Ea01 Rádiószolgálatok - FNFT A rádió összeköttetések és vezetékes összeköttetések összehasonlítása Rádiórendszerek típusai

Critical Attributes of Telecommunications Systems Speed – Ability to transmit information in real-time – Electronic transmission: faster than transportation Coverage – Beyond regional: national and international in scale Cost – 1866: 20 word telegram cost $100 (4 months wages) Security – Transmitted information as knowledge, news, secrets – Always an element of government oversight and control

ie. 2. század - Polybios Oszlopszám: 2Sorszám: 5 Fáklyatávíró - nappal max. 1 km - 8 betű/min - 24 betű  ld(24)=4.59 bit *8=36,7 bit/min = bit/sec

Claude Chappe (1793) 1852-ben már 4800 km hálózat 12-25km ismétlőállomás távolság 500km/h adattovábbítási seb. 92szimbólum Betűk, vezérlő szimbólumok, kódtábla azonosítók 2-3 szimb./min 6 szimb./min Párizs - Lille : 2 min

Lord George MURRAY (1795) 6 bites kódszavak  64 szimbólum Betűk, vezérlő szimbólumok 6 szimb./min London - Plymouth : 17 min 50 szimbólum  25 min 20 s 0.2 bit/sec

Forráskódolás "H.M.S. ROYAL SOVEREIGN ANCHORED AT SPITHEAD YESTERDAY SAILING FOR PLYMOUTH TOMORROW" (70 Zeichen) "RSOV ANCHOR SPITD YESDA SAIL PLYTH TMRO" (33 Zeichen).

Origins 1793, Revolutionary France – Aerial Telegraph, invented by Claude Chappe – Extensive network throughout France 1840s, Samuel F. B. Morse – Coded transmission via electronic means – Rapidly spread throughout US and Europe – International Telegraph Union (ITU) formed in 1865

Submarine Telegraphy: High Tech of the late 19th Century 1850: Dover-to-Calais, first submarine line 1858: First transatlantic cable – Breaks after 3 months! – President Buchanan & Queen Victoria exchange telegrams 1866: Relaid with higher quality cable – Development of cable materials, technology of laying, repair Typical “Performance”: – 1870: London to Bombay in 4 minutes, 22 seconds – 1901: London to British Guiana, 22 minutes – 1924: Telegram around the world in 80 seconds!

Radio Telegraphy (also know as “Wireless”) Radio technology – Communicate with ships and other moving vehicles – Messages sprayed into the “ether” crossing natl boundaries – Downfall of the nationally supported monopolistic telegraph Companies 1896: Guglielmo Marconi – First demonstration of wireless telegraphy – Built on work of Maxwell and Hertz to send and receive Morse Code – Based on long wave (>> 1 km), spark transmitter technology, requiring very large, high power transmitters – First used by British Army and Navy in the Boer War – 1899: Reported to shore America’s Cup yacht races

Wireless 1907: Commercial Trans-Atlantic Wireless Service – Huge ground stations: 30 x 100m antenna masts – Beginning of the end for cable-based telegraphy WW I: Rapid development of communications intelligence, intercept technology, cryptography 1920: Marconi discovers shortwave (<100 m) radio – Longwave follow contour of land » Very high transmit power, 200 KW+ – Shortwaves reflect, refract, and absorb, like light » Bounce off ionosphere » Higher frequencies made possible by vacuum tube (1906) » Cheaper, smaller, better quality transmitters

Other Important Dates 1915: Wireless voice transmission NY to SF 1920: First commercial radio broadcast (Pittsburgh) 1921: Police car dispatch radios, Detroit 1935: First telephone call around the world WW II: Rapid development of radio technology 1974: FCC allocates 40 MHz for cellular telephony 1982: European GSM and Inmarsat established 1984: Breakup of AT&T 1984: Initial deployment of AMPS cellular system

Rádiószolgálatok (WARC = World Administrative Radio Conference) ben WARC-77 műholdas TV műsorszóró szolgálatok bevezetésére teremtették meg a feltételeket 1992-ben WARC-92 személyi rádió frekvencia sávjának kijelölése

Rádiószolgálatok a.) Műsorszóró szolgálatok (Broadcast Services) b.) Állandóhelyű szolgálatok (Fixed Services) c.) Mozgó szolgálatok (Mobile Services) d.) Műholdas szolgálatok ( Satellite Services) e.) Hiteles frekvencia és órajel szolgálatok (Standard Frequency and Time Signals Services) f.) Rádiónavigációs szolgálatok (Radio Navigation Services) g.) Rádiólokációs szolgálatok (Radio Location Services) h.) Rádiócsillagászati szolgálatok (Radio Astronomy Services) i.) Amatőr szolgálatok (Amateur Services) j.) Ipari, tudományos és orvosi szolgálatok (ISM = Industrial, Scientific and Medical Services).

Spectrum management

GHz band allocation

FNFT – Frequency allocation table

Wireless Communication Tied to electromagnetic radio transmission radio transmission terrestrial orbital (satellite) point-to-point broadcast radio equatorial orbit non-equatorial orbit cellular non-cellular Principles: – Propagation and reception of electromagnetic waves – Modulation methods and their properties – Multiplex methods