Modems

Broadband System – P
Satellites are spaced every 2nd degrees above earth
"C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz

"L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz

TV TRANSMITTER

Headend

Cable area
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DOCSIS, QPSK, QAM signal and Cable Modem System.

Understanding DOCSIS Operating System.

A Cable system operating with Cable Modems required,
•A bi-directional HFC or CATV system. •A Cable Modem Termination System at the Headend or Hub site. •A 100 BaseT or better connection to Internet or Servers. •A 6 MHz of 64 or 256 QAM data channel operating from: 88 to 870 MHz. •A 3.2 MHz of QPSK or 16 QAM operating between 16 to 40 MHz on the return section of the system for DOCSIS 1.0. •At least one Cable Modem installed at a customer on the system.

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Understanding DOCSIS Operating System.

One standard that will be repeated very often in the following lecture; DOCSIS(™)

Data Over Cable Service Interface Specification.
DOCSIS specifications can be; DOCSIS 1.0, 1.1, 2.0 and 3.0
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Understanding DOCSIS Operating System.

One other standard that will be repeated very often in the following lecture; CMTS.

Cable Modem Termination System
The above unit is what controls all the data to and from all Cablemodem on the HFC system.
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Understanding DOCSIS Operating System.
The DOCSIS services, Data Over Cable Services Interfaces Specifications was developed by CableLabs and approved by the ITU. It also defines interface requirements for cable modems involved in high speed data distribution (both MPEG and IP data) aver cable system networks. Other devices that recognize and support the DOCSIS standard include HDTV's and Web enabled set-top boxes for regular televisions. There are two key components in the DOCSIS architecture: Cable modem (CM) which is located at the customer premise, and Cable Modem Transmission System (CMTS), which is located at the Headend of service provider s and used to aggregated traffic from