程控交换复习题SPC exchange review.docx

1、程控交换复习题SPC exchange review程控交换复习题1（SPC exchange review 1）SPC exchange reviewI. simple questionsChapter 11. What is a communication network? What are the three parts of it?It consists of user terminal equipment, transmission equipment and switching equipment. It is completed by the exchange device, s

2、o that any user in the network can communicate with other users.2, realize the three elements of communicationTerminal, transmission and switching.3. What is a telephone exchange?Telephone switching is the most basic switching service in telecommunication. It refers to the information of any calling

3、 user, which can be sent to any desired or more called users through the switching nodes in the communication network.4. What are the 2 types of signals transmitted in a communication network?Analog signals and digital signals5, analog switches basic working principle?The switching function of the n

4、etwork is accomplished by the cross contact matrix, and the control part of the switch controls the disconnection and closing of the nodes in the control matrix so as to complete the connection of the input line and the output line.6, the basic working principle of digital switches?In digital switch

5、es, the transmission of the message channel is the pulse code modulation (PCM) signal, and the switching network adopts the digital switching network DSN. Digital switches generally refers to digital program-controlled switches, the switching network used mainly by the electronic switch array compos

6、ed of space division and time division switching network, composed of memory circuit switching network, are exchanged for space and time division.7. Classification of switching technologies(1) analog transmission and digital switching in the form of transmission signals.(2) according to the access c

7、ontrol method: control exchange and exchange program.(3) divided into circuit switching and packet switching in the form of transmission channel occupancy.(4) according to the transmission bandwidth: narrowband switching and broadband switching.8, what is the difference between circuit switching and

8、 packet switching?Circuit switching is a kind of real-time exchange. The user establishes the connection by calling, and the switching system allocates some bandwidth to both sides of the communication. When the communication is finished, the resource is released and the connection is removed.The st

9、ore and forward packet switching principle , the user information will be divided into several groups (packet) exchange and transmission, each packet contains a packet header information and domain 2 parts, packet switching node routing according to the routing information of the packet header, to c

10、omplete the exchange and transfer.9, what are the 2 forms of packet switching? What is their principle?Packet switching consists of 2 forms of virtual circuit and datagram.Each virtual circuit service through the call packet establishing a logical connection (virtual circuit), packet delivery servic

11、e to all in the virtual circuit establishment, each packet is not exclusive to the physical line, but still is the exchange of virtual circuit connection oriented. The datagram is oriented exchange connection, wherein each packet header to carry with the routing information, exchange nodes exchange

12、and transfer through the analysis of each routing information packet header, all packets of the same service may be along different paths to reach the end point.10, what are the 3 types of subscriber line signaling?User status signaling (monitoring signal), selective signaling (address signaling), s

13、ignaling to the subscriber.11, when the users phone is off the hook, the DC loop resistance users about 1.8K. When the user is on the hang state, the resistance between the users lines is greater than 20k.12, what are the 4 user status signaling?(1) (caller offhook) take breath;(2) response (called

14、user hook);(3) forward disconnect (calling subscriber hang up);(4) backward stitches (called subscriber).13. List the signal tones issued by the 3 switches to the user:Busy tone, dial tone, ring back tone.14, there are 2 sources of signal tone frequency: 450Hz and 950Hz.15. Chinas No. 1 signaling is

15、 divided into line signaling and register signaling.16, China line 1 signaling can be divided into DC line signaling, in band single frequency line signaling and digital line signaling.17, in line signaling, what are the provisions of the compulsory release?GB hook long dial: 10s, waiting for a long

16、 time, long waiting for a long time without dialing 20s, response monitoring long-distance call 90s.18, in the 30/32 road PCM system, each complex frame has 16 frames. Each frame has 32 time slots, 30 time slots transmit voice signals, the TS0 slot transmits frame synchronization signals, and the TS

17、16 slot transmits the line signaling of the speech channel.19, according to ITU recommendations, PCM code sampling frequency is 8000HZ, PCM base group multiplexing rate is 2.048Mb/s.20, NO.7 signaling system uses the function of modular structure, which mainly include 3 parts?The message passing sec

18、tion (MTP), the signaling connection control section (SCCP), and the user part (up).21, what are the three functional levels of the messaging part?Signaling data link function (MTP1), signaling link function (MTP2), signaling network function (MTP3).22, NO.What are the three signaling cell formats f

19、or the 7 signaling?The message signaling unit (MSU), the link state signaling unit (LSSU) and the fill signaling unit (FISU).What are the three parts of the 23 and NO.7 signaling networks?Signaling point SP, signaling transfer point STP, signaling link.24, what are the three levels of the NO.7 signa

20、ling network in China?Adopt 3 levels of structure: HSTP (Advanced), LSTP (lower level) and SP (signaling point).25. The transmission rate of digital signaling data link is 64Kb/s, and the transmission rate of analog signaling data link is 4.8Kb/s.26. The starting and ending flags used by the signali

21、ng unit delimitation are as follows: 01111110.27. Design the basic signaling process between 2 local telephone stations using China No. 1 signaling for call connection.28. Design the signaling process of the A switching board user calling the B switching office users local call connection with CCITT

22、7 signaling.Second chaptersWhat are the 2 parts of the 1 and T wiring devices? What are its main functions?The T connection is composed of a voice memory and control memory is composed of two parts, its function is to complete the exchange of information with the time slot interchange, a bus in diff

23、erent time slots, that is a line in a time division multiplexing time slot information exchange to another time slot.2, S type wiring device working principle?The S type connector consists of M * n crosspoint matrix and control memory. There is an intersection point J between each incoming line I an

24、d the outgoing Kij. When an intersection is connected under the control memory control, the corresponding input line can be connected with the corresponding line.3, homework P54, 16, 17, 18, 19 questions.Third chapters1, what are the 4 parts of the hardware part of the program controlled switch?Mess

25、age section, control section, operation system and maintenance section.2 、 the main function of analog user circuitFeeding, overvoltage protection, ringing control, monitoring, coding and decoding, filtering, mixing circuits, testing.3 、 feeding to the user phone is powered by the DC power supply of

26、 -48V.4, the user hub usually with 120 users for 1 groups, outgoing line for 4 sets of PCM line.5, when generating a signal tone, how many units of 500MHz tone does the 450MHZ need, and how many units of ROM memory are needed for the ROM?;6, the program-controlled switch control system can generally

27、 be divided into which three levels?The first level is the telephone peripheral control level.Level second is the call processing control level.Level third is the maintenance test level.7. What are the three modes of work in a dual processor architecture?Synchronous duplex operation, traffic sharing

28、, work mode and main / standby mode.8. Briefly describe the working principle of the main / standby modeTwo processors in this way, one for the main and the other for the standby. When the main machine fails, the standby machine will replace the main machine. There are two standby modes, namely cold

29、 standby and hot standby.Fourth chapters1, what are the 3 types of SPC switching systems?System data, office data, and user data.2, call handling 8 processes?1) calling hook, 2) dial tone, 3) receiving the number 4, number 5) through analysis), called 6), ringing, 7) called response and call, 8) end

30、 up3, user answers identification scanning cycle 200ms, dial pulse recognition scan cycle is 8ms, interval identification scanning cycle was 96ms.4, assuming that the user base for 32 users, using 8086 assembly or C language design group processing, pick, hang program.5. Design the bit interval iden

31、tification program in 8086 assembler or C language.Fifth chapters1. The mobile communication system is usually composed of mobile station (MS), base station (BS) and mobile switching center (MSC)2, the main functions of the base station:It is responsible for radio frequency signal transmission, rece

32、ption and wireless signal access to the MSC, and also has channel distribution, signaling conversion, wireless cell management and other control functions, usually a BS control of a wireless cell.3 、 the main function of mobile switching centerThe completion of this MSC control of mobile users in the region of communication control and management, including all types of mobile call control; through a standard interface connected with the base station (BS) and other MSC, switching, roaming and billing