Cellphones play key role in most telemetry systems

So far in this series of articles on telemetry, I’ve written about how wireless signals work, how telemetry works and what it can do.

What is missing is how to actually set it up to operate.

Most of the time it sounds easier than it actually is. The good news is that precision ag companies have integrated systems that do most of the setup for you.

Telemetry refers to wireless transfer of data, though precision agriculture has focused on the transfer of field data to and between the field, office and vehicles.

Walkie talkies and CB radios are wireless devices. They are set up by merely tuning each of the transmitting and receiving devices to the same channel or radio frequency.

Another example is the data transfer between RTK mobile base stations and field rovers.

An RTK base station requires a radio that is configured as a transmitter, as well as other settings such as a specific frequency, type of signal, an ID code and possibly the baud rate, which is the rate at which electrical signals are transferred. Most of the time, manuals provide recommended settings.

The rover GPS must also have a radio but be configured as a receiver with all the same settings. If the settings are different, the transmitter and receiver don’t “talk” and no data is transferred. Most mobile RTK bases work on a similar basis: a transmitter for output of data and a receiver for input of data using radio signals.

The growth of telematics in recent years is largely due to the increased use of cellular signals, which is where telematics gets more complicated.

Cellular signals are used by cellphones and include a nationwide network. The modem is the basic part of a cellphone, which transfers voice and data to a wireless signal. A gateway modem is a device that connects the cellular signal directly to the internet, or possibly other networks.

I have a dumb phone, which is to say a phone that provides only voice service and not data service. I have an iPad that provides data service but not voice service.

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Most of you have a smartphone that receives both voice and data service.

As a result, you contract with a carrier for a voice plan and a data plan that is paid monthly. In precision agriculture, most companies rely on a modem and cellular data service to transfer data between devices and thus require a monthly data plan fee.

So how does a precision agriculture telemetry system work with cellular data?

As an example, I’ll use the transfer of sensor data from the field to a user’s smartphone or tablet.

A field sensor may be an ET (evapotranspiration) sensor in an orchard, a temperature gauge in a grain bin or a fill level sensor in a storage tank. This would be data that can be sent to the office or smartphone on a regular interval instead of a person travelling to every location to collect the data on a USB stick or manual transfer.

First, there needs to be a transmitter at each sensor.

If there is only one sensor, it might be directly connected to a modem, which moves the data into a cellular signal.

If there are multiple sensors, such as a set of ET sensors, then there is likely something known as a “sink” with a gateway modem. All of the ET sensors are using a radio frequency to transmit data to the sink, which collects them. The gateway modem them sends them out as a cellular signal.

So where is the data being sent?

In most cases it is being sent to the Internet of Things (IoT).

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If you haven’t heard of the IoT, it’s the same old internet with which you are familiar, but IoT is the part that connects all those other “things,” such as sensors in precision agriculture.

Data can go a lot of places once it’s in the internet. Most likely it goes to a computer server to be stored and becomes part of a database.

From there it may be displayed on a website, which people can go to and look at the sensor information.

It could be made available directly to a cellphone in the form of a text message.

Or it might just be available to a few people, who can access the computer server for their own use.

Each system will be different, but if you are a user of a wireless network, you will likely have a user name and password that provides you access to all the data in one or more ways.

Another major use of telemetry is transferring data between vehicles or implements in the field.

Each vehicle will share guidance lines, harvest data or coverage maps to identify what the other machines have done. Allowing a fleet of vehicles or implements to communicate in this way requires a modem in each vehicle and a data plan to carry the data through a cellular network.

The home office would also have the same modem, which allows all data out in the field to be shared at the office. This is real time as the data is being collected, viewed and stored.

Terry A. Brase is an educational consultant, former precision agriculture educator and author. BrASE LLC. Contact him at precision.happens@producer.com

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