Why did EnOcean opt for the 868 MHz frequency band and not for the 433 MHz band that is also commonly used in telemetry systems?
EnOcean technology works in a wireless channel at 868.3 MHz with a bandwidth of 240 kHz that has been released in Europe exclusively for short data transmission. All users of the wireless channel may only operate with 1% duty cycle, meaning maximally 0.6 seconds transmission in one minute. In contrast to the 433 MHz telemetry band, here the transmitting power is also limited for all users to 10 mW. At 868.3 MHz there is neither walkie-talkie operation nor the often very strong interference from medical radiotherapy apparatus. Nor are there radio amateurs, who can cause a lot of interference to secure wireless transmission.
