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Access Communications System (PACS) is a type of wireless
telephone network compatible with telephone sets, answering
machines, fax machines, and computers. A PACS can be used
like a local area network (LAN) with voice capability and
can be part of a larger network or can be connected into
the telephone system.
A typical PACS resembles
a cellular telephone network in miniature. It contains numerous
radio port control units (RCPUs), each of which is the equivalent
of a cellular repeater, but with a shorter communications
range, linking subscriber sets within a radius of a few
hundred feet. RPCUs are located on utility poles, atop buildings,
and in other unobtrusive places that offer good coverage
for several hundred feet in all directions. RPCU transmitter
power is limited to 800 milliwatts. The operating frequency
is in the UHF (ultra-high-frequency) radio range at 1.9
GHz.
The subscriber sets in a
PACS can be fixed, mobile, or portable. Voice subscriber
sets use 32 Kbps or 64 Kbps digital speech coding. Computer
web designing
company modems can be supported at speeds of up to 28.8
kbps or 57.6 kbps, respectively. Transmitter output power
is limited to 200 milliwatts, but is often much less, on
the order of a few tens of milliwatts. This low power level
minimizes the likelihood of electromagnetic interference
(EMI) to other electronic devices that might be located
near the subscriber set.
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