[Last updated 5th Feb 2023]
About The Possum TV Live Server
History
In 2005 I put up two nest boxes for the benefit of local possums. I was keen to know if possums were using them, but this required either opening the lid of the box during the day, which required the use of a ladder and would have disturbed any possum inside, or waiting outside the box at sunset - potentially for hours - to see if a possum emerged.
An obvious solution was to put cameras in the nestboxes.
At the time, Melbourne Wildlife Sanctuary had a number of live streaming webcams, one of which was from a sugar glider box. (Unfortunately, not only does this site no longer exist, but even the domain is gone, however there is a copy on the Wayback Machine if you're interested.) I thought this was great and wanted to have something similar, although at that time I was happy enough to just be able to check the boxes on a TV, with perhaps the option to record footage on a VCR.
Surveillance cameras were much less of a thing in that dim distant era, but I found a camera that did what I wanted. It was the "Swann Day-and-Night Camera" pictured to the right. This was very simple to use and not too expensive. It was small enough to fit inside a possum box, it had an infra-red illuminator and it had a very long cable (for which you could buy extension leads). It was powered by a plug-pack and it provided analogue audio and video outputs which you could connect into a VCR.
This was good as far as it went and it even allowed me to record sound (which is something I'm currently unable to do) but it had some drawbacks. The use of a VCR was cumbersome and unless you manually start recording at the right time you could miss interesting things that were happening. Keeping a collection of footage on VHS tape was also going to be expensive and there were no time and date stamps on the recordings which meant everything had to be manually labelled. Security camera systems could be purchased that at least partially solved these problems, but these were expensive and had other limitations.
Then I found an awesome piece of open-source software called Motion which gave me a way forward. This was originally developed by Kenneth Lavrsen but has since changed hands. Motion takes input from video cameras via a video input card (or other source) and can record and stream the video in a variety of ways. You can add time-stamps and other information to the videos and, crucially, it did motion detection - it could be made to record automatically when something was happening in a possum box.
There was other software around at the time which did similar things, but Motion ticked more of the boxes. Especially important was that it ran on Linux rather than Windows. I wanted to set up a web server if possible and I felt that running Windows was just asking to get hacked.
By December 2008 I had assembled a Linux computer with a video input card hooked up to cameras in two boxes. There were all sorts of teething problems but by February of 2009 the server was fully running and on the web. Although the system has subsequently been modified and added to, and the server computer, video input cards and box cameras have all be replaced at least once, the current system is fundamentally the same as the original system I put together at that time.
Current Setup
This is a brief overview of the system. I won't at this stage put more detail on this site. I have tried that before and I always forget to update it and it gets out of date, which makes it misleading to viewers and embarrassing to me. Instead, if you want more technical details, please contact me directly ().
The server computer was assembled from parts rather than purchased off the shelf, but is a fairly standard (and by current standards somewhat under-powered) desktop computer. The CPU is an i3. I have tried to optimise it for power-saving because it runs 24/7.
The computer runs LFS (Linux From Scratch), which means there isn't a whole lot of extraneous software to get in the way and cause trouble. I have kept away from anything which sounds dubious or has a history of problems; such as systemd and PHP respectively, and I've locked down everything else as much as I can.
A single 8-input PCI analogue video input card has been fitted to the server.
Each of the 8 possum boxes has a camera in it. A variety of different cameras are now in use, with the latest ones being custom made from cheap eBay drone cameras. The original Swann cameras haven't been available for something like 10 years now.
All of the cameras use infra-red LED illuminators because the boxes are deliberately made as dark as possible inside and even in daytime there is not enough natural illumination. The IR illuminators are home-made and operate at 940 nm. This wavelength is less efficient for use with cameras than the more commonly used 840 nm, but it is invisible to the naked eye, whereas 840 nm has a dim red glow.
All of the cameras have an analogue video output which is cabled back to the server via coaxial cable. There is no wireless involved.
In addition to the camera, each box has a temperature sensor in it. I have used AD592 temperature sensors. These are a two-wire analogue current loop sensors which are wired back to an ADAM-6017 Modbus/TCP interface. This is in turn scanned by software on the server, which logs it to database and sends it to Motion where is displayed under the time-stamp on the video.
All cabling is enclosed in electrical conduit. This is was a giant pain to install throughout the garden but was necessary to protect the cabling.