Don's Home Technology HFC - Hybrid Fiber/Coax | Contact |
Under Construction. Hybrid fiber-coaxial systems (HFC)allow Cable TV (CATV) systems to be updated to support phone service and internet access as well as video. They use fiber from a head end system to fiber nodes in local neighborhoods and use coax cable (the same as that in place for CATV in many cases) from there to the home. A set-top box/Cable modem splits the voice, data and video signals back out to connect to your TV, phone and computer. The coax piece can be all analog (typically for TV only with no upstream communications), combined analog and digital which will work without a set-top box for TV only but requires a set-top box or cable modem for voice or data or all digital. All digital systems always require a set-top box/cable modem. Some systems broadcast analog video in the 40-550 MHz band and and digital video in the 550-750 MHz band. Each channel takes up 6MHz. 5-42 MHz is used for upstream signaling and voice. 850-1000 MHz is used for upstream signaling (and data?) Set-top boxes/Cable Modems Tellabs CABLESPAN 2300 Universal Telephony Distribution Arris ADC Lucent: QAM 64/256 modulation of data on Data Over Cable Service Interface Specifications (DOCSIS) compliant 6MHz channel with speeds to 38 Mbps QPSK/QAM 16 demodulation of a Time Division Multiplex (TDM) upstream channel with speeds to 10 Mbps NORTEL: Provides separate craft and consumer access compartments specifications Modulation Downstream: 64 / 256 QAM Upstream: QPSK / 16 QAM Frequency range Downstream: 50 to 860 MHz Upstream: 5 to 45 MHz Voice encoding Features G.711 64 kbps toll-grade encoding, and can support G.723, G.726, G.729, or G.728 compression Data protocol support Router (i.e.Passport 8600)CMTS 1500 IP, UDP, TCP, DHCP, TFTP, ARP |