03-07-2012, 04:42 PM
TV CABLE NETWORKING
[attachment=26577]
Coaxial cables have been used to construct the cable TV distribution network. At the beginning, a cable TV distribution network was very simple and consisted of coaxial cables connecting an antenna on a hillside to many homes that did not get good reception using their rooftop antennas. To compensate for signal losses caused by branch splitting and cable attenuation, TV signals picked up by the hillside antenna are usually enhanced by a wide-band amplifier, whose bandwidth covers TV channels of interests, raising the signal level by 10 to 25 dB .
In-House Wiring Configuration
In a new construction, coaxial cables are connected from a central location near the TV signal source, be it a cable TV or a satellite dish, to every room where an in-house TV wiring connection should be available. This configuration forms a star topology.
A multiport splitter is located at the center of the star. Depending upon the number of rooms to be served, some times an amplifier is inserted between the video source and the multiport splitter to raise the signal level, compensating signal losses caused by branch splitting.
Hybrid Fiber Coaxial and Tree Branch Distribution Plant
The general arrangement of the cable TV hybrid fiber coaxial and tree branch distribution network connecting all subscribers. TV signals are originated from the head end. Two-way services such as cable modem for Internet access and POTS are also terminated and managed at the head end .
A dual optical ring is used to connect all head ends and hubs over the SONET and ATM infrastructure for delivering and exchanging digital programs. AM fiber links are extended to a number of fiber nodes. From each fiber node, a few coaxial trunk cables, each of which serves a few hundred subscribers, are further extended to neighborhoods. Subscribers are connected to trunk cables through drop coaxial cables.
DISH ANTEENA
A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or parabolic dish.
The main advantage of a parabolic antenna is that it is highly directive; it functions similarly to a searchlight or flashlight reflector to direct the radio waves in a narrow beam, or receive radio waves from one particular direction only.
RECEIVER
The equipment used to receive the transmitted modulated radio-frequency signals and produce synchronized visual images and sound. The radio-frequency portion operates on the superheterodyne principle.
Television receivers designed to produce images in full color are necessarily more complex than those designed to produce monochrome images only. In monochrome systems, the video signal controls only the luminance of the various areas of the image. In color systems, it is necessary to control both the luminance and the chrominance of the picture elements.
COAXIAL CABLE
Coaxial cable, or coax, is an electrical cable with an inner conductor surrounded by a flexible, tubular insulating layer, surrounded by a tubular conducting shield. The term coaxial comes from the inner conductor and the outer shield sharing the same geometric axis. Coaxial cable was invented by English engineer and mathematician Oliver Heaviside, who patented the design in 1880.
Coaxial cable is used as a transmission line for radio frequency signals. Its applications include feedlines connecting radio transmitters and receivers with their antennas, computer network (Internet) connections, and distributing cable television signals .
CABLE TV HEADEND
A cable television headend is a master facility for receiving television signals for processing and distribution over a cable television system. The headend facility is normally unstaffed and surrounded by some type of security fencing and is typically a building or large shed housing electronic equipment used to receive and re-transmit video over the local cable infrastructure. One can also find head ends in power line communication (PLC) substations and Internet communications networks.
[attachment=26577]
Coaxial cables have been used to construct the cable TV distribution network. At the beginning, a cable TV distribution network was very simple and consisted of coaxial cables connecting an antenna on a hillside to many homes that did not get good reception using their rooftop antennas. To compensate for signal losses caused by branch splitting and cable attenuation, TV signals picked up by the hillside antenna are usually enhanced by a wide-band amplifier, whose bandwidth covers TV channels of interests, raising the signal level by 10 to 25 dB .
In-House Wiring Configuration
In a new construction, coaxial cables are connected from a central location near the TV signal source, be it a cable TV or a satellite dish, to every room where an in-house TV wiring connection should be available. This configuration forms a star topology.
A multiport splitter is located at the center of the star. Depending upon the number of rooms to be served, some times an amplifier is inserted between the video source and the multiport splitter to raise the signal level, compensating signal losses caused by branch splitting.
Hybrid Fiber Coaxial and Tree Branch Distribution Plant
The general arrangement of the cable TV hybrid fiber coaxial and tree branch distribution network connecting all subscribers. TV signals are originated from the head end. Two-way services such as cable modem for Internet access and POTS are also terminated and managed at the head end .
A dual optical ring is used to connect all head ends and hubs over the SONET and ATM infrastructure for delivering and exchanging digital programs. AM fiber links are extended to a number of fiber nodes. From each fiber node, a few coaxial trunk cables, each of which serves a few hundred subscribers, are further extended to neighborhoods. Subscribers are connected to trunk cables through drop coaxial cables.
DISH ANTEENA
A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or parabolic dish.
The main advantage of a parabolic antenna is that it is highly directive; it functions similarly to a searchlight or flashlight reflector to direct the radio waves in a narrow beam, or receive radio waves from one particular direction only.
RECEIVER
The equipment used to receive the transmitted modulated radio-frequency signals and produce synchronized visual images and sound. The radio-frequency portion operates on the superheterodyne principle.
Television receivers designed to produce images in full color are necessarily more complex than those designed to produce monochrome images only. In monochrome systems, the video signal controls only the luminance of the various areas of the image. In color systems, it is necessary to control both the luminance and the chrominance of the picture elements.
COAXIAL CABLE
Coaxial cable, or coax, is an electrical cable with an inner conductor surrounded by a flexible, tubular insulating layer, surrounded by a tubular conducting shield. The term coaxial comes from the inner conductor and the outer shield sharing the same geometric axis. Coaxial cable was invented by English engineer and mathematician Oliver Heaviside, who patented the design in 1880.
Coaxial cable is used as a transmission line for radio frequency signals. Its applications include feedlines connecting radio transmitters and receivers with their antennas, computer network (Internet) connections, and distributing cable television signals .
CABLE TV HEADEND
A cable television headend is a master facility for receiving television signals for processing and distribution over a cable television system. The headend facility is normally unstaffed and surrounded by some type of security fencing and is typically a building or large shed housing electronic equipment used to receive and re-transmit video over the local cable infrastructure. One can also find head ends in power line communication (PLC) substations and Internet communications networks.