invasive 26.02 --- 26.3.2015
    Chloé Quenum + Adrian Dan: Minimally Invasive 26.02 --- 26.3.2015 opening / february 26, 2015 / 19:00h Galeria Nicodim Bucharest Cantacuzino Palace Nr. 141, Victoria Street 010 071 Bucharest, Sector 1 Romania The drudgery of creative professionalism. A mix---up in the wash. Your best black shirt now looks like the skin of an old bronze statue, weepy with corrosion. There’s that jacket that makes you look interesting. Some tchotchkes on the desk. The obsolete deftness with which you made emoticons, now quaint as shorthand, or flag semaphore. Hopping from capital---to---capital, the same sleek wooden angles backed by a different iconic skyline at the best hotel in . Thumbing through pictures of an old crush on your phone, some old notes from a previous “project” tucked away until they are of use again. Maybe it’s time for a new shelf, one that angles just so.... Of all the shelves being built in the world, surely there is one that is just right. Surely someone has thought of you. There’s always time to rearrange the furniture; the fettered sticks that make up letters and words; the rows of images that don’t make a story. Adrian Dan (born 1985 in Constanta, Romania) works and lives in Paris. Adrian graduated as MA (honors) in 2011 at Ecole Nationale Superieure des Beaux Arts (ENSBA) in Paris. He had solo exhibitions in Paris and Bucharest, participated in group exhibitions in Brussels, Bucharest and Paris and is currently one of six researchers in residence at Marfa, Texas. Chloe Quenum (born 1983 in Paris, France) works and lives in Paris.
    [Show full text]
  • Flags and Banners
    Flags and Banners A Wikipedia Compilation by Michael A. Linton Contents 1 Flag 1 1.1 History ................................................. 2 1.2 National flags ............................................. 4 1.2.1 Civil flags ........................................... 8 1.2.2 War flags ........................................... 8 1.2.3 International flags ....................................... 8 1.3 At sea ................................................. 8 1.4 Shapes and designs .......................................... 9 1.4.1 Vertical flags ......................................... 12 1.5 Religious flags ............................................. 13 1.6 Linguistic flags ............................................. 13 1.7 In sports ................................................ 16 1.8 Diplomatic flags ............................................ 18 1.9 In politics ............................................... 18 1.10 Vehicle flags .............................................. 18 1.11 Swimming flags ............................................ 19 1.12 Railway flags .............................................. 20 1.13 Flagpoles ............................................... 21 1.13.1 Record heights ........................................ 21 1.13.2 Design ............................................. 21 1.14 Hoisting the flag ............................................ 21 1.15 Flags and communication ....................................... 21 1.16 Flapping ................................................ 23 1.17 See also ...............................................
    [Show full text]
  • Index of Linguistic Items
    Cambridge University Press 978-1-108-42359-5 — The Cambridge Encyclopedia of the English Language 3rd Edition David Crystal Index More Information VI INDEX OF LINGUISTIC ITEMS A auto 322, 330, 493 classist 189 -eau(x) 213 auto- 138 c’mon 79 -ectomy 210 a indefinite article 234–5, 350 aye 346 co- 138 -ed form 208, 210, 216, 223, 224, 237, short vs long 327, 345, 371 cockroach 149 346, 350 verb particle 367 B colour 179 -ed vs t (verb ending) 216, 331, 493 a- 138, 335 contra- 138 -ee 210, 220 -a noun singular 212 /b-/, /-b/ (sound symbolism) 263 could 224 -een 358 noun plural 212 B/b 271, 280 counter- 138 -eer 210, 220 -a- (linking vowel) 139 babbling 483 cowboy 148 eh 319 A/a 271, 280 back of 331 crime 176 eh? 230, 362 AA (abbreviations) 131 bad 211 curate’s egg 437 elder/eldest 211 -able 210, 223 barely 230 cyber- 452 elfstedentocht 383 ableism 189 bastard 263 Elizabeth 158 -acea 210 be 224, 233, 237, 243, 367 D -elle 160 a crapella 498 inflected 21, 363 ’em 287 -ae (plural) 213 regional variation 342 /d-/, /-d/ (sound symbolism) 263 en- 138 after (aspectual) 358, 363 be- 138 D/d 271, 280–1 encyclop(a)edia 497 -age 210, 220 be about to 236 da 367 encyclopediathon 143 ageist 189 been 367 danfo 495 -ene 160 agri- 139 be going to 96, 236 dare 224 -en form 21, 210, 212, -aholic 139 Berks 97 data 213 346, 461 -aid 143, 191 best 211 daviely 352 Englexit 124 ain’t 319, 498 be to 236 De- 160 -er adjective base ending 211 aitch 359 better 211 de- 138 familiarity marker 141, 210 -al 210, 220, 223 between you and I 206, 215 demi- 138 noun ending
    [Show full text]
  • India's Supreme Court Gives Disputed Holy Site to Hindus
    RABIA ALAWWAL 13, 1441 AH SUNDAY, NOVEMBER 10, 2019 28 Pages Max 31º Min 16º 150 Fils Established 1961 ISSUE NO: 17980 The First Daily in the Arabian Gulf www.kuwaittimes.net Municipality allows camping Bloomberg files papers paving Iraq forces clear protest sites as Chelsea up to second as 2 on Kuwait Bay’s eastern bank 8 way for US presidential bid 24 leaders reach deal to end rallies 28 Tottenham falter again India’s supreme court gives disputed holy site to Hindus Hundreds of Indian Sikhs make historic pilgrimage to Pakistan NEW DELHI/AYODHYA/KARTARPUR: India’s Supreme Court yesterday awarded a bitterly contested religious site to Hindus, dealing a defeat to Muslims who also claim the land that has sparked some of the country’s bloodiest riots since independence. The ruling in the dispute between Hindu and Muslim groups paves the way for the construction of a Hindu temple on the site in the northern town of Ayodhya, a proposal long supported by Prime Minister Narendra Modi’s ruling Hindu-nationalist party. Yesterday’s judgment, which is likely to be viewed as a win for Modi’s Bharatiya Janata Party (BJP) and its backers, was criticized as unfair by a lawyer for the Muslim group involved in the case. However, the group’s leader said ultimately it would accept the ver- dict and called for peace between India’s majority Hindus and Muslims, who constitute 14 percent of its 1.3 billion people. In 1992, a Hindu mob destroyed the 16th-century Babri Mosque on the site, triggering riots in which about 2,000 people, most of them Muslims, were killed across the country.
    [Show full text]
  • Lesson Deck INTRODUCTION to FLAG SEMAPHORE 3, 4, & 5
    SEA SERVICE TRADITONS Lesson Deck INTRODUCTION TO FLAG SEMAPHORE 3, 4, & 5 Instructional Objective(s): • Students will be able to comprehend, interpret, and examine the meaning of Sea Ser- vice Semaphore Flags and participate in an interactive activity based upon their grade level. Common Core Standard(s): (Refer to your local state standards if not using Common Core) Materials: Sea Service Traditions worksheet, Semaphore Flags image provided by the Department of Navy Anticipatory Set: • Warm-Up – ( 5 mins) • Project or write the question on the board, “How would ships communicate to each other before the radio, internet, and telephone?” Call on volunteers to share their response. Once the class has developed a working response, share that today we are going to discuss Sea Service Semaphore flags. One method sailor’s on ships would use to communicate to each other is to use Semaphore flags. Semaphore is a method of communicating by holding the flags in certain positions to spell out the alphabet. Instructional Input: • New Information – ( 35 mins) • Hand out the classwork assignment titled: Sea Service Semaphore Flags • Ask volunteers to read the directions aloud and begin the activity. • Review for Understanding ( 5 mins) • After the students have completed the assignment, ask for volunteers to share their findings • with the class. Closure: (5 mins) • Ask the students to answer the following question aloud, “What did you learn from today’s activity?” Considerations: • Bloom’s Taxonomy, learning styles (visual, auditory, kinesthetic), multiple intelligences SEA SERVICE TRADITONS Lesson Deck INTRODUCTION TO FLAG SEMAPHORE 3, 4, & 5 Directions: Semaphore is a method of communicating by holding 2 flags in certain po- sitions to spell out the alphabet.
    [Show full text]
  • V·Index of Linguistic Items
    Cambridge University Press 978-0-521-82348-7 - The Cambridge Encyclopedia of: The English Language: Second Edition David Crystal Index More information V · INDEX OF LINGUISTIC ITEMS A back of 311 dice 201 -ex 201 heightist 177 /k-/, /-k / (sound bad 199 did 347 exist 231 hello 393 symbolism) 251 a indefinite article 222–3, barely 218 different(ly) from/to/than extra- 128 helpmate 139 Kate 153 330 bastard 251 194, 311, 451 herb 260 Kellogg 268 short vs long 307, 325, be 212, 221, 225, 231, 347 dis- 128 F heterosexist 177 Kinki 114 351 inflected 21, 343 div/divent 326 his (= its)65 knave 63 verb particle 347 regional variation 322 do 45, 65, 70, 212, 219, -/f/ (sound symbolism) history 136 a- 128, 315 be- 128 228, 326, 347, 418 251 -hood 198, 208 L -a noun singular 201 be about to 224 does 204–5, 326 F/f 259–60, 268 hopefully 194, 229 noun plural 201 been 347 -dom 198, 208 far 199 house 207 /l/ clear 245, 337, 343, -a- (linking vowel) 129 be going to 224 don’t 219 farther/farthest 199 how (exclamatory) 219 345 A/a 259, 268 best 199 dos 326 -fashion 211 hurting 314 dark 245, 345, 354 AA (abbreviations) 121 be to 224 do so 228 fattyist 177 hyper- 128, 429 sound symbolism 251 -able 198, 211 better 199 dot 429 fi 347 vocalized 327 ableism 177 between you and I 194, 203 dunno 275 -fix 455 I voiceless 335 -acea 198 bi- 128 fore- 128 L/l 261 -ae (plural) 201 bio- 129 E for ti 338 I (pronoun) 347 La- 150 after (aspectual) 338, 343 bloody 98, 173, 352 frae 329 vs me 203 larf 275 -age 198, 208 -body 210 e magic/silent 42, 200, -friendly 133 -i (plural)
    [Show full text]
  • Escape Room Document
    100th Anniversary of Ontario Council Virtual Escape Room Instructions and Answers Accessing the Escape Room and Getting Started Use the link provided on the GGCOC page to access the Virtual Escape Room homepage (Google Chrome on a desktop/laptop is recommended). Once you access the webpage, you will see a Google Form on the top and the escape room locks on the bottom. You can complete the puzzles on your own screen while working collaboratively with your group OR your Guider can share their screen while everyone works through the puzzles as a group. When you are ready to begin, press the NEXT button in the Google Form. Lock #1: Timeline Unscramble Ontario Council is celebrating 100 years of history this year! Learn about some major milestones that have occurred between 1910 and now. Click on the lock #1 at the bottom of the page to begin the activity. You will be prompted to make a copy of the Timeline Unscramble. Click this prompt to save a copy of the activity to your Google Drive. Please note that a Google account is required to download the Google Slides. To download the document as PowerPoint slides instead, click the link under the lock. Once loaded, click on File > Download > Microsoft PowerPoint. Once downloaded, open the file in PowerPoint. Instructions • The first slide includes images of 8 major milestones and 8 important years in Ontario Council’s history. • The images and years in the red boxes are in the correct order, but all the other images have been mixed up and need to be reordered.
    [Show full text]
  • Semaphore Worksheet
    SEMAPHORE WORKSHEET Semaphore History: Flag semaphore is a system for conveying information at a distance by means of visual signals with handheld flags, rods, disks, paddles, or occasionally bare or Dùng Morse trong sinh hoạt Phong Trào gloved hands invented by a Frenchman, Claude Chappe in 1793. - Trong sinh hoạt mật mã Semaphore được dùng liên Information is encoded by the position of the flags; it is read when the flag is in a lạc khi ở xa tầm tiếng nói; đặc biệt trong các Hành fixed position. Different letters are represented by holding flags or lights Trình Đức Tin trại. outstretched in different positions around a circle. Prior to 1793, Chappe had - Ðặc điểm của Semaphore là để luyện tinh thần đồng experimented with a number of telegraph designs along with his brother, but đội; cùng học, cùng chơi, cùng truyền tin. these proved less than successful. The semaphore telegraph that Chappe designed consisted of a large pivoted horizontal beam, with two smaller bars attached at the ends, looking rather like a person with outstretched hands holding signal flags. The position of the horizontal beam could be altered, as well as the angle of the indicator bars at the ends. Chappe had developed the semaphore system to be used in the French revolution, to transmit messages between Paris and Lille, which was near the war front. In August 1794, Chappe's semaphore system delivered a message to Paris of the capture of Conde-sur-l'Escaut from the Austrians, in less than an hour. This success led to more semaphore telegraph lines being built, radiating in a star pattern from Paris.
    [Show full text]
  • On the Subject of Odd One Out
    Keep Talking and Nobody Explodes Mod Odd One Out On the Subject of Odd One Out One of these things is not like the others! One of these things just doesn’t belong! There are six buttons on the module which may display a variety of things directly on the button or in the display whilst hovering over a button. Five of the buttons, referred to below as the “good buttons”, satisfy a specific property which is described in the table below. Press the button that doesn’t belong — the “odd one out” — to move on to the next stage. The current stage is indicated by LEDs at the top of the module. Once 5 stages have been completed, press the button that has had the correct answer a unique number of times to disarm the module. You may long-press any button to reset the module back to stage 1. Display set Instructions Depending on the color of the LED to the right of the display: Red LED: The good buttons form a sequence of letters with equal distance in the alphabet, wrapping around from Z back to A. Yellow LED: The good buttons, when read in reading order, form a five-letter English word that is encoded using Atbash cipher. In this cipher, A↔Z, B↔Y, C↔X, etc. Green LED: The good buttons, when read in reading order, form a five-letter English word that is encoded using ROT13. In this Letters cipher, A↔N, B↔O, C↔P, etc. Turquoise LED: The good buttons have letters whose Morse code begins with the same two symbols.
    [Show full text]
  • Continue Letter of the Latin Alphabet This Article Is About the Letter of the Alphabet
    D Continue Letter of the Latin alphabet This article is about the letter of the alphabet. For other purposes, see D (disambigation). For technical reasons, D redirects here. For D-sharp, see D♯ (disambigation). For technical reasons, :D redirects here. For the keyboard symbol, see the emoji list. This article needs additional quotes to verify. Please help improve this article by adding quotes to reliable sources. Non-sources of materials can be challenged and removed. Find sources: D - News newspaper book scientist JSTOR (December 2014) (Learn how and when to delete this template message) DD d (see Դ դᎠᏛደVariations ₫ Ꭰ Ƌ Without proper rendering support instead of Unicode characters youדدܕbelow) Using the Latin Script SystemAnfabetikWang OriginAltin languagePhonetic ɖ ⁿd ɗ use of position4Numerical value: 4HistoryDevelopment No δD dTime period --700 to presentdeundans - Ď ∂SistersД can see question marks, boxes or other symbols. For an introductory guide to IPA symbols, see Help:IPA. ISO BasicLatin Alphabet Bb Cc Dd Ee Ff Gg Hh Ii Jj Kk Ll Mm Nd Oo Pp q Rr Ss Uu Vv Ww Yy zz vte D or d is the fourth letter of the modern English alphabet and the basic Latin alphabet ISO. Its name is in English di (pronounced /ˈdiː/), plural dees. The history of the Egyptian hieroglyphic door, the fish of the Phoenician dalet of the Greek delta Etrusca D Roman D Semitic letter Dalet, may have developed from a logogram for fish or doors. There are many different Egyptian characters that could have inspired this. In Semitic, ancient Greek and Latin, the letter was a d/; in the Etruscan alphabet the letter was superfluous, but still preserved (see letter B).
    [Show full text]