1) Network wiring system
A) Introduction to the system:
PDS (Premises Distribution System) is designed for the distribution system of computer and communication, which shows that it can meet various requirements of computer and communication. It includes analog and digital voice system, high-speed and low-speed data system, image data needed to be transmitted by fax machine, graphic terminal and plotter, video signal of video conference and safety monitoring system, safety alarm of integrated wiring for buildings and sensor signal of air conditioning control system, etc.
B) Performance requirements:
The network involves many contents and protocols, Each protocol has its own characteristics on the basis of following international standards, There are some differences in wiring requirements. At the same time, with the development of technology, users' demand for bandwidth and bandwidth increases. The requirement for wiring is not to change greatly, but to adapt to new technologies and the increase of user stations or transmission rate, and to have better intelligence and flexibility. As the foundation of the whole network system and even the whole integrated system, the wiring system must have such characteristics;
Practicability: The wiring system should be able to fully adapt to the modern and future technical development, realize voice, high-speed data communication and high-visualization picture transmission, and support various network equipment, communication protocols and wide applications including management information systems, business processing activities and multimedia systems. The wiring system can also support other non-data communication applications, such as telephone system.
Advanced: As the infrastructure of the whole building, the wiring system should adopt advanced science and technology, focus on the future, and ensure that the system has a certain advance, so that the wiring system can support the future network technology and application.
Flexibility: The wiring system is independent of the equipment it serves and can meet the requirements of various applications. Each information point can be connected with different equipment, such as data terminals, analog or digital telephones, program-controlled telephones or extensions, personal computers, workstations, printers, multimedia computers, and mainframes. The wiring system should be able to connect into different logical structures including star, ring and bus.
2) Security closed-circuit monitoring system
A) Introduction to the system:
Structurally speaking, the video monitoring system consists of front-end equipment, transmission equipment, control equipment, display and recording equipment. The front-end equipment consists of high-resolution color cameras, full-automatic lenses, outdoor and indoor professional protective equipment installed at designated positions on site, and is responsible for image and data acquisition and signal processing; Transmission equipment can choose various cables and interface equipment according to the requirements of transmission distance and image quality, and is responsible for transmitting video and data signals to the required places; The control equipment is responsible for the control of front-end equipment, image switching equipment, omni-directional pan/tilt, lens, etc., and can also complete functions such as image retrieval and processing as required; Display and recording equipment can select different image display equipment according to different image display requirements, such as hard disk, video recorder (long delay), monitor, display, projector, large screen, etc.
B) Performance requirements:
The design and construction of the security system should fully consider the recent needs of the center and the needs of updating, adjusting, developing and upgrading exhibits or changing functions in the future, so that it can adapt to the present and face the future, and ensure the application needs for 10-15 years. Therefore, the security monitoring system should have the following performance:
Practicability: Adopt economical and practical technology and equipment, comprehensively consider the construction, upgrade and maintenance costs of the system, do not blindly invest, meet the system requirements in scheme design, fully consider the use requirements of various monitoring parts, make the functions of the system perfect as much as possible and make full use of it, ensure the high performance price ratio, and ensure the safe, efficient and long-term operation of the system; Ensure high-quality and timely after-sales service.
Reliability: System design, equipment selection, commissioning, installation and other links will strictly implement the quality regulations, fully comply with the bidding documents, relevant national and industrial standards and relevant safety technical prevention requirements of public security departments. The system has consistency, upgrade ability and technical support, which can ensure all-weather long-term stable operation.
Scalability: No matter any project, we will be in the long term. Viewpoint, so that the system can be expanded, capacity can be expanded. On the premise of emphasizing the careful consideration of technical defense measures at different levels, we should actively and seriously combine various entry and physical defense measures and rules and regulations formulated by the security department, suggest and remind to strengthen physical defense measures in important places, so as to organically combine technical defense, civil air defense and physical defense to ensure the establishment of a complete security system.
3) Cable TV system
A) Introduction to the system:
CATV system can generally be divided into three parts: antenna, front-end, trunk and branch distribution network. The antenna part adopts cable TV special receiving antenna, FM FM broadcasting antenna, self-broadcasting program equipment and various satellite antennas. The front-end part includes a V converter, a channel amplifier, a pilot signal generator, a modem, a mixer and special receiving equipment for satellite TV. The trunk and branch distribution network part comprises a trunk transmission cable, a trunk amplifier, a line equalizer, a distribution amplifier, a line extension amplifier, a branch cable, a distributor, a branch and a user output.
B) Performance requirements:
The main task of the system is to transmit the TV signal provided by the front end to the input port of the distribution network of the system without distortion through the transmission medium, and its signal level should meet the requirements of the distribution network of the system, so that the TV set of the user terminal is in the best working state. At present, a large number of CATV systems use coaxial cable as the transmission medium of the main line of the system. Because of the attenuation of high-frequency TV signals transmitted in coaxial cable, the attenuation depends not only on the structure and material of coaxial cable, but also on the frequency of the signal itself. The higher the frequency, the greater the attenuation of the signal under the same conditions. In this way, when the signal is transmitted for a certain distance, the signal level will drop, and the farther the distance, the greater the drop value, and the level of signals with different frequencies will have a difference, and the farther the transmission distance, the greater the difference. This brings difficulties to the normal work of the system distribution network. In addition, the attenuation of signal is also related to temperature, and the attenuation increases by about 0.2% dB/C when the temperature rises. In order to overcome the attenuation caused by signal transmission in cable and the attenuation difference of signals with different frequencies, besides coaxial cable with small attenuation, trunk amplifier and equalizer with automatic gain control and automatic slope control functions are also adopted.