DOCSIS Figure 1

A DOCSIS-compliant cable modem receives its data over unused 6-MHz video channels within the normal cable spectrum. Upstream traffic is carried back to the system headend in the 5-to-45-MHz sub-split band. To ensure that the modem will operate properly and not interfere with other units, both the downstream receiver and upstream modulator/transmitter operate under the control of the BCM3220, or other DOCSIS-compatible MAC.