2012年软件水平网络工程师考试英语考前冲刺题（5）
Data communications equipment(DEC) (1) the serial data stream fromthe DTE and converts it to some form of(2) suitable oftransmission on voice grade lines. At the (3),the DCE performs thereverse function of convering the received analog signal to serialdigital data stream .The simplest form of DCE is a (4) or data set . At the transmit end, the modem can be considered a form of (5),whileat the receive end, it can be considered a form ofanalog todigital converter. The most common forms of modulation by modems are frequency shift keying(FSK),phase shift keying(PSK) ,and quadratureamplitude modulation(QAM). If the cables and signal levels used tointerconnect the DTE and DCE were left unregulated,the variationsgenerated would probably be proporation to the number ofmanufactures. Electronics Industries Association(EIA) ,anorganization of manufactuuers concerned with establishing industrystandards,have agreed on the RS-232C as the standard interfacebetween the DTE and the modem .This is a 25 pin cable pins havedesignated funtons and specified signal levels. (1) A. accepts B.sends C.delivers D.receives(2) A. digital signal B.analog signal C.light signalD.sound signal
(3) A. back end B.front end C.sending end D.receive end
(4) A. modem B.cpu C.demodulator D.modulator.
(5) A. host computer B.digital to analog converter
C. analog to digital converter D.secondaries
答案:
1:A,2:B,3:D,4:A,5:B
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