Cisco Systems UBR-3X10 manual Provisioning the Headend, Headend Certification, Headend Wiring

Chapter 2 Preparing for Installation

Provisioning the Headend

Provisioning the Headend

The following sections describe the provisioning required at the cable headend before you install the Cisco uBR 3x10 RF Switch.

Headend Certification

The cable headend plant must pass both analog and digital certification:

•In the United States, the Federal Communications Commission (FCC) mandates certification.

•For international certification, consult with local agencies for certification requirements.

Headend Wiring

This section provides guidelines for setting up the headend wiring and cabling at your site. When planning the location of the new system, consider the distance limitations for signaling, electromagnetic interference (EMI), and connector compatibility, as described in the following sections:

•Interference Considerations

•Distance Limitations and Interface Specifications

Interference Considerations

When wires are run for any significant distance in an electromagnetic field, interference can occur between the field and the signals on the wires. This fact has two implications for the construction of headend wiring:

•Bad wiring practice can result in radio interference emanating from the wiring, ingress noise, co-channel interference, and degraded or erratic universal broadband router performance.

•Strong EMI, especially when caused by lightning or radio transmitters, can destroy the signal drivers and receivers in the Cisco RF switch, and can even create an electrical hazard by conducting power surges through lines and into equipment. (Review the safety warnings in the “Safety with Electricity” section on page 2-3.)

If you use twisted-pair cable in your headend wiring with a good distribution of grounding conductors, the wiring is unlikely to emit radio interference. If you exceed the recommended distances, use a high-quality twisted-pair cable with one ground conductor for each data signal when applicable.

If wires exceed recommended distances, or if wires pass between buildings, give special consideration to the effect of a lightning strike in your vicinity. The electromagnetic pulse caused by lightning or other high-energy phenomena can easily couple enough energy into unshielded conductors to destroy electronic devices. If you have had EMI problems in the past, you might want to consult experts in electrical surge suppression and shielding.

Distance Limitations and Interface Specifications

The size of your networks and the distances between connections depend on the type of signal, the signal speed, and the transmission media (the type of cabling used to transmit the signals). For example, standard coaxial cable has a greater channel capacity than twisted-pair cabling. The distance and rate limits in the following descriptions are the IEEE recommended maximum speeds and distances for

Cisco uBR-3x10 RF Switch Hardware Installation and Cabling Guide

OL-1984-06 2-7