The communication protocol between the sensors and the Hub is called SmartLink, which is a proprietary protocol designed by Airthings to ensure long-range communication with a low power consumption footprint. We currently have no plans of making this protocol publicly available.
Frequency band depending on the geographic location (due to local regulatory bodies such as FCC and ETSI), based on IEEE 802.15.4g with FHSS, 50kbps.
Europe/ETSI: 868 - 870
North America: 902-928
Singapore + Hong Kong + Malaysia + Thailand: 920-923
Oceania + Japan: 923-928
Australia + New Zealand: 923-928
Indoor: 3 thick concrete walls/floors or 10 drywalls in an office building (>1km Line of Sight).
Place a Hub within 40m of a sensor. The signal depends also on the number of walls and the layout of the room. The more walls between the Hub and a sensor, the closer you will need to place a Hub.
Robust link down to received signal strength indication (RSSI) of -85 dBm
Wireless communication is a delicate and complex physical topic that may seem straightforward in a theoretical world. In the real world, not all aspects of a wireless link can be controlled even though theoretical models might suggest so. This includes topics such as multi-path fading but also general interference and noise. We have designed a robust and solid protocol as resilient as possible, although there are still some geographical locations and building architectures still prone to challenges such as (but not limited to); old industrial constructions or deep underground areas. These types of locations should be evaluated first.