Internal Functions Of Cable Modem

Cable Modems one of the newest technologies that have been introduced in the world of Internet. Cable data networks integrate the elements necessary to advance beyond dial up modem technology. Cable modems make optimum use of the unutilized bandwidth of the cable TV service. They provide such measures as privacy, security, data networking, Internet access, and best quality service features. The term generally refers to a modem that operates over the ordinary cable TV network cables. Cable modem technology offers high-speed access to the Internet and World Wide Web services.

Actually, the term "Cable Modem" can be ambiguous as a Cable Modem works more like a Local Area Network (LAN) interface than as a modem. Your cable Modem needs to be connected to the TV outlet for your cable TV. On other end, the cable TV operator connects a Cable Modem Termination System (CMTS) at their end. The network architecture enables a user cable modem to connect to a CMTS that in turn connects to a regional data center for access to Internet services. Thus, through a system of network connections, a cable data network is capable of connecting users to other users anywhere in the global network. Let us now see working of the various parts of the cable modem.

One of the most important devices is a tuner. The tuner connects to the outlet of the CATV. The tuner receives a digital signal from the modulator and then passes this on to the demodulator. The modulator in cable modems is used to convert digital information into a series of analog signals. They contain a QAM, like demodulators. However, instead of having an A/D converter, modulators have a D/A converter. This converts the information from digital form to analog form. On other hand, demodulator usually contains a device called quadrature amplitude modulation (QAM). QAM takes these analog signals and encodes information in them by varying their amplitudes and their phases. This signal goes through the A/D converter to be converted into digital form, in a series of 0s and 1s. The demodulator consists of an error correction unit that checks for errors, as well as a MPEG frame synchronizer that makes sure groups of data stay together and in order. The modulator, like the demodulator, contains an error correction module to check for errors. Both modulator and demodulator perform two most important function of the cable modem. One, the usual data conversion and transmission and other is to preserve the integrity f the data while transmitting the data.

Another important part is called the MAC or The Media Access Control mechanism. This part is positioned between the upstream and downstream paths. MAC act as an interface between hardware and software portions of the networks. Usually, MAC need the help of the cable modem's central processing unit to carry out all of their responsibilities. This leads us to the microprocessor of a cable modem that usually help MAC perform some of its function apart from processing tasks.