The industrial, scientific and medical radio bands, known as ISM, are intended for unlicensed radio communications within a number of frequency bands as laid down by the Electronic Communications Committee. Selection of the appropriate band is influenced by the required bandwidth, which favours higher frequencies, and the transmission range, which is better at lower frequency. A complete array of ISM modules is available covering the available frequency range. Some modules have multiple channels, while others are simple devices intended for short-range communication. Depending upon the application, ISM modules may be standalone units or integrated within the design of electronic equipment. Single-chip radio transceivers can be incorporated within the PCB design and fitted with built-in omni-directional RF aerials. A good way to get started is to purchase an evaluation or development kit to establish the optimum frequency band. These kits are listed under ISM accessories along with power supplies and protective cases. Alternatively, a standalone ISM radio modem could be used. Radio modems are designed for reliable signal transmission over ranges between 1 km and 20 km, depending on their output power and aerial gain. A wide selection of Nordic Semiconductor components is stocked. Other suppliers include Adeunis, Amber Wireless and Microchip.