Cisco 450 Руководство по установке оборудования - Страница 16

Просмотреть онлайн или скачать pdf Руководство по установке оборудования для Шлюз Cisco 450. Cisco 450 37 страниц. Voice gateway

Interference Considerations

Note

Typically, a 26 AWG wire is equal to 81.6 ohm/Kft and 24 AWG wire is equal to 51.3 ohm/Kft.

Interference Considerations

When you run cables for any significant distance in an electromagnetic field, interference can occur between

the electromagnetic field and the signals on the cables. This has two implications for the installation of terminal

plant cabling:

• Unshielded plant cabling can emit radio interference.

• Strong electromagnetic interference (EMI), especially as caused by lightning or radio transmitters, can

If you use twisted-pair cables with a good distribution of grounding conductors in your plant cabling, emitted

radio interference is unlikely.

If you have cables exceeding recommended distances, or if you have cables that pass between buildings, give

special consideration to the effect of lightning strikes or ground loops. If your site has these characteristics,

consult experts in lightning suppression and shielding. The electromagnetic pulse caused by lightning or other

high-energy phenomena can easily couple enough energy into unshielded conductors to destroy electronic

devices.

Most data centers cannot resolve such infrequent, but potentially catastrophic problems without pulse meters

and other special equipment. Take precautions to avoid these problems by providing a properly grounded and

shielded environment and by installing electrical surge suppression.

If you remove any module, you must either install a module in its place or install a cover plate over the opening.

All module openings must be either occupied or covered to prevent electromagnetic interference.

For advice on the prevention of electromagnetic interference, consult experts in radio-frequency interference

(RFI).

Cisco 450 Voice Gateway Hardware Installation Guide

destroy the EIA/TIA-232 drivers and receivers in the Cisco VG450 Voice Gateway.

Planning Your Installation