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Wireless Video For RC Aircraft

Wireless Video for Remote Control Aircraft               By Don R. Giandomenico N6YIY - April 20, 2002

Note: Since this article has been written there have been many advancements in wireless video technology. The electronics used in this article may be outdated and unavailable in the current market. This article remains on this site as a reference and record of the Wireless Video Project and should be cited accordingly.

       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 can’t 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’s 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 operator 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 prepackaged 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. I decided to experiment with an 434 MHz ATV transmitter called the Videolynx 434 (available from Transmitvideo.com) and this unit is what got me fired up about airborne video. This transmitter worked pretty well but required shielding from the receiver and did not offer sound at the time. After a few months of testing if found I needed a better solution for overall performance.
       Finally After looking around some more I found a Transmitter on the web that was reasonable in price, lightweight, and powerful enough for range. The AVX900T4 was my final choice for this project. This unit transmits on the efficient 900 MHz band and did not interfere with the 72 MHz remote control receiver. Unlike the popular 2.4 GHz Band, which has a lot of traffic and needs line of sight to work efficiently, the 900 MHz band is better suited for long range applications being a lower frequency.

This is the AVX900T4 transmitter. It runs on 12 VDC and draws about 250 Ma. The transmitter has video and audio inputs

The vent on bottom pulls cool air through the transmitter body keeping it cool.

I made a transmitter housing to hold and cool the transmitter as it generates heat when transmitting.

The housing mounts inside the Cub’s under body and the antenna is pointed at a 45 degree angle.

       The AVX900T4 transmits on an Amateur Television Frequency so my Technician Class Amateur License came in handy. (Required for this use) The T4 produces up to 500 mw PEP that can easily send a picture and audio 1 to 2 miles depending on the type of antennas used to transmit and receive. The AVX900T4 is available at Supercircuits.com for about $75.00 USD and a matching receiver (AVX900R1) is also available for $95.00 USD. Both the receiver and transmitter use “rubber ducky” type antennas but you can achieve better results employing a Yagi Beam Antenna for the receiver.
       I now needed a video camera that would work well with the AVX900T4 so I purchased a high quality Panasonic “Board Camera” to get the best picture possible. This camera was available from Supercircuits.com (Camera shown below has since been discontinued - Panasonic cat # GP-CX161-53P. A good substitute camera is the Supercircuits cat # PC75WR which runs on 12 volts and already has a lightweight aluminum enclosure)
      
I mounted the Panasonic camera in a 1” PVC cap for protection and sealed it up with RTV silicone. I chose to use a 12 Volt 600 MA NiCad battery to power the Transmitter 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. The camera is mounted on the left wing panel as to not be obstructed by the propeller.

This is the Panasonic board camera before it is housed in it’s PVC enclosure.

The PVC cap houses the camera nicely with room to spare.

The voltage regulator uses the camera enclosure back plate for a heat sink.

The clear protective lens is thin clear poly carbonate and is held in place with this flange.

       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. The Cub has room enough to separate the video system in the tail from the Remote control system in the cabin thus preventing radio interference in the receiver. 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.

This photo is a video frame taken from the Cub above the Cajon wash San Bernardino California.

       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. (AMA now requires that a pilot must keep direct visual contact with the aircraft being controlled at all times and not rely solely on video link systems.)  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 refueling from model to model ;0) See actual video from the video cub at:
                                                       The Video Cub

                             Also be sure to check out the new Sail-Cam Project!!!

These are some web sites of suppliers and communities:

http://www.supercircuits.com/

http://www.cctvwholesalers.com/

http://www.eyespyvideo.com/

http://rc-cam.com/

http://www.rc-cam.com/forum/

http://www.transmitvideo.com/

Questions or comments ? Feel free to contact me - Don Giandomenico

 

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