This specification is formulated to make the engineering design and construction of cable television systems (hereinafter referred to as systems) technologically advanced, economically reasonable, safe and applicable, and ensure quality. This specification applies to the design, construction and acceptance of new, expanded and rebuilt projects of cable television systems with the following signal transmission methods. GB 50200-1994 Cable Television System Engineering Technical Specification GB50200-1994 Standard download decompression password: www.bzxz.net

Engineering construction standard full text information system
National Standard of the People's Republic of China
50200—94
Technical code for regunation of CATV systemGB
50200—94
1992—04-02
1992—10—01
State Bureau of Technical Supervision
Ministry of Construction of the People's Republic of China
Engineering construction standard full text information system
Jointly issued
Engineering construction standard full text information system
National Standard of the People's Republic of China
Technical code for regunation of CATV system systemGB50200-94
Editor department: Ministry of Radio, Film and Television of the People's Republic of ChinaApproval department: Ministry of Construction of the People's Republic of ChinaEffective date: November 1, 1994
Engineering Construction Standard Full Text Information System
Engineering Construction Standard Full Text Information System
Notice on the release of the national standard
"Cable TV System Engineering Technical Specification"Jianbiao [1994] No. 198
According to the requirements of the State Planning Commission's Jizong [1986] No. 450 and the Ministry of Construction's Jianbiao [1991] No. 727, the "Cable TV System Engineering Technical Specification" jointly formulated by the Ministry of Radio, Film and Television and relevant departments has been reviewed by relevant departments. The "Cable TV System 350200-94" is now approved as a mandatory national standard and will be implemented from November 1, 1994 Engineering Technical Specification" GB
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This standard is managed by the Ministry of Radio, Film and Television, and the specific interpretation and other work is the responsibility of Wuhan Radio and Television Bureau. The publication and distribution is organized by the Standard and Quota Research Institute of the Ministry of Construction. Ministry of Construction of the People's Republic of China
March 11, 1994
Engineering Construction Standard Full Text Information System
Engineering Construction Standard Full Text Information System
Engineering Design of Systems
General Provisions
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Basic Mode and Main Technical Indicators of the System Distribution Receiving Antenna
Trunk Transmission
Distribution Network
Front-end Machine Room and Self-operated Program Station
Component Installation and Line Laying
Lightning Protection, Grounding and Safety Protection Protection
Engineering construction of the system
General provisions
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Receiving antenna
Front-end machine room
Trunk line erection
Branch line and user line
Lightning protection, grounding and safety protection
System commissioning
1System engineering acceptance·
General provisions
Subjective evaluation of system quality
3Testing of system quality
Engineering construction standard full text information system
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Engineering Construction Standard Full Text Information System
Engineering Construction Quality of the System
5 Acceptance Documents
Appendix A
Appendix B
Appendix C
Appendix D
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Common Graphic Symbols in the Basic Mode of the System Common Test Tables
Engineering Acceptance Certificate of the System
Terms Used in This Standard
Additional Notes
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Engineering Standard Full Text Information System
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Engineering Construction Standard Full Text Information System
1 In order to make the engineering design and construction of cable television systems (hereinafter referred to as systems) 1.0.1
technically advanced, economically reasonable, safe and applicable, and ensure quality, this specification is formulated. 1.0.2
2This specification applies to the design, construction and acceptance of new construction, expansion and reconstruction projects of cable television systems with the following signal transmission methods: 1.0.2.1RF coaxial cable.
2RF coaxial cable combined with optical cable.
1.0.2.3RF coaxial cable combined with microwave. 3 The engineering design of the system shall comply with the requirements of the local urban construction plan and the development plan of the radio and television industry and cable television network. 1.0.4 In addition to being implemented in accordance with this specification, the engineering design and construction of the system shall also comply with the provisions of the relevant current national standards and specifications.
Engineering Construction Standard Full Text Information System
Engineering Construction Standard Full Text Information System
2 Engineering Design of the System
General Provisions
2.1.1 The selection and number of channels to be used shall be determined based on the current status, development and economic conditions of signal sources such as television broadcasting, FM broadcasting, satellite reception, microwave transmission, and self-produced programs, and shall meet the following requirements:
2.1.1.1 It is advisable to reserve 1 to 2 channels.
It is advisable to avoid combined interference of various frequencies. For unavoidable interference, measures such as changing channels should be taken.
2.1.2 Determination of the transmission mode. When the attenuation of the transmission trunk line (based on the attenuation value at the highest operating frequency) is less than 100dB, the very high frequency (VHF) and ultra-high frequency (UHF) direct transmission methods can be used; when the attenuation of the transmission trunk line is greater than 100dB, the very high frequency (VHF) transmission method or adjacent frequency transmission method should be used. 2.1.3 The system mode should be determined based on factors such as signal source quality, environmental conditions, and system scale and function. The front end should be set at the center of the coverage area. When the received signal field strength is less than 57dBuV, measures such as adding a remote front end can be taken. 2.1.4 According to the system mode, the main technical indicators of the front end, trunk line and distribution network should be allocated and calculated.
2.1.5 The selection of equipment, components and materials should comply with the following provisions: 2.1.5.1 The performance of the product shall comply with the provisions of the current relevant national standards and shall be tested and certified by the national quality inspection department.
2.1.5.2 The performance and appearance of the main components and materials selected in the same system project should be consistent.
2.1.5.3 The input and output nominal impedance of the selected equipment and components, and the nominal characteristic impedance of the cable should all be 752.
2.1.6 The ambient temperature of the system facilities should meet the following requirements: Engineering 2 Standard Information System
Engineering Construction Standard Information System
Outdoor facilities in cold areas: -40 to +35°C, outdoor facilities in other areas: -10 to +55°C; indoor facilities: -5 to +40°C. 2.2
Basic modes and main technical indicators of the system The distribution system can adopt four basic modes: trunkless system, independent front-end system, central front-end system, and remote front-end system, and should meet the following requirements: 2.2.1.1 The trunkless system mode is very small in scale and does not require transmission trunks. It is directly led from the front end to the user distribution network (Figure 2.2.1-1). User distribution part
Figure 2.2.1-1 Trunkless system mode
The independent front-end system mode is a typical cable transmission and distribution system, which consists of the front end, trunk, branch and user distribution network (Figure 2.2.1-2). 2.2.1.3 The system model with central front end is large in scale. In addition to the local front end, a central front end should be set up at the center of each dispersed coverage area; the local front end can be connected to each central front end by a trunk line or super trunk line, and each central front end is connected to the branch line and user distribution network through the trunk line (Figure 2.2.1-3). 2.2.1.4 The system model with remote front end, the local front end is too far away from the signal source, and the remote front end should be set up near the signal source to send the received signal to the local engineering construction standard full text information system
engineering construction standard full text information system
front end via the super trunk line (Figure 2.2.1-4).
ATATAN
Branch line and user distribution part
Branch line and user distribution part
Independent front end system model
Figure 2.2.1-2
Central front end
Central front end
Central arrow end
Super trunk line
Super trunk line
ATATAH
Figure 2.2.1-3
System mode with central front end
Engineering construction standard full text information system
Engineering construction standard full text information system
Branch line and user allocation part
Super trunk line
Remote front end
Branch line and user allocation part
1System mode with remote front end
Figure 2.2.1-4
Note: The commonly used graphic symbols in the basic mode of the system shall comply with the provisions of Appendix A of this specification. 2 The minimum design values ​​of the system carrier-to-noise ratio, cross-modulation ratio and carrier intermodulation ratio shall comply with the provisions of 2.2.2
Combined with Table 2.2.2.
Minimum design values ​​(dB) of system carrier-to-noise ratio, cross modulation ratio and carrier intermodulation ratio
Carrier-to-noise ratio (C/N)
Cross modulation ratio (CM)
Carrier intermodulation ratio (IM)
Design value
The allocation coefficients of the main technical indicators of the front-end, trunk and distribution parts of various system modes shall comply with the following provisions:
2.2.3.1 The indicator allocation coefficients of the non-trunk system shall comply with the provisions of Table 2.2.3-1.
Engineering Construction Standard Full-text Information System
Engineering Construction Standard Full-text Information System
Carrier-to-noise ratio
Cross-modulation ratio
Carrier intermodulation ratio
Indicator allocation coefficient of non-trunk system
Table 2.2.3-1
Distribution network
The indicator allocation coefficient of the independent front-end system should be selected according to the attenuation value A (dB) of the trunk line and the provisions of Table 2.2.3-2. Index allocation coefficient of independent front-end system
Carrier-to-noise ratio
Cross-modulation ratio
Carrier intermodulation ratio
A<100dB
A100dB
A<100dB
Table 2.2.3-2
Distribution network
A<100dB
A≥100dB
A≥100dB
The index allocation coefficient of the system with central front-end and remote front-end shall comply with the provisions of 2.2.3.3
Table 2.2.3-3.
Central front-end and remote front-end system index allocation coefficient items
Carrier-to-noise ratio
Cross-modulation ratio
Carrier intermodulation ratio
Local front-end
Remote front-end
Central front-end
Local trunk
(super trunk)
Table 2.2.3-3
Central trunk
Distribution network
The decibel (dB) of carrier-to-noise ratio, cross-modulation ratio and carrier intermodulation ratio can be calculated according to the following formula:
[C/N]x=44—10lga
[CM]x—47—201gb
[IM,Jx=58-10lgc
Engineering Construction Standard Full Text Information System
(2.2. 4-1)
(2.2.4—2)
(2.2.4—3)
Engineering Construction Standard Full-text Information System
IM,Jx=58—10gc
[C/N]x—the decibel number assigned to a certain part of the carrier-to-noise ratio In the formula
—the coefficient assigned to the carrier-to-noise ratio of that part; (2.2.4—4)
[CM]x—the cross-modulation ratio assigned to a certain part decibel number; 6
- coefficient assigned to the cross-modulation ratio index of this part; {IM,]x—decibel number assigned to a part of the second-order carrier intermodulation ratio; coefficient assigned to this part of the carrier intermodulation ratio; (IM,Jx——decibel number assigned to this part of the third-order carrier intermodulation ratio. 2.2.5
The design value of the system output level should meet the following requirements: 2.2.5.1 Non-adjacent frequency system can take 70±5dBuV. 2.2.5. 2
Systems using adjacent frequency transmission can take 64±4dbuV. Note: The level can be increased on higher floors in strong field areas to avoid co-channel interference. 2.2.6
The design value of the level difference between channels at the system output port should not be greater than the provisions of Table 2.2.6.
Level difference between channels at the system output port (dB)
Any channel
Adjacent channel
UHF band
VHF band
Any 60MHz in the VHF band
Any 100MHz in the UHF band
Receiving antenna
Level difference at the system output port
2.3.1 The receiving antenna should be installed at a higher place, avoiding obstacles in the direction of receiving radio wave transmission and surrounding metal components, and should be away from interference sources such as roads, electrified railways, high-voltage power lines and industrial interference. Engineering Construction Standard Full-text Information SystemJx——Decibel number of the third-order carrier intermodulation ratio assigned to this part. 2.2.5
The design value of the level at the system output port should meet the following requirements: 2.2.5.1 Non-adjacent frequency systems can take 70±5dBuV. 2.2.5.2
Systems using adjacent frequency transmission can take 64±4dBuV. Note: The level can be increased on higher floors in strong field areas to avoid co-channel interference. 2.2.6
The design value of the level difference between channels at the system output port should not be greater than the provisions in Table 2.2.6.
Level difference between channels at the system output port (dB)
Any channel
Adjacent channels
UHF band
VHF band
Any 60MHz in the VHF band
Any 100MHz in the UHF band
Receiving antenna
Level difference at the system output port
2.3.1 The receiving antenna should be installed at a higher place, avoiding obstacles in the direction of the received radio wave transmission and surrounding metal components, and should be away from interference sources such as roads, electrified railways, high-voltage power lines and industrial interference. Engineering Construction Standard Full Text Information SystemJx——Decibel number of the third-order carrier intermodulation ratio assigned to this part. 2.2.5
The design value of the level at the system output port should meet the following requirements: 2.2.5.1 Non-adjacent frequency systems can take 70±5dBuV. 2.2.5.2
Systems using adjacent frequency transmission can take 64±4dBuV. Note: The level can be increased on higher floors in strong field areas to avoid co-channel interference. 2.2.6
The design value of the level difference between channels at the system output port should not be greater than the provisions in Table 2.2.6.
Level difference between channels at the system output port (dB)
Any channel
Adjacent channels
UHF band
VHF band
Any 60MHz in the VHF band
Any 100MHz in the UHF band
Receiving antenna
Level difference at the system output port
2.3.1 The receiving antenna should be installed at a higher place, avoiding obstacles in the direction of the received radio wave transmission and surrounding metal components, and should be away from interference sources such as roads, electrified railways, high-voltage power lines and industrial interference. Engineering Construction Standard Full Text Information System
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