Hybrid fiber coax (HFC), a network featuring optical fiber from a central office to a neighborhood and standard coax cable to individual homes. It incorporates both fiber optic transmission components and copper coaxial transmission components and now it is a way of delivering video, voice telephony, data, and other interactive services. HFC is also called as the second generation of CATV systems. It offers high-speed backbone data interconnection lines (the fiber portion) to interconnect end user video and data equipment. Nowadays, HFC system (as shown in the following picture) is fast becoming a major transmission vehicle for interactive broadband access to the World Wide Web, CATV, and other multimedia applications.
- Less maintenance costs due to fewer amplifiers required. Also needs less electricity than coaxial.
- Reliable, immune to noise and almost non-existent attenuation.
- High bandwidth capabilities, increased from traditional CATV network (up to 330MHz or 450MHz) to 750MHz with HFC.
- Has ability to adapt to new services such as voice, data or video without changing existing operational parameters.
- Lighter weight and thinner than copper cables with the same bandwidth so that much less space is required in underground cabling ducts and easier for installation engineers to handle.
- Much more difficult to tap information from undetected; a great advantage for banks and security installations. Immune to Electromagnetic interference from radio signals, car ignition systems, lightning etc. Can be routed safely through explosive or flammable atmospheres.
- Can support Cable telephones, increased number of CATV channels (to over 200), a direct infrastructure to new Digital TV standards which assume that networks will use HFC backbones and ATM services.
- No need to dial-up or tie up a phone line as it uses a separate connection, Cable Internet has constant connectivity.
- More expensive than Coaxial Cable, especially costly to rural subscribers due to long cables required.
- Due to the huge number of users that a fibre will support, a train derailment, earthquake or other traumatic even can have catastrophic proportions.
- Optical fibres cannot be joined (spliced) together as easily as copper cable and requires additional training of personnel and expensive precision splicing and measurement equipment.
- Asymmetrical, not based on new interactive multimedia.
- As more subscribers use the network. Speed of transmissions also decrease
HFC were once thought to be the way of the future but this idea is being questioned as there are increasing technological advances. Asynchronous Digital Subscriber Line (ADSL) is an alternative which Service Providers and consumers are considering, placing it in competition with HFC. ADSL gives access to the Internet via the already existing telephone lines at a different frequency to telephone communication. This means that both the telephone and computer can receive signals at the same time with little or no interference. It is more convenient to use existing telephone lines for ADSL than it is to install a coaxial cable from the street to the home for HFC. This allows ADSL to provide cheaper services and attract more users. Nonetheless, HFC has still been applied widely in some countries. In addition, the appearance of FTTX technology will push optical fiber further into the HFC network. Certainly, in order to adjust to more interactive applications, future HFC network may be continuing improving.
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