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» Wireless (RF) Data Networks
What is spread spectrum radio ?
Spread spectrum radio is used commercially to enable wireless (i.e.
without wires) data and voice communications within a limited area
without a need for radio licences or cellular airtime charges. Originally
developed for secure and resilient military communications, data
transmissions are made within a "spread" of different
frequencies. This approach has a number of benefits: from a technical
point of view it means that there is very little chance of data
not getting through or being corrupted; also, spread spectrum installations
do not require any form of relicensing.
A spread spectrum radio network is created by carefully positioning
a number of radio transceivers (called access points). The access
points are wired to the host networking system and create a radio
data network similar to a cellular network, but on a much smaller,
local scale. Portable computing devices can then communicate, via
the access points, with their host network, transmitting and receiving
data in "real time". For instance, a sales order processing
function can communicate the picking requirements direct to a forklift
truck-mounted terminal in the warehouse. Similarly, that terminal
can transmit its activities to stock control and purchasing. Of
course you need appropriate application software to do all this
over the wireless data network.
Spread spectrum wireless networks can support voice as well as data
communications; in addition to RF enabled scanner terminals, a network
can host phones capable of transmitting and receiving voice data.
This capability is particularly attractive for environments where
normal cellular communications are not permitted, for instance in
The first stage in establishing a spread spectrum wireless network
is to commission a site survey. The survey will establish the suitability
of the site for an RF network installation and will identify what
number - and most importantly the positions - of the access points
needed to give the necessary coverage. The survey will also enable
consideration of which type of spread spectrum technologies (direct
sequence or frequency hopping - the differences are fairly technical!)
will be most appropriate.
There is a wide range of portable data terminals to suit specific
application demands. These range from scanner enabled terminals
through to ruggedised terminals for arduous industrial environments,
and hands-free "wearable" systems using ring scanners.