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 hospitals.

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.