Wireless Video for Remote Control Aircraft

By Don R. Giandomenico N6YIY
 
Photo of Cub with camera mounted to wing.
Video taken at the MARKS Club flying field.
 
When it comes to flying R/C Aircraft, nothing can be more exciting than getting real time video of your flight. With a live video link you are able to “board your aircraft“ and see what you cant from behind your transmitter. For me it all started with a still camera installed in an old trainer plane I had. The still photos I took looked neat but it was hard to aim the camera from the ground. I wanted a system I could see from the ground and maybe even pilot my airplane like a military drone aircraft.

I started researching what systems were available and the range they offered. There were some projects that utilize a consumer grade security camera made by X-10 (X10.com ) that transmits on 2.4 gigahertz. This system did not appeal to me because the range was limited to 100 yards or so and the frequency used does not work well around obstructions. Although this was a limited range system, It is a good match for helicopter use because helicopters can fly a tighter flight pattern unlike an airplane. This type of system does not need an Amateur Radio License to operate (as some units require a HAM operators license to operate) and can be put together for $150 - $200. There were some other systems that were complete unit including video camera and transmitter ($120) that transmits a color image on UHF frequencies but the output power was low and promised only 300 ft range max. (Available at plantraco.com) I wanted a system that would easily transmit a picture a quarter to half mile away. I searched further and found a web site wirelessvideocameras.com that also had pre-packaged units for R/C use. They have a few units that did not require a HAM License, but most of these did not have much range and the ones that had good range were expensive and required a license. All of the units featured were 2.4 Ghz and were in my opinion were a bit too pricey for me.

After looking around a while, I found a Transmitter on the web that looked reasonable in price, lightweight, and powerful enough for range.

The Videolynx 434 was the best choice for this project. This unit transmits on a Amateur Television Frequency so my Technician Class Amateur License came in handy. (Required for this use)

The Videolynx 434 produces up to 100 mw PEP that can easily send a picture 0.25 to 8 miles depending on the type of antennas used to transmit and receive. The Videolynx 434 is available at transmitvideo.com or hamtv.com for $99.00 US.
 
 
The Videolynx 434 The Panasonic Board Style Camera Camera in 1” PVC cap housing
 
I now needed a video camera that would work well with the Videolynx 434 so I purchased a high quality Panasonic “Board Camera” to get the best picture possible. This camera was available from Supercircuits.com (Cat # PC87XS) for $100 and in my opinion worth every penny. I mounted the camera in a 1” PVC cap for protection and sealed it up with RTV silicone. I chose to use a 10.4 Volt 270 MA Ni-Cad battery to power the Videolynx and the board camera. I had to regulate the camera voltage to +5v with a voltage regulator (available from Radio Shack) mounted in the camera housing. I also regulated the transmitter power with a 9.1v-1amp Zener Diode and a 15 Ohm-0.5 Watt Resistor to keep the transmitter power constant.

I originally installed the system in a “Ugly Stick” ARF model for testing purposes and quickly found that I needed a platform aircraft that was large and stable enough to handle the extra weight. I purchased a Piper Cub J-3 45-60 size ARF from Model Tech (Hobby People) with it’s 900 square inch wing and 17 oz per foot wing loading, it proved to be the best set up for the money. In order to not interfere with the remote control receiver and cause a loss of control, I had to devise a shielding system to eliminate RF bleed over. The Cub was the best choice due to its size with room enough to separate the video system in the tail from the Remote control system in the cabin.
 
Antenna Diagram Transmitter in Shielded Enclosure Transmitter mounting location In bottom of tail section.
 
All of the linkages in the tail are nylon to prevent RF from running down the rods to the R/C receiver. I also put in a kill switch on a servo to kill video in flight in case of a loss of control situation. I experimented with video transmit antennas and believe that the Dipole type antenna built into the vertical stabilizer works the best for fixed wing aircraft. I used 50 Ohm RG-174 coax to feed the dipole that I built into the tail fin with a Sulivan pushrod cable and guide tube as a durable antenna vertical. The receiver (a cable ready TV tuned to channel 59) uses a homemade quarter wave ground plane antenna made from a type f coupler and 1/16” piano wire. The antenna should be put on a mast above head level to propagate the best line of sight receiving.

Details on receiving and transmitting antennas are available from PC Electronics web site at hamtv.com. I found that a TV/VCR combo is a good system for ease of portability and allows you to record your flights. Be aware that some different models may have more or less sensitive front-end receivers and may require a separate ATV Down Converter (Available from PC Electronics) I am currently using a Symphonic TV/VCR and can easily receive at 3000 ft. range with a quarter wave vertical. The Symphonic TV/VCR was an economical choice for me ($130 from Best Buy) but some may choose to purchase units that have more features like 12v adapter for field use or a small LCD monitor mounted on their R/C transmitter for this purpose.
 
 
Video taken of the Cajon Washbasin in San Bernardino CA at 1500’ elevation.
 
The final product is a video system that produces high quality, real time video that is a lot of fun. I am enjoying the aspect of taking flight with my model and finding it more interesting than any flight simulator I have tried. I am still experimenting with the system and hope to find new uses for it like a visual aid to be used for in-flight re-fueling from model to model. Videolynx is now offering a Video and Audio unit that allows you to put sound to your videos, something I hope to get into next.

If you have any questions on the details of this project, please feel free to e-mail me (Don G.) at: WEAZOL1@PRODIGY.NET
 
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