I currently have 9 irrometer sensors to measure the soil tension (kPa) in a sugar cane farm (see image). I am also taking these readings manually using a single arduino reader. So, each morning depending on the reading we decide if it’s time to irrigate the field.
I am new to the LoraWan tech, but I think this could be the best approach to take automatic readings, and we could display this data in a nice dashboard.
The gateway will be placed were the marker is in the map. That is were we have the house and the Internet access.
About the installation of the gateway I have some questions:
Sugar Cane can get as high as 5 meters. The house isn’t that tall, so we are planing to install the gateway in a pole. Our farthest sensor is around 1.5km away from the house.
How high do we have to install the gateway to get to a 1.5km away node?
Is the 5.8dBi antenna enough? Or should I get the 8dBi. If I get the 8 dBi antenna, the recommendation is to install it with a feeder line cable which is 1.5m long. But I read that the longer the cable the higher the loss in dBi.
Nodes Arduino MKR 1310
The nodes will be placed in a IP67 case and will be powered using a battery. The idea is that the battery has to last for 13-15 months, so we only have to charge it once per harvest. These nodes will be placed in a pole, and the idea is to install the nodes at around 6 meters tall.
Do I need and external antenna for each node? or can I use the antenna included with the arduino 1310 and install it inside de plastic case?
Do I need to make these poles higher or is 6m enough?
Lora Server
I want to take readings every 15 minutes, and save them in to my database so I can make a dashboard with the data.
Should I use TTN ? Or can the gateway send the data directly to a custom endpoint so I can consume the data as json in my own server?
Especially if you elevate the gateway antenna about the house, it’s probably unecessary to elevate the node, as the cane stalks probably aren’t dense and wet enough to constitute a full obstacle.
Bu the easiest answer is to go out there with one node with integral antenna and try it.
Probably you want to try one node before you buy all of them anyway. In theory you could do a node-to-node test for ranging before investing in a gateway.
Note that true low power design is an art with near countless things which can go wrong; you’ll want to carefully validate your setup, or be prepared for the possibility that something that was supposed to last over a year dies in the initial attempt inside a month due to an overlooked leakage path.
Just for curiosity. Could you share the kind of irrometer that you are using? Does it provide a direct analog ( or digital ) signal representing the pressure? What are its power requirements: voltage, current.
We are using the WATERMARK Soil Moisture Sensors model 200ss. We use an Arduino Uno, and using a digital pin (5v), and an analog pin you can read the resistance of the the sensor. Which can then be converted to kPa using the formulas provided by irrometer. They also provide an example of making your own Soil Moisture reader here.
Hi @silverio,
I have experienced after a while as an agricultural engineer at a dairy farm, we look after corn for food.
Some of my tips are as follows:
Antenna gateway as high as possible, but preferably above 5m, if not possible, make sure face to face. A parked car can also cause you to lose data.
Please balance the length of the sensor wire and antenna. Sugarcane stalks or whatever is an obstacle to significantly reducing the signal. I usually keep the sensor wire longer than 2m and the antenna wire 2m. We accept that when the sugar cane grows, it will obscure face-to-face. You can experiment with them to see what the longest possible sensor wire is.
I had problems when the plants were young I achieved face-to-face, but as they grew they obscured the solar panels and interfered with the signal resulting in the nodes not being able to function as they should. The height of the antenna will be limited by the irrigation devices. In the worst case, you can use a node to set up a signal repeater.
