Receiving wireless sensors operating in the unlicensed ISM band has been made almost universal with rtl_433 and RTL-SDRs. However, recently rtl_433 has been ported over for use on ESP32 microcontrollers that are combined with CC1101 or SC127X transceiver chips.
PCB boards that combine these two chips can be found cheaply on Aliexpress as LoRa boards, under the name “LILYGO LoRa 32”. If you are unaware, ESP32 chips cheaply combine a WiFi and Bluetooth modem with a microcontroller that is capable of hosting a webserver. CC1101 and SC127X are low cost low power hardware transceiver chips made for IOT devices. We’ve posted about LILYGO boards in the past as they’ve been used with interesting projects such as Meshtastic, and for weather balloon tracking.
This project could be useful for home automation as a module has been made available for openMQTTGateway. Instead of dedicating a more powerful Raspberry Pi and RTL-SDR, you can now dedicate a much cheaper and much lower power device to the task.