Info about Modems
What are the cable modems and their types of services?
A device that allows your computer to access the Internet through dedicated broadband transmission networking services by means of your home cable TV (CATV) connection.
Cable modems modulate and demodulate analog signals like regular modems, but for transmission over broadband video services instead of telephone voice services. A cable modem can be internal or external and can interface with the coaxial cable connection at the user's end and the Cable Modem Termination System (CMTS) at the cable provider's head office.
Cable modem and Asymmetric Digital Subscriber Line (ADSL) are competing technologies for bringing high- speed broadband Internet services to homes and businesses. Cable modems offer downstream speeds of 10 megabits per second (Mbps) and higher, but competing technologies, lack of standards, and implementation costs have slowed widespread deployment and use of this technology.
There are two basic types of cable modem services:
• One-way cable modems:
These are used by unidirectional cable service providers. Most cable TV services are designed to carry information in one direction only-from the broadcaster to the customer premises. With one-way cable modems, the customer uses a regular telephone modem to send information to the cable company but uses the cable TV system with cable mode to receive signals from the company. The telephone modem handles all upstream communication, and the cable modem handles all downstream communication. One-way cable modems are typically cards installed inside a subscriber's computer.
• Two-way cable modems:
These require that the broadcasting cable company has converted its cabling and repeater infrastructure for bidirectional communication. Two-way cable modems are typically external devices connected to a network interface card (NIC) that is installed in the subscriber's computer. The cable modem is used for both upstream and downstream communication in this configuration. Most cable companies currently have initiatives under way to make such a conversion, but it requires a large capital investment. Therefore, it will be several years before these systems become widely available.