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Digital Subscriber Line, or DSL as it is commonly known, has long been at the forefront of the high speed broadband revolution. Developed in 1989, DSL was expected to address an anticipated market in Video on Demand that never fully materialized. The technology instead found an application in providing computer users high speed access to the Internet. Essentially the first alternative to unreliable and exceedingly slow dial up access, DSL faces increasing competition from cable, fiber optics, and satellite providers.
How does DSL stack up against the other broadband services? A standard telephone line consists primarily of a pair of copper wires and various jacks located conveniently throughout the home or office. The two wires have the capacity to accommodate much more signal than a phone conversation. The extended range of frequencies or bandwidth allows DSL lines to utilize the additional capacity to transmit data. In the United States, Asymmetric DSL (ADSL) is the standard for broadband transmission.
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The Other Broadband Technologies
Standard cable broadband service uses coaxial cable as its method of delivery. An inner conductor shielded by insulation and then wrapped with a thin metallic foil allows for transmission of signal without significant degradation. Since the signal is only carried between the inner and outer conductors, it is relatively immune to electromagnetic interference and leakage.
Fiber optics cables are the most recent entry into the broadband market on a national scale. These thin strands of glass are approximately the thickness of a human hair and are optically pure. Since the diameter of the cable is smaller and the weight is substantially less than other delivery methods, transmission of digital laser light data pulses over long distances is much faster. Additionally, since the cabling is glass, it does not conduct nor can it generate electricity.
Internet connections via satellite are established through a dish network and are primarily utilized by those living in rural areas where other forms of broadband connectivity are not available. The feed is beamed off geostationary satellites directly to a subscriber’s dish.
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Comparing DSL and Cable
DSL is largely dependent on the distance of the user relative to the location of the provider’s central office or DSL hub. Speed drops off after 9,000 feet and the service is unavailable after distances of 18,000 feet. Additionally, DSL cabling suffers from resistance crosses, load coils, and electromagnetic interference which can create line noise and substantially corrupt the service. The effect of these obstacles often results in much slower transmission speeds for users. Typical download speeds for DSL range from 768 kbps to 7 Mbps for high end packages. The increasing complexity and higher traffic on the Internet may make DSL unacceptable for high activity users, especially with the basic service.
The robust nature of coaxial cabling allows for more reliable service and considerably faster speeds. Cable Internet utilizes TV channel space for data transfer. The available bandwidth is much greater than DSL and therefore transmission speeds are considerably higher. In fact, broadband cable speeds range from 4 Mbps to 6 Mbps for basic packages to 12 Mbps to 16 Mbps for higher end packages. Cable has become extremely accessible with most dwellings built in metropolitan areas within the last 30 years wired for the service.
Competitors often point out additional security risks in broadband cable. Since cable is a shared connection with other area subscribers, there is the potential for a security compromise. However, with the hardware safeguards put in place by the cable provider, coupled with firewall protection from the user, the potential for a security breach is very minimal.
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Fiber Optics and Satellite
Fiber optic cable allows for amazing speeds that will accommodate the most the demanding bandwidth requirements. Since data is transmitted through laser pulses, the distance the information travels becomes almost irrelevant. This allows for download transfer speeds of 10 Mbps for basic service up to an astounding 50 Mbps for premium packages. Additionally, unlike cable or DSL, fiber optic systems have upload speeds of 20 Mbps, substantially faster than competing technologies.
The only significant disadvantage of using fiber optic cable for broadband is the cost and availability. Infrastructure is currently limited and expensive to install, and as a result the accessibility of service is restricted. A smaller base of subscribers requires providers to charge a premium for the service with high-end packages costing as much as $140 per month.
Perhaps the only appealing aspect of satellite broadband is its universal availability. Extreme remote and rural areas that do not have access to other broadband options can utilize a satellite connection to access the internet at reasonable speeds.
Unfortunately, satellite internet is the slowest of the different services. When a subscriber sends a request for a download, the signal must travel 22,300 miles to a satellite and an equal distance back to the service provider where it is finally routed to the subscriber. This 89,200 mile trip creates significant latency and delay. Satellite can deliver speeds up to 3 Mbps which is vastly superior to dial up but slower than all of the hard wired systems
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There is a wide array of often confusing pricing options and packages available in all the different broadband formats. Providers are increasingly creative in bundling phone, television and internet services and establishing price points based on delivery of faster download speeds. These general pricing guidelines are based on internet only service. It important to always check for promotional prices as competition for subscribers is fierce.
§ DSL--$30-$45 per month
§ Cable--$32.95--$59.95 per month
§ Fiber--$49-$139 per month
§ Satellite--$69.99-$199.99 per month
How does DSL stack up against the other broadband services? Once a leading edge technology that offered freedom from the unreliable and slow dial up access, DSL may ultimately suffer the same fate as fiber optics continues to grow in availability and popularity and cable internet prices continue to decline.