15-05-2012, 10:31 AM
Cable Modem
[attachment=22043]
INTRODUCTION
The term ‘Cable Modem’ is quite new and refers to a modem
that operates over the ordinary cable TV network cables. Basically
you just connect the Cable Modem to the TV outlet for your cable
TV, and the cable TV operator connects a Cable Modem
Termination System (CMTS) in his end (the Head-End).
Actually the term "Cable Modem" is a bit misleading, as a
Cable Modem works more like a Local Area Network (LAN)
interface than as a modem.
Cable modems allows consumers access to the Internet at
higher speeds and at a fraction of the time it takes traditional
telephone modems.
This is true for two reasons:
1) Broadband networks make the connection up to a hundred
times faster
2) The service is "always on," meaning customers get the
information they want, when they want it.
101seminartopics.com 2
Unlike telephone modems, cable modems allow consumers to
keep their telephone lines open for voice conversations.
IMPORTANT TERMS
A short list of some of the technical terms and acronyms that
you may come across in trying to understand the cable modem
world.
CATV: Community Antenna Television or Cable TV system. Can be
all coaxial or HFC (Hybrid Fiber Coax) based.
Cable modem (CM): Client device for providing data over a cable
TV network. Read all about it here.
Channel: A specific frequency and bandwidth combination. Used
in this context about TV channels for television services and
downstream data for cable modems.
CMTS: Cable Modem Termination System. Central device for
connecting the cable TV network to a data network like the
internet. Normally placed in the headend of the cable TV system.
CPE: Customer Premises Equipment. Used to describe the PC
and/or other equipment, that the customer may want to connect
to the cable modem.
DHCP: Dynamic Host Configuration Protocol. This protocol
provides a mechanism for allocating IP addresses dynamically so
that addresses can be reused. Often used for managing the IP
101seminartopics.com 3
addresses of all the cable modems in a cable plant and the PC's
connected to the cable modems.
DOCSIS: Data Over Cable Service Interface Specification. The
dominating cable modem standard. Defines technical
specifications for both cable modem and CMTS.
Downstream: The data flowing from the CMTS to the cable
modem.
Downstream frequency: The frequency used for transmitting data
from the CMTS to the cable modem. Normally in the 42/65-850
MHz range depending on the actual cable plant capabilities.
[attachment=22043]
INTRODUCTION
The term ‘Cable Modem’ is quite new and refers to a modem
that operates over the ordinary cable TV network cables. Basically
you just connect the Cable Modem to the TV outlet for your cable
TV, and the cable TV operator connects a Cable Modem
Termination System (CMTS) in his end (the Head-End).
Actually the term "Cable Modem" is a bit misleading, as a
Cable Modem works more like a Local Area Network (LAN)
interface than as a modem.
Cable modems allows consumers access to the Internet at
higher speeds and at a fraction of the time it takes traditional
telephone modems.
This is true for two reasons:
1) Broadband networks make the connection up to a hundred
times faster
2) The service is "always on," meaning customers get the
information they want, when they want it.
101seminartopics.com 2
Unlike telephone modems, cable modems allow consumers to
keep their telephone lines open for voice conversations.
IMPORTANT TERMS
A short list of some of the technical terms and acronyms that
you may come across in trying to understand the cable modem
world.
CATV: Community Antenna Television or Cable TV system. Can be
all coaxial or HFC (Hybrid Fiber Coax) based.
Cable modem (CM): Client device for providing data over a cable
TV network. Read all about it here.
Channel: A specific frequency and bandwidth combination. Used
in this context about TV channels for television services and
downstream data for cable modems.
CMTS: Cable Modem Termination System. Central device for
connecting the cable TV network to a data network like the
internet. Normally placed in the headend of the cable TV system.
CPE: Customer Premises Equipment. Used to describe the PC
and/or other equipment, that the customer may want to connect
to the cable modem.
DHCP: Dynamic Host Configuration Protocol. This protocol
provides a mechanism for allocating IP addresses dynamically so
that addresses can be reused. Often used for managing the IP
101seminartopics.com 3
addresses of all the cable modems in a cable plant and the PC's
connected to the cable modems.
DOCSIS: Data Over Cable Service Interface Specification. The
dominating cable modem standard. Defines technical
specifications for both cable modem and CMTS.
Downstream: The data flowing from the CMTS to the cable
modem.
Downstream frequency: The frequency used for transmitting data
from the CMTS to the cable modem. Normally in the 42/65-850
MHz range depending on the actual cable plant capabilities.