Table of Contents

Coaxial Cable Specifications

The coaxial cable used to connect the Cisco uBR7200 series universal broadband routers at the headend should be very high-quality cable.

Cisco recommends that you use a headend-grade coaxial cable or a quad-shield coaxial cable with a minimum of 60% + 40% braid and double foil insulation to connect the cable modem cards to the HFC network. The center conductor must be straight and extend 1/8 inch (3.2 mm) beyond the end of the connector, and the connector should be securely crimped to the cable. The following cables are recommended:

• RG-59---0.034 inch (0.86 mm) center conductor diameter

• RG-59/U---0.0226 inch (0.57 mm) center conductor diameter

• RG-6---0.041 inch (1.05 mm) center conductor diameter

Note All three of the coaxial cables listed can be used to connect a Cisco cable modem card to the HFC network; however, the consistent use of RG-59 cable is preferred. If you connect an RG-59 cable to a cable modem card that was previously connected using RG-6 cable, the difference in the center connector diameter might cause intermittent connectivity loss.

If you use different types of coaxial cable, the following problems can appear:

• Co-channel interference---If signals at the same frequency are carried on long, parallel runs of coaxial cable, interference can occur between the signals. Higher quality cable helps to prevent this with better shielding. Co-channel interference is seen as hum or patterns in analog video channels and intermittent data loss in digital channels.

• Damage to Cisco uBR7200 series cable modem card connectors---Cable modem card connectors are designed for RG-59 or RG-6 cable and connectors. Larger cables can damage the connectors.

• High signal return loss---High quality cable and correct connectors help to ensure an optimal return loss of 16 dB or more.

Note Refer to "Connecting and Configuring the Cable Headend," for additional configuration and site requirement information related to the setup of the analog RF signal and digital data.

Posted: Tue Mar 28 08:45:12 PST 2000
Copyright 1989 - 2000©Cisco Systems Inc.