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The PCM non-uniform quantization method adopted in China and Europe is (a law 13 line pressure expansion), which is divided into (128) Quantizing levels, the non-uniform quantization method adopted by Japan and North America is (u-based Pressure Expansion ).
The zero-dispersion wavelength of the Z optical fiber is about (1.31) Um, and the minimum loss point is about (1.55) um.
China's long-distance No. 7 signaling network adopts the (3) level structure. The first level is (hstp), and the second level is (lstp ), level 3 is (signaling point sp ). The domestic network of large and medium-sized cities adopts the (2) level signaling network.
According to China's signaling network organization principles, each signaling link group should include at least (2) signaling links.
Signaling routes can be divided into normal routes and (roundabout routes)
In the No. 7 signaling method, OPC refers to (source signaling point code), DPC refers to (destination signaling point code), CIC refers to (circuit identification code), and SLC refers to (Signaling Link code ).
The basic function structure of the signaling method No. 7 is composed of (message transmission part (MTP) and (user part (up.
The signaling units of the No. 7 signaling method can be divided into (MSU), (lssu), and (fisu.
No. 7 signaling systems work in three modes: direct connection, quasi-direct connection, and full separation. The digital signaling link speed is (64) kbps.
1. the synchronous modes of the digital synchronization network can be divided into (quasi-synchronous), master-slave synchronization, and (mutual synchronization). The master-slave synchronization modes can also be divided into (master clock control synchronization mode) and (Level clock synchronization mode)
China's no. 7 signaling network signaling point code consists of (main signaling area code), (signaling area code) and (signaling point code.
Optical fiber can be divided into (Single-Mode Optical Fiber) and (Multi-Mode Optical Fiber) based on the total modulus of transmission)
Currently, China's mobile communication network (GSM) uses the (900 m) Hz and (1800 m) Hz frequencies.
China's digital mobile communication network (GSM) adopts a (3) structure, which is (tmsc1, tmsc2, and MSC)
In a digital mobile communication system, the interface is the interface between (MSC) and (BSC), the interface speed is (2 m) BPS, The abits interface is (BSC) and (BTS).
The seven layers in the OSI reference model are (physical layer), (data link layer), (network layer), (transport layer), (Session Layer), (presentation layer), and (Application Layer ).
TCP/IP refers to (Transmission Control Protocol), IP refers to the Internet protocol, IPX in IPX/SPX refers to (Internet Information Packet Exchange Protocol ), SPX refers to (sequence information exchange packet protocol ).
Each ts16 and ts31 on the 2048 kbit/s link on the v5.2 interface can be used as the physical C path. Any time slot not used as the C path can be used as the load path except ts0.
Because the integrated STP adopts the 2 Mbit/s interface, the clock level of the integrated STP should be determined by the level of the STP in the signaling network. The hstp should adopt the second-level a clock, if lstp is located in the C3 center, the second-level B clock should be used. If lstp is located in the Settlement Board, the third-level clock should be used.
The impact Grounding Resistance of the anti-lightning grounding device of telecommunication buildings should not exceed. Cables and metal pipes outside the building should be grounded before entering the building. lightning arresters should be added at the entrance when the cables and metal pipes outside the building are directly introduced into the room.
The switch data center must meet the national second-level fire prevention standards.
The conversion coefficient of each watt of electric energy into heat energy is 0.86.
The switch is a * timer to implement monitoring and forced release of traffic. The national standard stipulates that the waiting duration for a long time for the server to be detached is 10 s, and the waiting duration for a long time between the switches is 20 s, response Monitoring long-distance call 90 s.
National Standard SDH Equipment should be equipped with at least two synchronous clock input interface and one synchronous clock output interface, each interface should comply with the ITU-T recommendation g.703.
The maximum number of routes that a switch device can select for a destination board is 5.
The five color code lines used by the core pairs in the user cables of Huawei are pink orange green and blue gray.
For the fixed antenna of the base station, the VSWR of the wireless port should not exceed 1.5 Within the working frequency range.
The air physical channel of GSM is a physical entity with a bandwidth of 200 KHZ and a length of Ms.
The nominal value of net attenuation from mobile users to public communication network interfaces is 4.5dB 14, the user line traffic for non-ISDN services can be divided into two sets: (0.05-0.1) Erl/line and (0.1-0.15) Erl/line. The traffic volume of the trunk line can be (0.7) set Erl/line.
China's telecom network management system is divided into three levels: (National Center), (provincial center) and (domestic network center.
In SDH, the rate of STM-1 is (155.520 M) bps, the rate of STM-4 is (622.080 M) bps, and the rate of STM-16 is (2488.240 M) Bps.
The transmission mode of Signaling on multi-segment routing can be divided into (end-to-end) and (segment-by-segment forwarding). The No. 7 signaling method is (segment-by-segment forwarding ).
Currently, China's telephone network billing methods include (CAMA), (LAMA), and (PAMA,
According to the requirements of the C & C08 switch installation specifications, the room height (under the beam or air duct) shall not be less than (3.0) m.
The rack of the first rack of the C & C08 switch should be no less than (1.2-1.5) m from the wall, and the spacing between the front and rear of the two racks should generally be designed as (1.4-1.5) m, the minimum value shall not be less than (1.2) m; the distance between the side of the rack and the wall shall not be less than (0.8) m, and the distance from the back of the rack to the wall shall not be less than (1) M.
The DC input voltage range of the C & C08 switch is (-41 V ---57 V ).
C & C08 switch installation specifications require that the floor load should be no less than (450 ).
BITS provides two types of clock signals: (2 MHZ) and (2 Mbit.
The total transmission rate of the 2B + d isdn digital user line is (160 Kbps), and a frame has (20) bits.
The maximum transmission distance of a single network segment is (185) m, and the maximum transmission distance of a non-shielded twisted pair network cable is (100) M.
Communication equipment and power supply equipment (normally unelectrified metal part) in the IDC room, (grounding end of Protection Device of incoming cables), and (Metal Jacket of cables) shall be protected and grounded.
The microwave antenna and Its bracket on the roof should be connected to the nearest node (lightning-proof ground. The (upper end) of the antenna feeder and the entrance to the IDC must be grounded nearby.
The DC power supply ground wire of the power room must be introduced from the ground Collecting Line. The DC power supply ground wires of other data centers can also be introduced from (pooled online.
When the DC power supply grounding vertical lead length exceeds (30 meters), from (30 meters), each layer should be connected to the grounding terminal once.
In-board RF coaxial cabling cables (external conductors) and shielded cables (both ends of the shielding layer) shall maintain good electrical contact with the external surface of the metal casing of the connected equipment.
The cross-sectional area of protection Ground Wires of various types of communication equipment should be determined according to the maximum fault current value. Generally, (35-95) square millimeters (25-350A fault current) (multi-strand) copper wire should be selected.
The grounding resistance value of the integrated communication building should not be greater than (1) ohm.
A power supply system is composed of (AC Power Supply System), (DC power supply system), and (grounding system. (Centralized power supply), (distributed power supply), (hybrid power supply) are three typical system components.
The DC power supply system consists of (rectification equipment), (battery pack) and (DC power distribution equipment.
The full voltage drop of the 48 v dc discharge circuit should not be greater than (3.2) V.
The meaning of synchronization enables digital devices on the communication network to work on the same (average rate. The clock speed of the sending device is faster than that of the receiving device, which may cause (missed read) slide, and vice versa.
The synchronization of the synchronous network is the synchronization between the digital network (all device clocks. "Synchronization" includes two meanings: (bit timing) and (frame timing.
Synchronization Methods include (full synchronization), (full quasi-synchronization), and (hybrid synchronization.
Synchronization Methods include (master-slave synchronization) and (mutual synchronization ).
There are three transmission modes for the timing reference of the synchronization system: (PDH 2048 kbit/s leased line), (SDH STM-N line signal), (PDH 2048 kbit/s business circuit ).
The synchronous network has three interfaces: (2048 kHz), (2048 kbit/s), and (STM-N.