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Team Drone Stars: Sean McKee, Arwa Mohammed, Obaid Alqahtani, Adam Gossett, Adam Jones
Sponsored by the Center for Environmental Technology, CU Boulder

The Problem

Fresh water is perhaps one of the most valuable resources in the world. The amount of available fresh water is a fixed amount, but demand for that water continues to grow. Drought prediction and water management are increasingly important in the modern world.

Project Drought is an ongoing collaborative effort headed by CU’s Center for Environmental Technology and the Research and Engineering Center for Unmanned Vehicles. One of the goals of Project Drought is to develop a small Unmanned Aircraft System (sUAS) in collaboration with Black Swift Technologies that is capable of taking soil moisture measurements at 5 - 20cm depth at a 15 meter resolution.

Previous revisions of the Soil Moisture Detection Drone (SMDD) have had some success using Lobe Difference Correlating Radiometry. These previous revisions have used an on board analog-correlator and stored the data for post-flight processing. There are two large obstacles with this approach:

1. The external digital circuitry such as the large hard drive and the associated cabling produce a lot of noise that obscures the extremely sensitive signals of interest.
2. All of the data is stored raw without processing which requires a large amount of on board data storage.

The Solution

This revision of the SMDD is another step in moving towards full digital correlation and on board real time processing. The I/O part of the Soil Moisture Drone is on a single, custom designed PCB carrier board. Incoming signals are digitized as soon as possible. These signals are then sent to the FPGA via the micro headers and then the processor and programmable logic do on the fly processing and reduce the amount of data that needs to be stored.

End Users

The initial users of the SMDD will be the members of Project Drought as they continue to collect soil moisture data for analysis. There is also a potential for the SMDD to be marketed to agricultural research centers, agricultural consultants, and farms employing precision agricultural techniques.

Key Features

• All hardware is connected directly to the board or interfaced with microheaders, eliminating excess cabling and interface hardware, both of which are large sources of noise.
• On board power management means the whole digital end of the SMDD can operate on an isolated power source. This eliminates potential for interference via power spikes from motors or analog oscillators.
• FPGA allows for on the fly processing, reducing the amount of data that needs to be stored.
• On board SD Card means there is no need for an external hard drive to store the data. Hard drives are notoriously noisy in the RF spectrum.