Cisco Systems UBR904 manual AC Power, Wiring and Cabling, Interference Considerations

Site Requirements

AC Power

The AC-input power supply in the Cisco uBR904 cable modem uses a power factor corrector that allows the Cisco uBR904 cable modem to operate on input voltage and frequency within the ranges of 100 to 240 VAC and 50/60 Hz.

Refer to Table 1-1in the chapter “Product Overview” for system power specifications, including input voltage and operating frequency ranges.

Wiring and Cabling

Following are guidelines for setting up the wiring and cabling at the installation site. When planning the location of the Cisco uBR904 cable modem, consider the issues of electromagnetic interference (EMI), coaxial cable quality, and distance limitations for signaling, as described in the following sections.

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 plant wiring:

•Bad wiring practice can result in radio interference emanating from the plant wiring.

•Strong EMI, especially when it is caused by lightning or radio transmitters, can destroy the signal drivers and receivers in the Cisco uBR904 cable modem, and can even create an electrical hazard by conducting power surges through lines and into equipment.

(Review the safety warnings in the section “Safety with Electricity” earlier in this chapter.)

Note To predict and remedy strong EMI, you might also need to consult experts in radio frequency interference (RFI).

2-6Cisco uBR904 Cable Modem Installation and Configuration Guide