Data Communications Networking Devices - 4th Ed.pdf

496 _________________________________ WIDE AREA NETWORK TRANSMISSION EQUIPMENTbecoming in effect a workstation on a LAN that can represent up to 200 miles ofCATV cable infrastructure.In addition to requiring an Ethernet adapter card in each PC that will beconnected to the cable modem, the upgrade of CATV plant to support datatransmission via cable modems requires several additional components. Theseinclude a frequency converter, con®guration server and router. Figure 4.75illustrates their use on a CATV cabling infrastructure to provide subscribers with abidirectional 10 Mbps operating capability using the LANcity LCP.Figure 4.75CATV plant components supporting data transmissionFrequency converterThe use of a frequency converter is required to change the reverse directionfrequency to the forward direction frequency and vice versa. This conversion isrequired to enable one user to communicate with another as one channel provides atransmission path while a second channel is used for data reception. Thisconversion occurs at the headend and is limited to the 6 MHz channels used fordata, ignoring other cable services. The LANcity product that performs frequencyconversion is marketed as the LANcity TransMaster LCT).