With around 15 kilometres of fenceline, much of it in remote areas, monitoring of the sanctuary fence has always been a challenge. Although we do regular inspections we still need to know if something happens between inspections that could compromise our pest free status. Trees fall, land slips, and rocks roll. Gates can get left open, and storm water can open any of the several water entry and exit points.

The fence was fitted with a complicated system when it was first built which monitored the status of every entry point and the state of the fence. It does this with sensors on every hatch or gate and a hotwire along the top of the hood. If anything falls on the hotwire it shorts out the electric wire, a voltage drop is detected, and a message is sent to the ranger on call, who then goes (any time and in any weather) to inspect that part of the fence for a problem.

Unfortunately, because this system was based of 3G internet, which was to be turned off at the end of 2025, we needed to upgrade. It’s reliability over the years has been a problem due to the limited cellular coverage on the more remote parts of the sanctuary. We decided to take the opportunity to adopt newer and better technology in the hope that it would be more reliable and give us better information to base our decisions on.

IOT (internet of things) is a technology that allow “things” to connect to the internet and share information. The “things” in our case would be vehicle gates, pedestrian hatches, stormwater gates, the big dam water gates, and of course the fence’s hotwire. With the guidance of TelTrac, we purchased and installed three IOT “gateways” in carefully selected places around the fenceline, where the cellular network coverage is good. These IOT gateways offer internet access to all other devices on the system, allowing them to constantly communicate their status. 

LoRaWAN is a networking protocol designed for wireless, battery operated IOT devices. It can work over long distances (10km+) if there is a good line-of-sight. The Sanctuary is around 4km wide at its widest point and shaped like a bowl, making this an ideal solution.

Once the three gateways were in place, we could begin installing sensors on all gates and hatches and water-gates. These end devices are wireless, and battery powered. They send a very small packet of data every few minutes to any gateways that can hear them. They use very little power, so batteries are expected to last 3-5 years. The data is logged and collated allowing us to see current and historical status of any device easily. 

We can also set up alarms to wake us up to emergencies. With the previous system we would get a single message saying there was a problem, with no information other than an approximate location. The ranger would have to go up and have a look. With the new system we can view the voltage for every section of fence in real time, making it easier to identify false alarms and allows us to make better decisions.

Although we have had some teething problems the newer technology is performing well. It opens many of other options for the future. IOT technology has a myriad devices available for all sorts of purposes, like weather stations, water flow sensors, accelerometers, and much more. Now that the backbone of the system is established adding extras is simple.

We would like to acknowledge the assistance of Teltrac with their expert guidance, Go Wireless NZ, New Zealand’s IOT hardware supplier, and the Swiss manufacturers of “Fencyboy” voltage monitors who were very willing to help us work through our teething problems.