局域异步通信

44.14.2asynchronous4.31004-14-1waveformdiagram4.44-1+01010014-110ITUEIAIEEE2ASCIIEIAEIARS-232-CRS-232RS-422RS-232-15V+15V50RS-232character78RS-232serialparallelRS-232RS-23211RS-2320startbitRS-2321RS-232stopbit4-2RS-2327RS-2329RS-23215V1+15V0RS-232RS-232415+150-15idlestart1011010stopidle4-2RS-23216MARKSPACERS-232RS-232ASCIIRS-2324.511RS-2323001920033600baudrateRS-232960096005RS-232framingerrorRS-232ASCIIBREAKBREAKASCIIBREAK201BREAKBREAK4.6groundRS-232RS-232RS-232ASCIIfullduplextransmissionhalfduplextransmissionsimplextransmission417RS-232RS-23225DB-2525cleartosendRS-232threewirecircuit4-34-3RS-2324-32523327computerterminalequipmentCTEdataterminalequipmentDTE2233CTE23322-32-3nullmodem54.74-24-4RS-2324-44.8TRGTRG4-418bandwidthcyclespersecondHz4000Hz4000NyquistSamplingTheoremRS-232B2BKDD=2Blog2K4.9noise1948ClaudeShannonC=Blog21+S/NCBSNS/N10log10S/NdecibeldBS/N10020dBS/N100030dB4.1030dB3000HzC=3000log21+100030000bps4.11RS-232RS-232RS-2324.1EmileBaudotBaudot4.2bitASCIIRS-23227ASCII4.39600RS-2321000074.44000Hz44.5RS-232DB-254.625PCDB-9RS-232DB-94.7RS-2324.8RS-2325%4.9RS-2324.10RS-232419