This directory conrtains all of the code and documentation for the LoRa alerting link
Adafruit Feather M0 RFM9x radio modules are used for the Long Range (LoRa) radio link to send alert messages.
Arduino IDE was used to compile and download all code used for the Feather LoRa modules.
The remote sensing unit is referred to as Node-2 and the base receiving unit is referred to as Node-1. Alerts generally originate at Node-2 sensors and are transmitted back to a central Node-1 sensor (or sensors). There can be up to n Node-2 sensors deployed at any one time. Usually there will be one central Node-1 for up to n Node-2 sensors. Note: there are no reliablilty mechanisms such as retry, hARQ, ACK/NACK, etc... as you would see in TCP/IP, for example. The LoRa protocol uses forward error correction (FEC) to detect and correct some bit errors, but nothing beyond this. See the diagram below.
The remote sensor Node-2 will generate alerts originating from a detect.py script running and processing images from an IP camera. These alerts are then formatted and sent to the LoRa radio via a serial port (usually /dev/ttyACMx) on the local device. The Node-2 LoRa radio will poll its serial port for these messages and then forward them over the LoRa radio link to the Node-1 base receiver. The base reciever will then recieve these radio messages and forward them to the appropriate bus (serial, SPI, I2C, etc...) where they can be processed or evaluated.