Build a low-power 10 km radio link
Dazzled by IoT Bluetooth Low Energy (BLE) and stuff we might overlook the license-free UHF industrial, scientific and medical (ISM) radio bands (433 MHz, 869 MHz and 916 MHz). Like BLE these bands are intended for low-power, low speed data transfers, but unlike BLE there is no standardized communication protocol, everyone can make up his or her own. Also unlike BLE, ISM can have serious range. This project shows how to use these radio bands to setup a wireless datalink with a range of 10 km (line of sight).