Broadband vs. Dial-Up

Methods that home computer users can use to connect to the Internet can be divided into two categories: Dial-up and broadband.

Dial-up

Dial-up is the method probably most familiar to folks who have been using the Internet for some time. Dial-up refers to using a device connected to the computer, the modem, which is plugged into the household telephone line. The modem can either be internal or external to the computer. If it is internal, it can be a card that plugs into an expansion slot on the motherboard, or it can just be a chip on the motherboard itself that has an external jack for the telephone line. If it is external, it can be a box sitting on the desk that again has a jack connecting to the telephone line, as well as a cable that connects to the computer's serial port.

To connect to the Internet using dial-up, the user must enter the telephone number of their Internet Service Provider (ISP) into the modem software, allowing the modem to "dial-up" the ISP and establish a connection.

Dial-up connections and modems have been around far longer than the Internet itself, dating from the invention of the modem by Bell Labs in 1962. The function of a modem is to convert a digital signal from a computer into an analog signal that can be carried on a telephone line. Obviously, there must also be a modem on the receiving end to convert the analog signal on the telephone line back to the digital signal the computer can use. The name "modem" reflects this function, as it is a contraction of the words "MODulate - DEModulate."

The first modem had a data transfer rate of 300 bits per second (bps). Over the years, technology has improved on this speed in a regular progression. We have passed through 1200 bps (or 1.2 Kilobits per second (Kbps)), 2.4 Kbps, 4.8, 9.6, 14.4, 28.8, finally culminating in the mid-90s at 56 Kbps. This is the practical limit for modem technology, due to the electrical characteristics of telephone lines. The only modern modems available today are generally 56 K models, although this does not guarantee the user will see transmission rates anywhere near this speed. The transmission speeds achieved depend on several factors, including line quality and amount of noise on the line. If the line is noisy, the modems on either end will negotiate downwards until they get to a speed they can transmit and receive on reliably. This negotiation is the familiar static noise we hear at the beginning of a dial-up session.

Currently, dial-up connections are generally the most inexpensive way to access the Internet, but broadband costs are dropping and becoming more competitive every day. Generally, the most compelling reason to use dial-up over broadband is due to lack of available broadband alternatives. Also, dial-up can be an excellent alternative to travelers who have accounts with nationally based ISPs, and who can use local phone numbers from wherever they are to access the Internet. However, as more and more hotels start offering free or low cost broadband Internet access, this becomes less of a factor.

Broadband

The definition of broadband is rather flexible, but in practical terms it means "anything faster than dial-up." The most lenient definitions I have seen have broadband starting at about 100 Kbps, although I have seen some that insist it's not true broadband until data rates in the Megabits per second (Mbps) are achieved. Unlike dial-up, there are several different methods of implementing broadband technology. The ones most likely to be seen by home users are DSL, cable modem, and satellite.

DSL

DSL stands for Digital Subscriber Line. It is a technology that can be implemented over a user's existing telephone line. DSL uses different frequencies than voice communications does, so the same phone line can carry both a phone conversation and an Internet session at the same time. Line speeds available over DSL generally range from 256 Kbps to 1.5 Mbps. DSL requires a special interface, a DSL modem, which must be connected between the telephone connection in the wall and a network interface card in the computer. DSL is an always on technology, meaning the connection is always established as long as the modem and the computer are on. This makes the need for a firewall on the connection of utmost importance, to prevent hackers from finding and exploiting the connection. The major shortcoming of DSL is its distance limitation. DSL can only travel over about 5,000 feet of wire before attenuation causes the signal to fade out, so users must be located within about a mile of the local telephone equipment station.

Cable Modem

Cable modem is fast becoming the technology of choice for those to whom it is available. The Internet Service Provider is the local cable company, who transmit the Internet session over the same coaxial cable they use to transmit television signals. The cable modem is a separate interface that connects to the cable coming into the house, and which is also connected to a network interface card in the computer. Cable modems have a higher session speed than DSL, generally up to 10 Mbps, and are also an always-on technology. One possible downside to cable modems is that it is a shared technology, meaning that all the users in a neighborhood are sharing the same connection to the cable facility. This could result in a slowdown of service if all the neighbors start downloading huge files at the same time, but currently this doesn't seem to be a problem.

Satellite

Satellite Internet services provide an option for users who do not have access to cable modems, but who want something fast than dial-up. These services are provided by the same companies that provide satellite television, such as DirecTV or Dish Network. This service allows a download link to your computer at about the same speeds as cable modems. However, since most dishes cannot currently send an uplink, a telephone line to the service must be used for uplink commands. The telephone line generally runs around 256 Kbps. So while the satellite connection works really well for downloading information, it is a lot slower when uploading. Another major disadvantage of the satellite is due to the latency inherent in satellite communications. Due to the distance between the Earth and the satellite, there is a two second lag between issuing a command and receiving information back. If you are just downloading a large file, this is no problem. You issue the download command, wait two seconds, and the file starts coming at the full speed of the service, and maintains that speed until the file is finished. However, this can make regular web browsing something of a pain. Many web pages consist of many small files, some containing text, some pictures, and so on. When downloading a web page of this type, the connection will have to request the file, wait two seconds and get it, request the next file, wait another two seconds, and so on. So if you connect to a web page which has, for example, 50 files on it, which is not unusual, you will have an extra 100 seconds of delay time, or it will take about two minutes for the page to fully load. This can make casual browsing rather cumbersome.