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title: "How Does the SmartFront Sensor Work?"
canonical: "https://farmconnect.docs.rubiconwater.com/space/SF/1931804741/How%20Does%20the%20SmartFront%20Sensor%20Work%3F"
format: markdown
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> Macro (toc)

# SmartFront Sensor Operation

![image](media://4319320b-be78-48bd-bbda-7eb514478aba)

*SmartFront sensor operation*

The SmartFront sensor is placed in an external filling well (a length of PVC pipe) embedded in the soil in an irrigation bay.

> ℹ️ **Note**
> ℹ️ 
> ℹ️ The SmartFront sensor can be removed from the external pipe (base) and installed in another base. For example, you might have external pipes installed in several bays so you can move the sensor to whichever bay you are currently irrigating. Covers are available for external pipes that are not in use.

Water is supplied from a gate at the top end of the irrigation bay. Both the gate and the SmartFront sensor are connected to data radio nodes which communicate with Rubicon FarmConnect software.

As the bay is irrigated and the water-front reaches the sensor, the water level rises rapidly in the filling well. Once the well fills, the localized effect disappears and the movement of the passing water-front controls the rise in water level. The point of inflection between the rapid rise of the filling of the well and the more gradual rise of the passing of the water-front defines the point of the surface level. Once the water level begins to level out and reach a maximum a timestamp can be calculated for the time at which the point of full depth reached the sensor. With the use of additional variables from the Rubicon Smart Meter Gateway,  BayDrive, or BladeValve Outlet and the SmartFront Sensor, the cutoff point and total volume of water applied to the bay can be calculated and displayed in FarmConnect.

# SmartFront States

The Smartfront transitions though 4 main states of operation, Sleep, Water Detect, Ground Detect, and Max Level Detect. Each state is explained in detail below.

## Sleep

The **Sleep** state is the state in which the sensor spends most of its life. Periodic bursts keep FarmConnect aware of the device as well as providing details of the default state of the pipe (rain levels, post irrigation drainage of or ingress inside the chamber). Due to the device being low powered in nature the periodic burst also awakens the radio for reception of downlink transmissions which are critical to alerting the device of a starting irrigation.

## **Water Detect**

The **Water Detect** state is activated when the current time is greater than the *Open* time of a bay related to the Irrigation program sent down in advance to the SmartFront Sensor from the sync’d program. The poll period increases and waits for the water in the pipe to reach the bottom of the Internal pipe (0mm reference point) before transitioning to the **Ground Detect** state.

## Ground Detect

During this state the SmartFront sensor tracks the fill rate of the pipe between fast periodic polls to determine the point at which the pipe becomes full, as there is more volume to fill around the outside of the pipe than the inside of the pipe the rate at which the pipe fills above ground level decreases, and the device can calculate the average field height.

## Max Level Detect

After detecting the ground level the sensor transitions into the **Max Level Detect** state where it polls less frequently and awaits the water height to stabilise, this level can then be used to calculate the height of water above the ground level. This information can be fed back to FarmConnect for use with other information such as bay width and length to work out the total volume of water above and below the field based on how long the gate has been open as well as how much remaining volume is left to dynamically close a gate resulting in minimal water runoff.

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