How Cable Modems Work

If you live in an area where you get cable TV, you may want to invest in a cable modem for your high-speed Internet access. If you do here is a guide as to how it works:

 

·        The Space Factor: Coaxial cable can carry hundreds of megahertz of signals and more. The way cable TV works is that each signal from various channels are given a chunk of 6-MHz. This signal is then sent to your house by way of the cable. The cable modem can work on the same line because it just adds an extra 6-MHz.

·        The equipment: In order to transmit data from the home to the central office, a cable modem is used to send the data and a cable modem termination system (CMTS) is used on the receiving end at the central office. The cable modem consist of the following:

o       A tuner – The tuner receives the modulated digital signal and passes it to the demodulator.

o       A demodulator – The demodulator takes the signal and converts it to a signal that the analog-to-digital (A/D) converter can process. The A/D converter then takes the signal and turns it into ones and zeroes.

o       A modulator – The modulator does the opposite of the demodulator.

o       A media access control (MAC) device – The MAC acts as an interface between the hardware and the software.

o       A Microprocessor – The internal microprocessor picks up the MAC functions of the MAC module.

·        The Termination System: The cable company takes the signal from the cable modem and routes it to an ISP so connection to the internet is possible.