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Other Cable Services |
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Coaxial cables are capable of bi-directional carriage of signals as well as the transmission of large amounts of data. Cable television signals use only a portion the bandwidth available over coaxial lines. This leaves plenty of space available for other digital services such as broadband internet and cable telephony.
Unlike North America, many cable operators in Europe have already introduced telephone services, which operate just like existing fixed line operators. Broadband internet is achieved over coaxial cable by using cable modems to convert the network data into a type of digital signal that can be transferred over coaxial cable. One problem with some cable systems is the older amplifiers placed along the cable routes are unidirectional thus in order to allow for uploading of data the customer would need to use an analog modem to provide for the upstream connection. This limited the upstream speed to 56k and prevented the always-on convenience broadband internet typically provides. Many large cable systems have upgraded or are upgrading their equipment to allow for bi-directional signals, thus allowing for greater upload speed and always-on convenience, though these upgrades are expensive. Another service being added to many cable systems is cable telephone service. This service involves installing a special telephone interface at the customer's premises that converts the analog signals from the customer's in-home wiring into a digital signal, which is then sent on the local loop (replacing the analog last mile, or POTS) to the company's switching center, where it is connected to the PSTN. The biggest obstacle to cable telephone service is the need for nearly 100% reliable service for emergency calls.
One of the standards available for digital cable telephony, PacketCable, seems to be the most promising and able to work with the Quality of Service demands of traditional analog POTS service. The biggest advantage to digital cable telephone service is similar to the advantage of digital cable TV, namely that data can be compressed, resulting in much less bandwidth used than a dedicated analog circuit-switched service. Other advantages include better voice quality and integration to a VoIP network providing cheap or unlimited nationwide and international calling. Note that in most cases, digital cable telephone service is separate from cable modem service being offered by many cable companies and does not rely on IP traffic or the Internet.Cable television is facing increasing competition from satellite television.
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