Sub-GHz Short Range Devices / ISM-Band (433 MHz and 866 MHz)
SRD, Short Range Device is a term that is applied to a radio device that is designed to operate over a short range. This also implies that the power levels are low and hence the likelihood of interference to other devices is low. Mainly these devices are working in the Sub-GHz ISM band. Cost effectiveness is most often an important decision factor to use this technology, because the total cost of ownership is low. Normally these applications allow peer-to-peer connectivity and have no security features. There are still some devices on the market, which allow unidirectional data transfer only, but most often bidirectional communication is possible nowadays. Target applications for SRD are actually requiring less performance and security and are easier to integrate into end devices. Typical applications with such kind of requirements are listed below:
- Remote controls (Garage door and gate controls)
- Sensor networking
- Alarms and movement detectors
- Low rate data transmission
These devices operate from 433.075 MHz to 434.775 MHz with 25 kHz channel spacing with a maximum legal power output of 10 mW. European license-free SRD frequencies also include ISM Bands between 863-865 and 868-870 MHz (SRD860), which have a maximum legal output power of 5 mW.
In USA 902-928 MHz band and in UK 458 MHz band are the allowed radio bands, which are not allowed for usage in rest of Europe.