Cabletron Systems FLIU-1, Руководство по установке

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INTRODUCTION
1.3.1 Connectivity
With the Cabletron Systems FreeLINK Wireless LAN System you
can connectEthernet nodes within an wireless 80 meter radius of
the transmitter hub antenna. The FreeLINK system accommodates
up to 62 wireless transceivers, distributed anywhere within the 80
meter operating radius.
1.3.2 Spread Spectrum Technology
Spread spectrum radio communications is a technique used to
transmit radio signals that was originally developed for the
military. It was initially implemented in the 1950s for use in
battleÞeld voice communications because it is extremely difÞcult
to detect that the signal is even present, and if detected, it is even
more difÞcult to decode. It is extremely difÞcult to interfere with,
or jam, the signal.
There are two techniques used in spread spectrum: frequency
hopping and direct sequence. Most wireless network systems
today, including FreeLINK, use direct sequence. Spread spectrum
radio, and FreeLINK in particular, resists detection and
interference, and allows multiple systems to operate in the same
area (hence permitting overlapping FreeLINK hubs). This level of
security far exceeds that of narrow-band transmission and
unshielded twisted pair wire, and uses very little power.
1.3.3 Data Security
Spread spectrum radio transmission techniques were used
exclusively by the U.S. Army since the 1950s for battleÞeld
communications. Spread spectrum has been used since 1967 by the
Israeli military for voice and telemetry communications. The
overriding reason for the militaryÕs extensive use of spread
spectrum is its inherent data security characteristic.