In addition to wired keyboards, there are also wirelessly operating infrared and radio keyboards. Radio keyboards, radio keyboards, work with short-range radio using SRD technology and transmit their signals in license-free ISM bands.
As for the transmission bands, these are the CB band at 27 MHz or the ISM bands at 40 MHz, 433 MHz, 868 MHz and 2.4 GHz, in which most radio keyboards operate. All radio technologies do not require line-of-sight between the keyboard and computer and can bridge distances of a few meters. However, wireless keyboards require their own power supply.
Since the ISM bands mentioned are not available in all continents and regions, country-specific versions with the corresponding license-free frequencies are produced for such wireless keyboards. In addition, interference of wireless keyboards transmitting close to each other can occur. An alternative is WirelessUSB, which operates in the ISM band at 2.4 GHz. This frequency band is available worldwide and has range advantages. This means that corresponding keyboards can also be used in conjunction with set-top boxes.