7 Key Factors to Consider with Wireless Field Monitoring Systems

7 Key Factors to Consider with Wireless Field Monitoring Systems

This white paper provides an overview of the wireless field monitoring alternatives available today, and is intended to help you determine the best system for your needs, based on your unique application requirements. Highlighted in the following pages are six important factors to consider when selecting and deploying the most optimal solution. These factors are:
1. Ease of deployment
2. Wireless sensor coverage
3. Actionable information
4. Alarm notifications
5. Maintaining complete historical data
6. Total cost of ownership
7. Scalability and Future Proofing

1. Ease of Deployment

When evaluating different wireless field monitoring systems, you should be mindful of the deployment process required with each option and prioritize solutions that minimize complexity. With some systems, the wireless nodes need to be programmed as part of the setup, requiring you to dedicate time to understand this process or seek outside help. Due to the deployment complexity of some systems, certain suppliers also offer installation services as a separate cost. To avoid difficulties with deployment, you can instead opt for a solution that provides simple, push-button configuration for adding sensors. Moreover, nodes that come with sensors already connected are much faster to deploy as compared to those that require programming for each sensor connection. Wireless sensor networks that have an intuitive, user-friendly interface for mobile devices or laptops also make for a simpler configuration.

For deploying wireless field monitoring systems, you should also consider:
• Solar panel configuration. Most wireless nodes use solar panels with rechargeable batteries. Sensor nodes that have built-in solar panels can be deployed faster than those that require you to connect and mount external panels.
• Transmitter size. Transmitters that are small can easily mount on a PVC pipe or a fence post. Larger transmitters may need a tripod, which can be a problem for deploying in some crops. In evaluating the transmitter size, consider the machinery that is used to manage crops. The smaller the transmitter, the easier it is to mount, so as to not interfere with operations.
• Mounting flexibility. You should also consider how easily the transmitters can be mounted. A transmitter that can be attached with zip ties or a couple of screws will save time compared to those that require bolts or U-bolts.

Look for wireless sensors that are small and that have integrated solar panels for easy deployment

2. Wireless sensor coverage

In evaluating different options, carefully consider the type of wireless system in order to better evaluate whether the wireless sensors will have the range to cover all the sites you need monitored, while providing the reliability to ensure you can view conditions and receive notifications during critical times.

Wireless frequency used. As compared to options that use 2.4 GHz, wireless sensors that use transmissions in the 900 MHz range for communication are better suited for transmitting through and around vegetation. This is especially important as the crops grow, and more vegetation is present to interfere with communications. Rain can also interfere with wireless communications (water attenuates wireless signal strength). Wireless signals in the 900 MHz range will be less attenuated than signals in the 2.4 GHz range.

Star vs. mesh network. Both of these networks use a web-enabled, central receiver to consolidate data from the wireless nodes. With a star network, all of the wireless nodes communicate directly to the central receiver. As such, the maximum range that can be monitored in any direction from a station is limited by the wireless range of that sensor. Mesh networks, on the other hand, have nodes that can relay signals from other nodes. These networks allow multiple “hops” (a hop counts as one transmission step between two nodes, or from a node to a central receiver), so that you can obtain a wider coverage range. Also, repeater nodes can be added as needed for longer distances.

Additionally, mesh networks offer a more robust wireless network by allowing signals—and the transmission of data—to take alternate paths back to the central station in the event that a sensor goes offline, thereby providing redundancy and greater reliability. When looking at mesh networks, one of the specifications to check is the number of hops back to the receiver that they support, as this will determine the maximum coverage range.

Mesh networks allow “hops” to obtain a wider coverage area.

3. Actionable Information

More than receiving raw data, you need a solution that helps you make the best decisions. With this in mind, you should seek out a wireless field monitoring system that allows you to better visualize conditions across your monitoring area and provides actionable information that’s clearly communicated in real time, through either:

• A map view, which shows current sensor readings on a map, or

• A dashboard view, which offers a customized look at the most critical parameters and can include visual gauges that show current values or graphs for viewing trends or recent historical data

A well-designed dashboard, for example, would enable you to view your operation and understand where attention is needed, such as spots that are abnormally cold or dry. When considering systems, you should look for ones with dashboards that offer:

• Compatibility with the platforms you use in the office and the fields, including laptops, desktops, tablets, or smartphones

• Ability to integrate data from multiple stations and networks into views that clearly show the most critical information needed to make decisions

For agricultural use, you should also search for software that can leverage climate data to inform you when actions need to be taken, such as irrigating your crops or applying pesticides. Common software tools include:

• Evapotranspiration (ET): to determine crop water use to help decide when irrigation is needed; ET is also an important parameter for hydrological modeling and applications such as water resource management

• Growing degree days: to determine when plants or pests are reaching critical growth or development stages

• Crop disease models: to calculate the risk of disease or pest emergence and the optimal time to apply pesticides or fungicides

If the vendor’s software doesn’t have the ability to process data to the form that is required, you may be able to feed your sensor data into software available online to derive decision-making parameters. Examples include:

*Integrated pest management software from the Network for Environment and Weather Applications

**The DEGDAY Excel application from the University of California, Davis for calculating degree days

Researchers may want to visualize and work with data in a preferred platform. Consider the software’s ability to easily export data in different file types. It may also be helpful if the software can automatically export data for use with third-party statistical tools.

Systems with a dashboard enable instant visualization of your data.

4. Alarm Notifications

Consider a solution that can detect alarm conditions based on sensor readings or calculated parameters and provide notifications when conditions reach critical levels.

You should also think about where the alarm conditions are detected, because this influences the alarm response time. Systems that use web-based alarm detection require data to be uploaded to a website before readings are checked against alarm limits, which means the alarm response could take as long as the upload rate plus the maximum internet-latency time. A better option might be a system that checks alarm conditions from within the station and connects to the internet as soon as an out-of-limit condition is detected, instead of waiting for the next scheduled connection. As soon as the station connects, an alarm notification is sent automatically, typically as a text message or email.

Another aspect to consider is whether a system can also be set up to trigger a relay. For example, a system that sends a frost alarm when a low temperature threshold is reached would at the same time close a relay that turns on an irrigation system, spraying the crops to provide protection from freezing.

One further element to seek out with respect to alarm notifications is whether the system provides “hysteresis,” such that an alarm can be triggered on one level and be cleared at another level so that you don’t receive multiple alarms when  turning conditions are near the alarm threshold. By allowing a system to be more tolerant of conditions that are hovering near the alarm threshold, hysteresis prevents alarms—and systems—from turning on and off repeatedly in a short amount of time

Look for a system that can provide real-time alarm notifications of critical conditions

5. Maintaining Complete Historical Data

If you are currently using or are exploring the use of historical data as part of your research project or growing operation, it is important to look for a system that ensures complete historical records by retaining data in the wireless nodes until upload is confirmed. In the event of a break in the wireless transmission, such a feature prevents data from being lost. Ideally the system will automatically upload the data from the nodes when wireless communication is restored, or worst case, the data can be offloaded directly from the nodes with a USB cable.

For crop management, the availability of reliable historical data allows growers to analyze field climate conditions over time and identify longer-term trends and conditions that may be affecting their yields, enabling for more strategic planning. For example, long-term temperature data could help vineyard managers identify areas in their fields that are historically colder and where more tolerant grapes should be planted. Historical data can also demonstrate that a grower only sprayed when conditions were safe, minimizing the chance that pesticide could have drifted into a neighboring field.

Historical data storage enables more informed analysis and planning

6. Total Cost of Ownership

Be sure to consider all costs that might accrue over the lifetime of each wireless monitoring system you evaluate. These costs can include the purchase of a gateway station, wireless sensor nodes, data service plans, and mounting stands or poles.

You should also consider costs associated with installation of the system, as well as annual maintenance. Complex systems are more expensive to install, and paying a little more upfront for a reliable, low-maintenance system can save you money in the long run. Importantly, if a system fails at a critical time, the potential cost of  research data loss or crop damage/loss could be severe.

Whether the wireless system operates a star or mesh network can also have total cost of ownership implications. This can be especially true if you plan to expand in the future. For example, where a star network may force you to purchase a new station due to range limitations, a mesh network might allow you to simply add more nodes to expand coverage.

Be sure to consider all costs that might accrue over the lifetime of each wireless monitoring system you evaluate. These costs can include the purchase of a gateway station, wireless sensor nodes, data service plans, and mounting stands or poles.

7. Scalability and Future Proofing

When selecting a field monitoring system, you will want to consider possible future needs. This may come in the form of monitoring additional microclimates, monitoring nonenvironmental factors such as energy usage or equipment runtime, or the desire to integrate new sensor types and technologies.

Consider the type of input options the system provides. For many applications, the manufacturer’s compliment of environmental sensors will cover all your needs. However, in other applications you may want to integrate sensors not available through the weather station manufacturer. In these cases, look for options that can integrate third-party sensors with different input types, such as analog or pulse inputs.

Conclusion

Your investment in a wireless field monitoring system can directly affect the quality of your research, or the profitability of your growing operation. Selecting the right system for your application is an important decision, so you’ll also want to look for a provider that not only has qualified application specialists to help guide you through the process, but also offers long-term customer support.

Interested to know how we can help you in installing a Wireless Field Monitoring System? Feel free to contact us!