This was a very disconcerting and worrying experience especially as my friends 87 year old father insists on opening the door any time of the day to anyone who knocks!
As techies we discussed various options and he installed an IP camera and setup the inbuilt motion detection. The first night he got over 300 emails. So a plan B was required. I suggested a modified “Granny monitor” but using a standard external lighting PIR as the sensor.
When the PIR triggers it activates a message from an internet connected monitor using an electricimp.com device, which causes a cloud App to read a snapshot image from the IP camera and post to a database.
We use the same timeline App from the Granny Monitor but add a link to the camera snapshot. The monitor will send mobile alerts via pushover.net if there is activity during the night & early hours.
We get the odd false positives from what looks like the same cat. But we’ve caught this Arsehole one morning some time after 4am. What was he up to!
The timeline gives a quick time index to review camera video stored on a NAS device (network video recorder). And alerts tell my friend immediately if there is something going on, enabling him to act accordingly.
This is a very cheap and easy way of overcoming the obvious limitations of inbuilt IP camera motion sensors.