【 Weak current College 】 satellite TV receiving system and cable TV systems engineering construction site coordination and control

Construction content overview
(1) satellite TV receiving system is composed of the uplink station (uplink), satellite Astral (satellite transponder) and ground reception (downlink station).
1) uplink stations can be fixed or movable Earth station for large ground stations, the use of directional antennas to send the signal and the sound signal, after treatment of enlarged, sent to the satellite transponders. Among other uplink station, main uplink station has two tasks: one is to provide programs that Astral is receiving the Astral downlink signal to monitor programme quality and the satellite attitude, run by uplink station random to issue amended directive, the Astral change satellite position and attitude, adjust the antenna and switching equipment, ensure the system is operating normally.
2) satellite transponder to uplink signal received is converted into downlink frequency-modulated signal, magnified by the directional antenna to the ground to launch.
3) ground receiving stations received satellite transponder downlink frequency-modulated signal, after demodulation of frequency, and then sent to cable TV (CATV) systems, the composition is the satellite TV receiving system and cable TV reception system front-end basic composition.
(2) cable television (CATV) systems is determined by the receiving section, front-end part, main transmission and distribution network.
Part: 1) to receive mainly through a high gain of parabolic satellite receiving antenna for satellite microwave signal reception.
The front-end part 2): the reduced frequency converter (LNB LNB), and satellite TV receiver.
Reduced frequency converter is to receive the satellite antenna to RF signal (C-band, its frequency 3.7 ~ 4.2GHz), down to if signal, 970 ~ 1470MHz, this equipment mainly from low noise amplifier and down converters.
Satellite TV receivers feature is the satellite TV signals, restored into a standard TV interface level of images and sounds, supply general television program.
3) trunk transport: CATV system route transfer some of the features are the output of the front-end part of the television signal distortion at high frequency stability is not passed to the system-assigned network input ports, output level signal should meet the system requirements to distribution networks. Often using the route with coaxial cable transmission and optical fiber cable transmission.
4) distribution network: its function is to provide the front end of the high-frequency TV signal, after the route is transferred to the Branch Manager, and then transfer to the Terminal Distributor, supplying user TV program.
Construction site coordination points
1. construction and civil engineering structures with points
(1) satellite TV receiving antenna lightning protection:
1) civil construction combined with satellite TV receiving antenna for reinforced concrete foundation, the bottom layer of reinforced and the Earth. When the measured reinforced earth resistance less than 4 Ω, for lightning protection and earthing. On the basis of anchor bolts embedded in, and connected with mesh reinforcement, therefore, lightning can be directly connected with bolts, do lightning protection grounded. When the base reinforced earth resistance is greater than 4 Ω, separate secondary ground electrode.
2) when the satellite TV receiving antenna is installed in the building roof, simply use the antenna's lightning rod and building mine earthing network connected to the pass.
3) pursuant to the product description in the callout antenna embedded parts and pre-embedded dimensions and various technical requirements, with a wind speed of the bearing points under the antenna maximum pulling force, pressure and lateral force. You only need to provide a basis for structural engineers to design the roof specifications, antenna base. Design officer pursuant to the supporting point of antenna geometry size, design a set of reinforced concrete beams or steel girder beam system. Beam system supporting the building of a post or reinforced concrete shear walls or brick wall, antenna mounted in a beam, girder, through the Foundation block doesn't will force to post and the wall. Base block doesn't want to set the anchor bar so that it can withstand the antenna passes of tension or stress. Note: the antenna Foundation position should determine true North, and construction.
(2) cable television system antenna lightning protection:
1) antenna vertical rods can directly fixed on buildings, such as the building up of the elevator or tank of load-bearing walls.
2) antenna vertical rods fixed in the embedded steel pipe-or channel-base, the base must be located in the load-bearing walls or load-bearing beam, and the building of lightning protection earthing network connectivity.
3) free-standing Tower antenna on the Eiffel Tower, with a view to establishing working table must be in the installation system parts and maintenance, lighting and other technical support. There should be a strong wind-resistant iron Tower, lightning protection and grounding device.
4) should use windproof laces the antennas vertical rods fixed to ensure that the location of the receiving antenna.
(3) cooperate with the civil construction, Interior buried pipes, the user box and connection box, reserved hole, embedded iron.
2. and the earth building decoration engineering construction coordination points
(1) burying ceiling construction, cable tray or trunkings construction.
(2) civil construction for indoor Terminal user box stuffing and panel installation, both box with installation.
(3) in the room out with pipeline construction, and with the professional coordination of construction of the pipeline.
3. satellite TV receiving system and cable TV system outdoor overhead (bar) or the grooves in the laying of cables, it is timely to provide open trench route civil engineering, construction by civil assistance.
In the outdoor underground open trench before to be cable of routing the following other professional pipeline, in case of other pipeline and Street road, should wear protective tube.
4. set up the wall cable first wall with good wall supported and support rail, and cabling.
Construction site control focus
(1) audit satellite TV receiving system and cable TV system by system, user-level distribution maps, routes, floor plans, antenna location and installation diagram, whether by have the legal qualification of design unit design, confirm construction drawing available before construction.
(2) carefully review construction drawings, you will find a summary of issues central to the design, organization design gives the low-down, put questions to form a solution file, to be checked to confirm, and prompt to doLogic design change process.
(3) the audit of satellite television receiving system and cable TV system construction organization plan.
1) satellite TV receiving system and cable TV systems engineering construction used equipment materials ordering schemes, labour scheduling and construction schedule, and so should the General and civil engineering construction schedule, make sure that the total duration of a schedule.
2) satellite TV receiving system and cable TV systems engineering construction technology gives the low-down. Clear the professional installation of the main elements of the task, and the operator, demonstrate technological operation requirements and to achieve the quality standards, and security considerations and professional construction coordination issues.
3) requirements for equipment purchase: purchase of equipment according to the current mission requirements, and consider the future development. Purchase of equipment is run by the national certification and approval of fixed-point manufacturers the products. If you choose to select foreign products, brands, and should not be buying inferior quality products. Note: the purchase of the antenna to the formalities to the relevant departments of the bid to purchase.
4) satellite receiving antenna Foundation construction, in winter the frozen layer, based in the North should be buried deep beneath the frozen soil layer.
5) lightning lightning protection line should be independent of the connection, do not allow the lightning protection, with interior reception equipment grounding line sharing, otherwise it may have been caused by lightning strikes back, burned, or even damage the device and the security of the person.
6) against lightning earthing devices impulse resistance value should be less than 4 Ω.
7) antenna rod (Tower) is higher than the surrounding buildings, structures, and the height above the 50m, high barrier lamp should be installed, and rod (Tower) was painted red and white colors. City and airport, the airspace within a high tower also apply to the consent of the relevant departments.
8) active parts should be powered up check on major parts, such as amplifier, modulator, filter mixer, etc, should make the necessary technical tests to avoid loading one system fails, to debugging work bring difficulties, the delay duration.
9) where a waterproof shell is not set main amplifier, if installed, should be mounted waterproof device protection.
10) using the power plug in person for the trunk amplifier power supply, power supply plug should be set up in person with bridge amplifier.
11) supply power supplies, power lines and cables and the pole if the erection of the wire to use insulated conductors can be mounted in a cable from the cable 0.6m above above.
12) optical fiber cable laying before, you should check if breakpoints, optical fiber attenuation value meets the design requirements.
13) matching fiber length, based on construction drawings to the actual length of the cable to the matching. When you want to make the disks in the connector from the rubble, major traffic arteries and other obstructions.
14) laying cable, optical cable traction end should be good technology should be used with automatic control of the traction performance traction machine, traction force should be imposed to strengthen core, maximum should not exceed 150kg, haul-off speed appropriate 10m/min, a length of line drawing should not be more than 1km. Cloth on fiber-optic cable, the minimum bending radius not less than 20 times the cable diameter.
15) General overhead cable without leaving residual pockets that should not be strained. Each piece of fiber optic cable installation is complete, end the application, the plastic tape wrapped joints of top stay length is not greater than 8m and Yu cable disc circle after hanging Rod heights. Underground cable strung poles must wear protective tube tubes, cited on the rod after the start of overhead can stay fit while pocket.
Optical cable 16) pipeline is set, no connector cable laying on the straight road shall be determined by the artificial one by one into the hole, prior to the optical connector, the connector part through the pipe.
17) optical fiber cable of continued to be performed by trained personnel, should be used when connecting power or other instrument for monitoring the continued loss of minimum. Continuation after installing fiber optic cable sheath.
18) satellite TV receiving system and cable TV system of inspection, testing and measurement:
① system check information check; the use of equipment and tools; antennas, equipment and lines of security checks.
② system common debugging instruments prepared, such as the field strength meter, Sweeper, spectrum analyzers, signal generators, color TV-monitor, grounding resistance Tester and other instruments.
③ system debugger: satellite TV receiving antenna for debugging; sharing of receiving antenna for debugging; front-end device debugging, the debug main transmission network; extension and the user distribution network debugging. After the system's unified debugging, and test results are recorded in the requirements of the table, the logging data shall be consistent with existing national standards and regulatory requirements and meet the design requirements and regulations.