Sunday, August 17, 2014

Got a new camera!

We got a new camera last week! Here's a video from the first week of ownership.



It's a DJI Phantom 2 Vision + (Plus).

This is my first "non-toy" radio control device. I'm amazed at how much technology has changed model aircraft since I was a kid.

The Phantom, or any quadcopter for that matter, would be very difficult to fly without the tiny gyroscope and flight control computer in it. Fortunately, the craft is amazingly easy to fly. It is easy to get over-confident with it, though. Even with all the fancy technology, crashing it is still a real possibility.

The Phantom also has a compass and a GPS receiver built into it. Both of those allow the aircraft to come to a fairly stable hover when both control sticks on the transmitter are released, provided it's not too windy. The GPS, if set correctly before flight, will allow the quad to fly itself back to the launch point if the transmitter signal is lost.

The flight computer also tracks how much energy is left in the battery and calculates how long it would take it to get back home before the battery is depleted. Once the battery reaches a certain discharge point, it will return to home automatically.

I like how smooth the video comes out. Watching it fly in a wind would make you think that the video would be herky-jerky, as the aircraft body often oscillates quite a bit. Thanks to the brushless 3-axis gimbal that DJI camera is mounted on, the video is quite smooth.

The only slightly disappointing part is how the camera tilt function works. The motion is very smooth, but starting and stopping the tilt is very sudden and mechanical looking. This is very obvious when watching the video on a computer.

The Phantom also has a video and telemetry downlink. The transmitter comes with a clamp to hold an iOS or Android smartphone. The free DJI Vision app displays the camera feed on the smartphone screen, enables you to change camera settings while the machine is flying, tilt the camera, take stills, and start or stop the video. Unlike a GoPro, the camera can't take still pictures while recording video.

The downlink video is pretty good even at 15 frames per second. I haven't tried any of the higher frame rates yet. The weakest part of the system is my iPhone 4s. Even when I turn the screen brightness up to 100%, the screen still gets washed out in the sun. Compounding the problem is the reflective screen of the iPhone. I'm currently looking for some way to shade the screen.

The telemetry sent back from the Phantom is interesting, but I have doubts about its accuracy. I have yet to get an accurate altitude even when the quad is on the ground. In one instance, the altitude meter indicated –20 ft, or underground.

Other things on the screen are the number of photos that can fit on the MicroSD card at the current time, how many GPS satellites the Phantom has contact with, Phantom battery level, WiFi range extender battery level, and relative WiFi signal strength.

The video and telemetry data are transmitted over a 2.4 GHz WiFi signal. The transmitter came with a WiFi range extender attached to it. Being on 2.4 GHz, though, means that the signal can be degraded by getting too close to a home WiFi base station. I have experienced the video feed freezing up on me a couple times so far, perhaps due to flying within range my neighbor's base station.

 Off to practice some more!