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Live Video from a Model Plane

Basics

Recently, I've been interested in trying to send live video from my Zagi-400. I came across a web site that describes one guy's Electric Mongo Jr. with a video camera. I've made a couple of experiments with a disposable camera and a cheap digital camera that, while not live, have still been pretty fun.

Many of the video transmitters I've found require an Amateur (Ham) radio license  I knew I got my license for something! The most straightforward technique for broadcasting live video involves transmitting on 2-meter, hooking an antenna up to your cable-ready-TV, and tuning to a cable TV channel (usually CH59 or CH60 ). Alternatively, you can use a downconverter to transform the signal to CH2, 3 or 4.

Hardware

The best camera I've found so far is BCBW-1.

  • Image sensor: 1/3" CCD 514h x 492v pixels
  • Electronic iris 1/60 to 1/50000 sec
  • Automatic Sensitivity 0.03 Lux
  • Lens: 4.3 mm fixed
  • Resolution: 430 lines
  • Gamma: 0.45
  • Video output: 1V p-p neg sync composite
  • NTSC Video
  • S/N ratio 45 DB minimum
  • Power supply 9-12V DC, 100 mA. nominal consumption
  • Size 1.15" X 1.15" X 0.9"
  • Operating temp: -20 to +70 deg. Celsius 0-95% RH
  • $125

But elsewhere the size is listed at 1.75" x 2.75" so I may end up using this one instead. The specs seem remarkably similar, though, so I'll bet they're the same one.

I'm considering two different transmitters:

The VideoLynx:

  • Size: 0.63" x 0.8" x 2.25"
  • Weight: 1.5 oz
  • Power: 50 to 100mW PEP
  • Estimated range: 1000 feet, better with real antennae
  • B/W or Color
  • Fully enclosed
  • $100

The ATVJr:

  • Size: 1.75" x 2.75" x ? (PC board so probably ~.75" max)
  • Weight: < 2 oz.
  • Power: 0.5 to 1 W
  • B/W
  • PC board, no enclosure
  • $62

On the ground I'll also need a cheap portable TV, an antenna, and a downconverter

  • Size: 2.5" x 4" x 1"
  • Power: 11 to 20 V DC, 30 ma.

The specs aren't as crucial here since this stuff will be on the ground. Small & light are still good though as I'll need to haul them up the hill.

Power Consumption

To save weight, the motor, servos & receiver, and transmitter should all run off of the same battery. I'm not too worried about the servos & receiver, which draw fairly negligible loads (in comparison, anyway). The North Country web site doesn't list current specs for the ATVJr, but they do for their more full featured, 2W transmitter: 450-500mA. I'm guessing that this transmitter will draw 350 mA or so. The camera draws 100 mA. At this rate, my 500 mAH battery should run for over an hour (given strong enough wind to stay aloft without running the motor). This totally pales in comparison to the motor, which at full throttle can drain the battery in 10 minutes (roughly 3A).

Questions

  • How big is the camera, really?
  • Is an enclosure required? (Shielding is, I know)
  • What's wrong with my power consumption guesstimate? Is 350 mA a good guess?

Links

http://www.northcountryradio.com
http://www.hamtv.com
http://www.transmitvideo.com
http://www.smarthome.com
http://www.hicam.com.au
http://www.rc-cam.com                    - good homebrew info
http://www.blackwidowav.com           - a complete system