What Is A Cable Modem?
A cable modem is an external hardware device that allows users to access the Internet via the cable television network. The cable modem transmits and receives data from the cable network, while traditional analog cable television systems only receive data.
Cable modems originally used a protocol called CPE that downloaded information on the cable network but would transmit data across telephone lines. This was called one-way cable and died as a viable technology very quickly. Two-way cable uses an RF return path, meaning that data is uploaded and downloaded via the cable network. This is the service that is available today through Comcast, Time Warner, Charter, Cox, and other major Cable Internet service providers.
CPE was replaced in 1997 by DOCSIS 1.0 which stands for Data Over Cable Service Interface Specification. This international standard is in use today and allows two-way data communication at a much higher rate than CPE. DOCSIS 2.0 was released in 2002 to further increase transfer speeds and make services such as VoIP a reality.
Cable modems currently offer one of the fastest residential Internet services available. DSL is not currently able to match cable for it's top speeds, so DSL Internet providers have turned to fiber optics as a means to keep pace with cable Internet.