2011-12-1自考专业英语单项选择2

1 自考专业英语单项选择自考专业英语单项选择 Part 1 1 Digital transmission provides a powerful method for noisy environment A overcome B get C getting D overcoming 2 The fundamental problem encountered by all serial data transmission system is how to split the incoming data stream individual units A at B into C from D on 3 A LAN is a data communication system allows a number of independent computers to communicate with each other A which B what C who D it 4 you need to know is that you can exchange message with other computers the Internet A What in B That on C That in D What on 5 Synchronous muleiplexing is the key cost and flexible tele cmmunication networking A for B in C to D with 6 Each nework is only capable of transporing one information type for it was intentionally designed A that B which C as D over 7 Each network is only capable of transporing one information type for it was intentionally designed A that B which C as D over 8 Timing signals from the interface assembly at the transmitter are the data modem to synchronize the computer and the data set A applied B applied to C applied in D application of 9 This is necessary the physical limitation of personal size radio equipment which uses with only 0dB gain A because of B because C which D that 10 Computer data are transported in the public domain by a packed switched data network based on X 25 protocol The word transported may be replaced by A carried B transmitted C received D got 11 It is growing so quickly nobody can say how many uses now On the Network A that exactly B that exact C whhat exactly D as to exactly 12 A signal frame in the serial signal stream can be represented a 2 dimensional map A at B in C by D with 13 Any communication system which can customers means to communicate from any place at any time time and at any distance gives social and economic advantages A provide with as B provide with C provide with in D provide as 14 Subscribers connect connect directly to an end office which must perform functions a PBX A the same such B the same with C same as D the same as 15 With circuit switching there is always an initial connection cost incurred in the circuit A making up B making C setting up D set up 16 Since the start and stop bits are different voltage levels it is easy to tell where valid character A begin B begins C start D begin to start 17 If sure a lot of issues will have to be resolved in coming months rather in coming years A then B that C than D thus 2 18 In the early days esch computer had its own equipment and software for A manufacturer networking B manufacturer networked C hardware networking D maker hardware 19 Many observers believe that national telephone systems will eventually handle video bandwidths by using fiber optics A upgraded to B be upgraded to C be upgrade to D be upgrading to 20 Such a signal meant that the person concerned had to call the switchboard operator immediately for instructions from telephone A the closest B closest C a closest D the closer 21 The operation of a communication network needs to be complemented by a messaging system which can offer additional facilities in the case of sophisticated network when the wired and mobile telephone network do not cover a whole territory The word is the best fit for sophisticated A common B simple C complex D similar 22 This results in an increasing demand for both multifunctional terminals as well flexible access to a universal network A to B in C on D as 23 The ISDN concept the mid 60s as a part of the progressive application of digital technology in public switch telephone network A born in B was born in C is born in D born at 24 The technological progress in the miniaturization of electronic circuitry in the early 1950s resulted the explosion of many new types of paging systems using wireless transmission A from B with C by D in 25 The routing algorithm is driven by seven or ten digit telephone number which identifies a subscriber and the centers in its direct hierarchy A usually B automatically C eventually D uniquely 26 Two Ethernets for example would be linked with a bridge a gateway A differently from B other than C rather than D apart from Part 2 1 The MTSO is the of the cellular mobile system A important B service C key D heart 2 The Internet is the largest repository of information which can provide very very large A network services B network resources C network devices D network nodes 3 World wide wed WWW is a hypertext protocol and user A network node B network nodes C networked interface D networked node 4 For instance the original CATV networks did not allowed the transportation of POTS or the PSTN dods not transport TV signals Here POTS is A plain old telephone service B popular old telephone service C plain operational telephone set D public old telephone service 5 In GSM system cellular the allocated frequency band in different geographic A uses locations B use locations C reuses location D reuses locations 6 transfers information in short packets called cells with a fixed length of 48 bytes plus five header bytes 3 A TCP B IP C AXC D ATM 7 ADMs are generally available at the STM 1 and TM 4 interface rates and may add drop a variety of tributary signals i E 2 34 or 140 Mb s ADM is A Add Data Multiplexers B Any drop Multiplexers C Add drop Multiplexer D Add Drop Modem 8 The codec is then arranged to sequentially sample the value and code this value into 8 digit sequence A time B amplitude C current D voltage 9 ISDN requires two pre requisites the presence of a wide spread digital networl the presence of CCITT No 7 A information B message C signal D signalling 10 Optic fibers can transmit very high bandwidth information A single paired fiber can carry 5000 channels A audio B telephone C voice D TV 11 Approximately 5 of the SDH signal structure is allocated to supporting advanced procedures and practices A network management B network manage C network building D network operating 12 Data rates for installed fiber optic systems have recently moved into the gigabit per range A minute B hour C seconds D second 13 Advances in audio video and speech coding and compression algorithms and progress in VLSI technology influence the bit rate generated by a certain service and thus change the service requirements for the network The letter I in VLSI means A Integration B Inter office C Inter city D Information Systems 14 ATM Asynchronous Transfer Mode is both a and technique A multiplexer switch B multiplexing switching C multiplexing routing D multiplex switch office 15 If we consider binary transmission the complete information about a particular message will be obtained by simoly detecting the and of the pulse A 1 and 0 B presence and absence C present and absent D one and zero 16 By far the most popular serial interface between a computer and its CRT terminal the asynchronous serial interface CRT is A a section program B a kind of language C computer ring terminal D the displayer of a computer 17 Data signals are transmitted over various types of telephone A number B circuits C offices D companies 18 The codec is then arranged to sequentially the amplitude value and code this value into ehe 8 digit sequence A sample B amplify C increase D decrease 19 The term 30 channel multiplexer 2Mb s multiplexer multiplex and primary are all in common use but they all refer to the same equipment A 32 time slot B 32 times alots C 32 time slot D 32 timing slots 20 The ISDN concept was born in the mid 60s as a part of the progressive application of digital technology in A PSTN B PBX C PDH D PCH 4 21 In a typical binary system for example digits 0 and 1 are represented by two different pulse A bits B amplitudes C values D bit time 22 The cell site provides interface between the MSTO and the mobile units MTSO means A mobile telephone service office B mobile telecom switch office C mobile telephone switching operation D mobile telephone switching office 23 In message switching the transmission unit is well defined block of data called a A message B bit C bits D cell 24 Data rates for installed fiber optic systems have recently moved into the gigabit per range A minute B hour C second D a second 25 A synchronous network with the elements makes a significant contribution to achieving these aims and offers a number of important benefits A SDH B TDH C PDH D CCH 26 So far in the discussion we have assumed that each voice channel has a separate coder the unit that converts amplitude values to a set of pulses and the unit that performs the operation A sampling reversed B to be sampled reverse C sampled reversed D sampled reverse 27 When the transmitter wishes to send data it first places the line a space level for one element period This element is called the and has a duration of T seconds A start byte B starting byte C start bit D first bit 28 An ATM network can transport and switch voice data and A vision B visitor C video D variety 29 The coverage extends to one third of the Earth s surface with one and with three to five geostationary satellites a quasi global coverage is achieved with the exception of polar regions A satellite B trunk C system D modulation 30 In cellular mobile telephone system divides the allocated frequency band into maximun numbers of channels A SSB B DSB C AM D FM 31 Cell is necessary when the traffic demand on a cell has reached the top and the cell is then separated into a number of smaller areas A composing B reducing C splitting D combining 32 The length of ATM cell is bytes A 53 B 1024 C 32 D 48 33 When no information is being transmitted the line is in a n state A immune B static C idle D spare 34 Most likely you will use a attached to your telephone line to talk to the Internet A Modem B Codec C STB D CPU 35 The shape of a cell in a cellular system is always depicted as a A octagon B hexagon C triangle D quadrate 36 The transmitter then sends the character 1 bit at a time by placing each bit on the line for a du