File: 01sherman.lt1.doc
[Headline: Reliving the ride]
Although you might think otherwise if you’ve ever typed “FPV” into YouTube—a query which yields about 1.7 million results—not every First-Person View (FPV) flight conducted during the past several years has been recorded on video, much less uploaded to the Internet.
Although video capture is a common feature among FPV systems, it is not a requirement—unless you want to relive or share your adventure with someone else. If you choose to record your FPV flying, you still need to make some important decisions. These will determine the quality of the video and what you will see when you play it back, and could even affect your aircraft’s safety.
I’m going to discuss five basic options for configuring your FPV system, plus a few variations. There are myriad possible combinations and permutations among these fundamental approaches, and countless alternatives as well. Use this information to get started then use your own creativity to tailor a system that meets your needs.
Coming to Terms
Before considering the merits of different configurations, let’s define some terms.
• Sports camera: Any camera (such as the GoPro Hero series or the Mobius) that can record high-definition video, is powered by an internal battery, and is capable of passing live video through to your FPV system.
• Board camera: A small, lightweight video camera that resembles a lens mounted on a circuit board. All it does is output video, typically in standard definition. It has no independent power supply or recording capability.
• Digital video recorder (DVR): An electronic device that is capable of capturing a stream of standard-definition video from an external source, such as a board camera.
• On-screen display (OSD): A system that superimposes aircraft telemetry through your FPV video signal. The most basic OSD configurations simply provide your current battery voltage, while more sophisticated systems resemble the heads-up display on a modern jet fighter, with ladders indicating altitude, airspeed, distance and direction to home, and a wealth of other information.
Blind-Eye Sports Camera
Just as not every FPV flight ever made has been recorded, some flights made without FPV systems have been recorded. This has become more common with the introduction of small, rugged, lightweight sports cameras, but people have been putting cameras on hobby-built flying machines for decades.
As a boy, I flew Estes model rockets with my father, and the pride of my fleet had a still camera built into the nosecone. The ejection charge would (sometimes) trigger the camera, resulting in a single, grainy, random photograph being taken at the rocket’s apogee.
You have much more control with an RC aircraft than you do with a rocket, but this is the fundamental premise behind a “blind-eye” camera configuration. Mount the camera, start it recording, go flying, and then see what you get when your machine is back on the ground.
It’s no substitute for the immersive experience of flying FPV, but it definitely has its charms. When we were getting our start as the Roswell Flight Test Crew, we flew with sports cameras long before we got an FPV system online—and returning home after flying was nearly as exciting as heading out to go flying in the first place.
To my wife’s consternation, we would sit around for hours afterward, watching and re-watching every frame of video downloaded from the camera, thrilled by the aerial perspective of where we had just been.
Sports Camera
This was the first configuration that we utilized. It yields clean, high-definition video and because you’re watching the output directly from your sports camera, you have the ability to perfectly frame your shots. What you see is what you get.
There are some disadvantages. If its internal battery runs dead, you’ve lost your only source of video from the aircraft. Having your goggles fill with the message “Memory Card Full” is a recipe for profound frustration.
Furthermore, if your sports camera is mounted on a brushless gimbal to capture smooth, steady video, you will lose an important cue that many FPV pilots rely on to fly safely: using the angle of the camera to maintain awareness of the aircraft’s pitch, roll, and yaw.
Board Camera
Using a board camera as your FPV video source eliminates the potential for a sports camera failure to bring your vicarious aerial expedition to an abrupt and panic-inducing conclusion. Of course, board cameras can also fail, but they are less likely to do so than a sports camera. One drawback is that you will not have a recording of your flight.
You can overcome this by adding a DVR to your FPV system. You can install the DVR on the ground, splitting off a separate video feed from your receiver with a simple Y cable, in which case you will not only capture the video of the flight itself, but also your OSD output and any interference you encounter.
Alternatively, you can mount the DVR onboard your aircraft, either upstream or downstream from your OSD, depending on whether or not you want clean video or you also want to capture aircraft telemetry.
The downside to an onboard DVR is that it can introduce latency into your video signal, and a half-second delay can be the difference between a dramatic low pass over a towering oak tree and having to cajole one of your friends into climbing said oak tree to retrieve your aircraft. Furthermore, DVRs can have bad days, just like sports cameras, knocking your FPV system offline altogether.
You can eliminate latency and the risk of DVR failure by putting a video splitter onboard your aircraft, creating two separate streams of FPV video. One stream goes straight to your video transmitter and the other one to your DVR.
Board Camera with a Blind-Eye Sports Camera
This configuration gives you two independent video systems onboard: one to provide you with your live FPV feed and the other to capture high-definition video. This was among the first types of systems used by early FPV pilots. It is robust, reliable, and can deliver some great results, especially when using a brushless gimbal to stabilize your sports camera.
The only downside is that you can’t actually see the video that your sports camera is capturing while you’re in the air. It could even quit working, so you will only know for sure that you have the shot you want after your machine is back on the ground and you review the footage.
Board Camera and Sports Camera with Video Switch
We typically use this configuration for the Roswell Flight Test Crew. We have a board camera, a sports camera, and sometimes a third video source such as a forward-looking infrared thermal-imaging camera, all connected to the FPV system via a video switch onboard the aircraft.
With a three-position toggle on the radio, we can alternate between cameras while the aircraft is in the air. This allows us to see what the sports camera is recording, and provides a backup if it stops working midflight. It also provides immediate access to cameras with special capabilities, should circumstances change while we’re flying.
If the sun goes down, it’s not a problem. Switch to a low-light camera. Is the aircraft enveloped in a cloud of smoke? Select the feed from the thermal imaging camera.
The risk with this configuration is that the video switch itself becomes a single point of failure—if it stops working, everything is lost. That’s not happened to us, but it is a possibility.
Whatever configuration you choose for your FPV system, always keep safety and reliability foremost in your mind. Remember that all mechanical and electronic systems will fail at some point, so anticipate that happening and always fly at a time and place and in a manner that minimizes the risk to yourself, other manned and unmanned aircraft in the vicinity, and vulnerable persons and property on the ground.[dingbat]
