NEC SV8500, Руководство пользователя

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VOL.1-170
CHAPTER 3 INSTALLATION DESIGN
• Types of propagation
There are two major types of radio wave propagation:
1. Line-of-sight propagation
2. Propagation beyond the horizon.
As opposed to a cellular phone, consideration must be given to the line-of-sight propagation character-
istics, where a ZT can be seen directly. As for the propagation beyond the horizon, radio waves travel
through walls, ceilings, partition on the same floor, or another floor for a Wireless system used on pri-
vate premises with a very small service area.
2.2 Installation of the Zone Transfer (ZT)
How to install the ZT and precautions made when mounting it is explained as follows:.
a. The ZT is a communication device that sends a weak signal as radio waves. It should not be installed
near and around equipment or an environment listed below, to ensure speech quality and various kinds
of control operations. Care must be taken.
Indoor Installation
Do not install around equipment capable of emitting noise (high frequency electric waves) such as
a Wireless apparatus, television set, radio set, fluorescent lightening, and microwave oven.
Line-of-sight propagation
a. Free spaces propagation: • When a distance doubles, prop-
agation loss increases by 6 dB.
• When a wavelength is halved,
propagation loss increases by 6
dB.
Plane earth propagation: When a distance doubles, propaga-
tion loss increases by 12 dB (it is
wavelength-independent).
b. Propagation beyond the horizon
Multiple wave propagation: Propagation where numerous
reflected and diffracted waves are
received. (the original mobile
communications use this type of
propagation.)