This specification is applicable to the construction, expansion and reconstruction of the common antenna television system of general industrial enterprises. For the expansion and reconstruction projects, it is necessary to proceed from the actual situation and pay attention to making full use of the original facilities. GBJ 120-1988 Design Specification for Common Antenna Television System of Industrial Enterprises GBJ120-1988 Standard download decompression password: www.bzxz.net

Engineering Construction Standard Full Text Information System
National Standard of the People's Republic of China
Industrial Enterprises Shared Antenna Television
System Design Specification
GBJ120—88
1989Beijing
Engineering Construction Standard Full Text Information System
W Engineering Construction Standard Full Text Information System
National Standard of the People's Republic of China
Industrial Enterprises Shared Antenna Television
System Design Specification
GBJ120—88
Editor Department: Post Office of the People's Republic of China Ministry of Posts and Telecommunications Approval department: State Planning Commission of the People's Republic of China Effective date: December 1, 1988
Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
Notice on the release of "Design Specifications for Industrial Enterprises' Shared Antennas and Television Systems"
Ji Biao [1988] No. 457
According to the requirements of the State Planning Commission's Ji Zong [1986] No. 250 document, the "Design Specifications for Industrial Enterprises' Shared Antennas and Television Systems" jointly compiled by the Ministry of Posts and Telecommunications and relevant departments has been reviewed by relevant departments. The "Design Specifications for Industrial Enterprises' Shared Antennas and Television Systems" GBJ120-88 is now approved as a national standard and will be implemented from December 1, 1988. This specification is managed by the Ministry of Posts and Telecommunications. Its specific interpretation and other work are the responsibility of the Beijing Design Institute of the Ministry of Posts and Telecommunications. The publication and distribution is the responsibility of China Planning Press. State Planning Commission
March 24, 1988
Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
Preparation Instructions
The "Design Specifications for Shared Antenna Television Systems for Industrial Enterprises" was prepared by our department in conjunction with the Ministry of Metallurgy in accordance with the requirements of the State Planning Commission's Document No. [1986] 250.
During the preparation of this specification, a relatively extensive investigation, analysis and experimental verification were carried out, the experience of the construction of shared antenna television projects for industrial enterprises was summarized, and the opinions of relevant units across the country were widely solicited. Finally, the draft was reviewed and finalized in conjunction with relevant departments. This specification has nine chapters and two appendices, and the main contents include: general principles, system design, antenna, front end, line, user allocation, video playback room and TV station, power supply, lightning protection and safety protection, etc.
During the implementation of this specification, all units are requested to accumulate information and summarize experience. If any modification or supplement is found, please send your opinions and relevant information to the Beijing Design Institute of the Ministry of Posts and Telecommunications (No. 11, Yuetan South Street, Beijing) for reference in future revisions. Ministry of Posts and Telecommunications
March 1988
Engineering Construction Standard Full Text Information System
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Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Chapter 9
System Design
User Allocation·
Video Studio and TV Station|| tt||Lightning protection and safety protection
Term explanation
Explanation of terms used in this specification
Additional explanation
Engineering construction standard full text information system
: (13)
: (21)
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Chapter 1 General Provisions
Article 1.0.1 This specification is formulated to ensure that the design of industrial enterprise shared antenna television systems complies with relevant national guidelines and policies and is technologically advanced, economically reasonable, safe and applicable.
Article 1.0.2 This specification applies to the construction, expansion and reconstruction of general industrial enterprise shared antenna television systems. For expansion and reconstruction projects, it should proceed from reality and pay attention to making full use of existing facilities.
Article 1.0.3 The technical indicators of the shared antenna television system shall comply with the parameter requirements of the current national standard "Cable Distribution System for Sound and Television Signals of 30MHz to 1GHz"; the quality of the signal entering the system and the transmission quality of the system shall comply with the following provisions:
The quality of the television signal entering the front end of the system should not be lower than level 2.75 of the five-level quality scale;
2. The damage of the system to the transmitted television signal (excluding the antenna and its feeder) should not cause the non-degraded signal to degrade (for any single electrical performance) to less than level 4 of the five-level damage scale.
Article 1.0.4 In addition to implementing this specification, the design of the shared antenna television system for industrial enterprises shall also comply with the current national "Industrial Enterprise Communication Design Specification", "Industrial Enterprise Communication Grounding Design Specification", "Building Lightning Protection Design Specification", "Explosion and Fire Hazardous Places Power Installation Design Specification" and other relevant specifications. Engineering Construction Standard Full Text Information System
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Chapter 2 System Design
Article 2.0.1 A common antenna television system can be composed of antenna, front end, line distribution, user distribution and other parts.
Article 2.0.2 A common antenna television system can be set up in the following places of industrial enterprises:
1. Office buildings, teaching buildings, halls and other places where radio frequency modulated images, sounds and other information that can be transmitted need to be transmitted through a common antenna television system; 2. Cultural and educational places such as clubs, cultural and educational halls, and training centers; 3. Factory and mine guesthouses or hotels;
4. Buildings in residential areas of factories and mines. www.bzxz.net
Article 2.0.3 Industrial enterprises in areas where wireless broadcasting and television signals are blocked, the field strength is weak, the distribution is uneven, or there is local interference can establish a common antenna television system by reasonably selecting the antenna position.
Article 2.0.4 The planning and design of the common antenna television system shall meet the following requirements:
1. Meet the needs of enterprise management and cultural education of employees;
2. Be compatible with the development plan of the enterprise;
3. Be compatible with the development plan of local radio and television. 4. The planning and design shall include the following contents: 1. User number forecast and regional division:
2. Plan for the number of broadcasting and television programs and the transmission of other information;
3. Requirements and development plan for the establishment of video studios and television stations for self-produced programs;
4. System composition, antenna installation and signal remote transmission plan;
5. Equipment selection;
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6. Buildings and building areas required for the establishment of the common antenna television system;
7. Power supply plan;
8. Construction sequence:
9. Investment and effect forecast.
Article 2.0.5 Large and medium-sized industrial enterprises should establish a network of shared antenna television systems based on the enterprise structure, regional distribution and terrain conditions, and for the convenience of enterprise management. When one front end governs all users and cannot ensure the signal indicators of the farthest system output port, a central front end should be added to establish a shared antenna television signal transmission system in a partitioned manner.
Article 2.0.6 Industrial enterprises with large land areas can set up multiple independent shared antenna television systems if there are obstacles such as rivers, mountains, ditches, etc. in their factory areas that hinder the laying of lines or the factory buildings are relatively scattered. Article 2.0.7 When designing a shared antenna television system, television channels specified in the national cable television frequency configuration should be selected to transmit television signals. Article 2.0.8 The nominal impedance of signal transmission in the shared antenna television system should be 750.
Article 2.0.9 The signal level of any television channel output from the output port of the shared antenna television system should comply with the provisions of Table 2.0.9, and it is advisable to use 70±5dBμV as the calculation control range.
User Level Range Table
Maximum Level (dBμv)
Minimum Level (dBuv))
Note: Each level value in the table refers to the effective value of the image carrier voltage at the peak of the modulation envelope, which is the value measured from the 75Q matching load.
The level difference between different frequency signals output from the output port of the common antenna television system shall comply with the provisions of Table 2.0.10. System output signal level difference tolerance value
30MHz—1GHZ
30MHz—300MHz
Any 60MHz frequency domain in VHF frequency band
Any 100MHz frequency domain in UHF frequency band
Between adjacent TV channels
Note: The meaning and measurement method of the level are the same as those in the notes of Table 2.0.9. Table 2.0.10
Maximum level difference
Tolerance value (dB)
Section 2.0.Article 11 When there is a matching load at the system output port, the isolation should not be less than 22dB.
The noise measurement bandwidth is 5.75MHz, and the system carrier-to-noise ratio Article 2.0.12
(C/N) should not be less than 43dB.
Article 2.0.13 The carrier-to-noise ratio in the common antenna television system can be allocated according to the following provisions:
, as shown in Figure 2.0.13-1, when there is only one front end in the signal transmission allocation route, the carrier-to-noise ratio index should be allocated according to Table 2.0.13-1. Input
Line allocation
(C/NOL
(C/NB
User allocation
Figure 2.0.13—11 Carrier ratio allocation of front-end systems Output
II. As shown in Figure 2.0.13-2, there are 2 front-ends in the signal transmission distribution route. Engineering 4 Construction Standard Full-text Information System
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1 Carrier-to-noise ratio allocation of front-end system
Road section situation
There are active devices in the front-end, line allocation, and user allocation sections
There are active devices in the front-end and line allocation sections, and no active devices in the user allocation section
There are active devices in the front-end and user allocation sections, and the line allocation There is no active equipment in the section
There is active equipment in the front end, and there is no active equipment in the line distribution and user distribution sections
There is active equipment in the line distribution and user distribution sections, and there is no active equipment in the front end
There is active equipment in the line distribution section, and there is no active equipment in the front end and user distribution sections
(C/N)H2
Table 2.0.13-1
(C/N)Lg
(C/N)s
When the carrier-to-noise ratio of the first part is preferably 47dB, the carrier-to-noise ratio of the second part is preferably 45dB. The carrier-to-noise ratio of the two parts should be allocated according to Table 2.0.13-2a; Table 2.0.13-2b. Input
Local end
Daily line allocation
CN1-1aB
Center front end
Line allocation
(C/N)2-45dls
User allocation
Figure 2.0.13—22 front end system carrier-to-noise ratio allocation Engineering Construction Standard Full Text Information System
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2 front end systems front half carrier-to-noise ratio allocation section situation
There are active devices in the front end and line allocation section. There are no active devices in the line allocation section. There are active devices in the front end and line allocation section. (C/N)
2 front end systems, the second half carrier-to-noise ratio allocation section situation
There are active devices in the front end, line allocation, and user allocation sections
Front end and line allocation section There are active devices in the front end, and no active devices in the user allocation section
There are active devices in the front end and user allocation section, and no active devices in the line allocation section
There are active devices in the front end, and no active devices in the line allocation and user allocation sections
There are active devices in the line allocation and user allocation sections: no active devices in the front end
There are active devices in the line allocation section, and no active devices in the front end and user allocation section
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Table 2.0.13-2a
Table 2.0.13-2d
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Chapter 3 Sky
Article 3.0.1 To receive wireless television broadcasts, a dedicated receiving antenna should be set for each channel. Within the scope of wireless broadcasting and television services, the performance of the receiving antenna can be determined according to Table 3.0.1.
Main performance requirements of receiving antenna
I(1~5 channels)
I(6~12 channels)
N, V(13~48 channels)
>6 (9)
>8 (11)
Front-to-back ratio
Note: The values ​​in brackets should be used when approaching the edge of the service area. Half-power angle
Yagi antenna
Number of units
Article 3.0.2 The antenna broadcasting and television receiving field strength can be predicted by the following methods: 1. In plain areas, the radio wave propagation distance is less than 30km, and it is advisable to estimate it according to the calculation formula (3.0.2-1) or (3.0.2-2) of the spatial wave field strength. E
【444X103VPt·Gt
2ht·hr
(land·d×103
(3. 0.2—1)
When the condition of d≥18Xht·hr／（a×10°）is satisfied, the above formula can be approximated as: E=2. 79X10° . ht · hr VPt .Gtland·d2
Engineering Construction Standard Full-text Information System
(3.0.2—2)
W.bzsoso：cOn1 Determine.
Main performance requirements of receiving antenna
I(1~5 channels)
I(6~12 channels)
N, V(13~48 channels)
>6 (9)
>8 (11)
Front-to-back ratio
Note: The values ​​in brackets should be used near the edge of the service area. Half-power angle
Yagi antenna
Number of units
Article 3.0.2 The antenna broadcasting and television receiving field strength can be predicted by the following methods: 1. In plain areas, the radio wave propagation distance is less than 30km, and it is advisable to estimate it according to the calculation formula (3.0.2-1) or (3.0.2-2) of the spatial wave field strength. E
【444X103VPt·Gt
2ht·hr
(land·d×103
(3. 0.2—1)
When the condition of d≥18Xht·hr／（a×10°）is satisfied, the above formula can be approximated as: E=2. 79X10° . ht · hr VPt .Gtland·d2
Engineering Construction Standard Full-text Information System
(3.0.2—2)
W.bzsoso：cOn1 Determine.
Main performance requirements of receiving antenna
I(1~5 channels)
I(6~12 channels)
N, V(13~48 channels)
>6 (9)
>8 (11)
Front-to-back ratio
Note: The values ​​in brackets should be used near the edge of the service area. Half-power angle
Yagi antenna
Number of units
Article 3.0.2 The antenna broadcasting and television receiving field strength can be predicted by the following methods: 1. In plain areas, the radio wave propagation distance is less than 30km, and it is advisable to estimate it according to the calculation formula (3.0.2-1) or (3.0.2-2) of the spatial wave field strength. E
【444X103VPt·Gt
2ht·hr
(land·d×103
(3. 0.2—1)
When the condition of d≥18Xht·hr／（a×10°）is satisfied, the above formula can be approximated as: E=2. 79X10° . ht · hr VPt .Gtland·d2
Engineering Construction Standard Full-text Information System
(3.0.2—2)
W.bzsoso：cOn
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