Cable modem

What is a cable modem? It is a type of modem that allows people to access the Internet through their cable television service. The data received is at 1.5 Mbps. This data transfer rate is much more than the 28.8 and 56 Kbps telephone modems and the 128 Kbps ISDN or the Integrated Services Digital Network. This is even faster than the Digital Subscriber Line or DSL telephone service. However it is necessary to remember that cable modem speeds can vary depending the number of people who are accessing at any one time. This is because the bandwidth is divided among all subscribers. What this means is that, the more the number of people who are connected, the less the speed will become.

It is simple to set up a cable modem. It can be easily integrated with a set-top box, which allows the TV to access cable channels. In fact, these days, most cable service providers provide the modem as part of the service.

All the cable modems that are attached to the TV communicate through a Cable Modem Termination System or CMTS at the local cable TV company office. All such modems can receive and send signals only to the CMTS. However, they are unable to do so with other cable modems that are on the line. There are some services that have the upstream signals returned by telephone rather than the cable. In these cases, the cable modem is known as a telco-return cable modem.

Things are however now beginning to change. A cable modem is not just a modem anymore, it has now become a device that modulates and demodulates a signal between an analog network and a digital device. For example, a phone modem can modulate a digital signal from the computer into an analog signal for the phone lines and demodulates the analog phone signal into a digital one.

The first generation of cable modems did the same thing for the cable TV signal. But these days, many cable Internet service providers are migrating towards a fully digital network for everything, including their television signals. This means that cable modems are no more just modems, they are becoming media converters or cable terminal devices.