What is ADSL?
Asymmetric Digital Subscriber Line, or ADSL for short, is a form of digital data communications technology using the same copper telephone lines conventional voice-band modems do but with much greater bandwidth and faster data transmission. ADSL makes this possible by transmitting over frequencies other than those used by voice telephone calls. A low-cost ADSL ADSL “modem” is connected to a user’s existing telephone line with a separate Ethernet cable connected to their computer (or in the case of a wireless modem, no cables are used). Users can use both ADSL Internet services and voice calls concurrently through use of a DSL filter/splitter. In this case the filter/splitter is connected to the user’s telephone wall jack and both ADSL modem and telephone are connected to it via separate jacks.
ADSL is ideal for range of Internet activities like email, web browsing, chatting, gaming, and overall casual surfing. ADSL speeds typically vary anywhere on average from 256 kilobytes-per-second (Kbps) up to 10 megabytes per second (Mbps) on the down-link, with the up-link being but a fraction of this. It is for this very reason why ADSL is “asymmetric”, as most users do not require the same uplink throughput as they do on the down-link hence the bandwidth asymmetry. As an example, a request for a YouTube video may only require a few bytes to be sent to the hosting web server, whereas the requested video could very well require dozens of megabytes to be downloaded to the user’s PC.
ADSL-based Internet access is fairly economical, but typically requires a one- or two-year contract for service (actual terms depend on the local service provider). As an incentive, ADSL providers tend to give away an ADSL modem to customers free of charge. ADSL is faster than dial-up, can work anywhere a standard phone line exists (as opposed to cable modem which requires a co-axial line connected to a cable television company), and doesn’t suffer from high latency that wireless and satellite networks do.
One of the biggest drawbacks to ADSL is that its over speed and performance depend on the user’s proximity to the provider’s hub and/or central office. The closer one is, the faster the connection will be. The ideal range for ADSL use is within a two mile radius. People living several kilometers away many not even be eligible for the service.
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