Projects @ S D F

SDF member Vince Jenkins, also an Amateur Radio operator (KC7IIU) for almost 10 years, has equipped his plane with Amateur Radio TV (ATV) to provide live video during flight. The small camera is mounted to the side of the fuselage with the antenna on the wing tip.  Side mounting provides more ground clearance than the original position he used under the fuselage.  Video is transmitted to a receiving setup on the ground, shown below, that converts the signal to one of the channels on a standard TV receiver.

Almost everything was built from kits or scratch. The TV transmitter was built from a kit from PC Electronics (www.hamtv.com) in CA. The Plane was a kit (modified PT-40) from Great Planes with a 60-size engine. The camera was plug and play, and everything else (antennas, housings, cables, etc.) was built from scratch.

The transmitter operates on 429.250 MHz with an output of about 750mW.  Video is supplied by a second generation CMOS color camera powered by 12V and has 380 lines of resolution. Case included, it measures about 1.50" X 2.25".

The transmit antenna is located on the tip of the left wing. It is a vertical oriented dipole. The receive antenna is a quarter wave vertical with 4 quarter wave ground radials extending from its base.  All are home made using 3/32" brass tubing for the active elements and 0.031" piano wire for the radials.

The video system in the plane is powered independently from the RC receiver. It uses 10 "AA" size nickel metal hydride batteries in series to generate the 12V needed for the camera and the transmitter.  They will provide power for around 4 hours of operation.

The side-mounted video camera takes live pictures for transmission to the ground. (click on the photos for a larger view)

A small antenna is mounted on the end of the wing.  Care is taken to shield and isolate the TV transmission system from the radio control receiver controlling the aircraft.

The receiving equipment consists of the following: a TV/VCR 13" color combo, a 12V to 120VAC converter (out of the picture to power the TV in the field), a 12V 13 amp-hour battery (also out of the picture) to power the converter for about 3 hours, a down converter to receive the plane's signal and put it on TV channel three, a smaller 12V battery to power the converter, and the appropriate cables to connect the whole mess together.

There have been a number of challenges in this project.  The biggest problem between the RC receiver and the TV transmitter came in the form of conducted radiation in the cabling. I shielded the RC receiver in copper foil and then grounded the foil to the ground of the receiver. This worked well for protection against airborne interference. As far as conducted radiation goes, I found that there was interference if any of the cables from the video system came in close proximity (within 1 inch) to any servo cables. Routing and placement of the video components was very important in the overall design and construction to maintain reliable control of the aircraft.