Studying DJI's Phantom 4 in Data Protocols and Format

Phantom 4 UAS Data Protocol and Format

Research Analysis

Miguel A. Linares

Embry-Riddle Aeronautical University

 

Introduction

         This study focuses on DJI’s Phantom 4 Aerial Photography UAV in respect to its data capture, storage, and management as well as the relevance of its sensors’ power usage on its general data strategy. The world of small UAS has taken a number of directions from drone racing for the thrill enthusiast, to aerial imagery applications in agriculture, fire-fighting, and even film-making. For all these applications, an important aspect of operations is the connectivity and transfer of data from the point of collection to the end user or operator. The type of method used can vary depending on how the UAV is used and what purpose it is serving.

 

Phantom 4 UAS Description

         The Phantom 4 is a small quadcopter UAV that precedes and improves upon the Phantom 3 Pro. This improved Phantom is equipped with more sensors expanding functionality and capability. It has two sonar radar sensors facing forward and two facing downward. There are also two ultrasonic sensors on the belly of the UAV’s main body. (Popper, 2016)  These front facing sensors send data to its intelligent flight computer which creates a 3D volumetric map of the environment and calculates a modification to the flightpath enabling the system to avoid obstacles in their 94° field of view (FOV) with detection range of up to 50 feet. (Korey, 2016) The downward facing sensors help the system hover in place and navigate mainly indoors and where a GPS connection is unobtainable. (DroneWorld, 2016) Other sensors in the system include the link connectivity sensor, which would trigger a return-to-home (RTH) mode if it senses a loss of connection with the controller. It also has a power level sensor that informs the operator of the remaining battery left via a “status LED” light bar. (Patterson, 2016) The main camera on the Phantom can take stills with 12 Megapixel quality and video recording quality of UHD (4096 x 2160) with a maximum video bitrate of 60 Mbps. The power source is a 15.2 V, 5350 mAh, LiPo 4S battery that enables approximately 28 minutes of flight time. (DJI , 2016)     

Data Format, Protocols and Storage Methods

         The Phantom 4 UAV can be used in numerous applications. When used for professional aerial photography and videography, as is the main purpose of this UAS, the data collected is generally not time critical and can wait to be downloaded from the on-board storage device once the craft lands. The UAV uses a Micro SD card with up to 64GB capacity and must have a Class 10 or UHS-1 rating. The still image data captured by the camera can be in JPEG and DNG formats, while the video capture can be MP4, MOV, and MPEG-4. (DJI , 2016) The Phantom does allow for a form of instant data transfer from the UAV while it is still in flight. However, although the camera sensor can take video with UHD and 4K quality, its download capability is limited to 1080p video and JPEGs, not 4K or higher quality imagery. (Popper, 2016)

Data Treatment Strategy Recommendations

Due to the power usage from flight and by sensor and subsystems utilization, batteries are quickly drained thus diminishing the operational endurance of the UAV. For the Phantom, I’d recommend removing onboard storage and generate an instantaneous data transfer of whatever is recorded. This will ensure the safety of the data being captured despite the fate of the UAV should an accident occur.

The way to achieve this robust connection between the UAV and the operator controller is via a large-aperture multiple quantum well modulating retroreflector in optical forms of data transfer. The emergence of free-space optical communications and the technological advancements of lasers open up a more appealing venue for data transfer due to the shorter wavelengths, which also provide lower probability of signal interception and jamming. Also, establishing the use of this connection, which enables lower power consumption and higher data transfer rates with greater bandwidth, instead of using a 2.4 GHz ISM the system will allow for the quick transfer of larger UHD quality video; a function it is currently unable perform. This larger video can be downloaded to the user’s interface but only until after the craft lands. This form of connection would also extended flight time due to greater power allocation to flight functions and to lighter payloads being carried in optical communications equipment compared to its radio frequency communications counterparts. (Gilbreath, et al., 2001) This in turn maximizes the UAV’s utility and expands its envelope of operational applications.

 

Conclusion

              There numerous ways to handle data processing and management when it comes to an unmanned system’s functionality structure, which is mainly derived with the end user’s needs and convenience in mind. In the case of DJI’s Phantom 4 UAV, the data collection revolves around high quality still images and videos. The protocols and methods used for the processing and management of this data rely largely on storage devices on-board the system limiting the user to post-flight data retrieval of the high quality imagery, and lower quality imagery downloads in-flight. An alternative method was proposed discussing the use of a simple modulator coupled with an optical retroreflector instead of RF to transfer data in near-real time, enabling larger and more secure data transfer and acquisition while consuming less energy and extending operational endurance.

References

 DJI . (2016, September 25). Phantom 4 Info. Retrieved from DJI: https://www.dji.com/phantom-4/info

DroneWorld. (2016, April 30). DJI Phantom 4 Specs. Retrieved from Drone World: http://www.drone-world.com/dji-phantom-4-specs/

Gilbertson, S. (2016, April 22). Review: DJI Phantom 4. Retrieved from Wired: https://www.wired.com/2016/04/review-dji-phantom-4/

Gilbreath, G., Rabinovich, S., Meehan, J., Vilcheck, J., Mahon, R., Burris, R., . . . Montes, M. J. (2001, July). Large-aperture multiple quantum well modulating retroreflector for free-space optical data transfer on unmanned aerial vehicles. Optical Engineering, 1348-1356.

Korey. (2016, March 3). DJI Phantom 4: What makes it different? Retrieved from My First Drone: http://myfirstdrone.com/phantom-4/dji-phantom-4-what-has-changed/

Patterson, J. (2016, July 12). DJI Phantom 4 In Depth Part 2: The Remote Controller . Retrieved from HeliGuy: https://www.heliguy.com/blog/2016/07/12/dji-phantom-4-in-depth-the-remote-controller/

Popper, B. (2016, March 1). DJI's revolutionary Phantom 4 drone can dodge obstacles and track humans. Retrieved from The Verge: http://www.theverge.com/2016/3/1/11134130/dji-phantom-4-drone-autonomous-avoidance-tracking-price-video