State of the art
In this section, I will give a brief overview over existing hardware solutions.
In the last years, the market was flooded by all sorts of drones from all kinds of companies. Many of them failed because they weren’t able to deliver a good product at an affordable price. Since the release of the Phantom 1 in 2013 by a Chinese company called DJI, the market by their products. No other competitor has products that could take on DJI products when it comes to the combination of quality hardware, flight time, usability, video quality and range.
Besides DJI, there are two other companies that have reasonably good drones in their portfolio. Those are Yuneec and Autel Robotics. While Yuneek drones still lack the usability of DJI solutions, Autel has managed to come up with a drone they call Evo. That might be the only competitor the Mavic series has. “But what about the Skydio R1” you might ask. Well. I think it’s more of a technology demonstrator rather than a real consumer product. The price tag is just way too high for the video quality it delivers. It uses an Nvidia Jetson to be able to process all that information from its cameras. The jetson alone is 400-500€ is retail. If they replace the camera-based system with a 3D sensor based one (like lidar, or TOF cameras) the whole system might become competitive. Besides, it’s too noisy for 2018 and does not come with a controller. No way someone could actually get a nice cinematic shot with that one.
The radio link and flight time might be the hardest part of every drone project. There are several solutions that could be used for this project:
Traditional radio setup
- RC signal (Throttle, Yaw, Pitch, Roll) and telemetry: One or multiple 2.4GHz digital radios. One for each data channel.
- This includes solutions like the 3DR Radios for telemetry etc.
- Video downlinks: 5.8GHz analog radio.
- No interference between RC and video (robust)
- video over the less used 5.8GHz results in better video quality compared to 2.4GHz
- Low latency video (30ms – 100ms)
- Off the shelf components and no need to code new software (plug and play)
- Video gets bad when the signal is weak. A good indicator for signal quality (turn around before signal loss)
- Camera with analog video out can easily be connected (Hero4, Yi 4K etc.)
- Two different radio systems with two antennas on drone and ground station (weight, package, costs)
- Analog video: Bad quality and lower resolution compared to digital video. Much more affected by interference. Only 25mW transmitters allowed in EU, resulting in short range and easy signal loss.
- 5.8 GHz penetration
- All digital video downlink (2.4GHz or 5.8GHz)
- Plug and Play/Fly
- Low latency (~150ms). Good enough for areal photography
- Very expensive! 1000€ alone for transmitter units
- Open source
- Low latency & up to 14km of reported range (in EU expect about 1-2km without breaking the law)
- Very cheap! ~100€
- Robust and digital HD video
- Lack of proper RC implementation and documentation
- No custom android app that fulfills needs of aerial photography
- More a video downlink project than a complete solution