You may well ask 'What's wrong with an ordinary security system?' ….. Well, the problems I had are listed below:
- Very long cables were required due to distance of gateway from the house. Other cameras use WIFI, but this is not strong enough to cope with the distances involved.
- Although the system had an alarm output, there were a lot of false positives which were vey annoying. The system would sound alarms for cars and, worse, shadows of lorries driving past the gate.
- There's no ability to sense how close people were to the camera or whereabouts they were in the frame.
My eventual solution satisfied all my criteria - the system eradicates nearly all false positives and transmits 'intelligent' data with a range of about 15 km which means that I could monitor the system whilst walking the dog on the local beach!
How does it work? ……. There is a transmitter unit, shown above, powered by a Raspberry Pi and a receiver unit with an Arduino MKRWAN 1300. The Modividius USB stick helps speed up processing on the Raspberry Pi to such a degree that it makes it 'useful' and 'accurate' and a 'neural network' is used to 'infer' the position of a person in the frame of a camera. Python scripts are used to grab the data, process it and send relatively short lines of data over the radio frequency airwaves using the long range LoRa protocol.
This is the Arduino receiver below: