Monday, November 5, 2012

FPV- A couple steps closer

So far it seems like getting an FPV quad up in the air consists mostly of soldering a lot of cables together.

Ground Station Progress

Cut Video RX power cable in half, then added an EC3 connector

DC Power plugs for the portable DVD player
I was able to find a great deal on a portable DVD player on Craigslist. This seems to be a great option for a ground station monitor- just make sure it has a video input. The Magnavox I found for $20 has both video input, built-in batteries, and runs off of 9V DC. I removed the battery which dropped the current consumption considerably. Also, so far, it seems like it runs just fine off of a 11.1v 3s LIPO battery. The only annoying thing is that each time you turn on the DVD player, you must manually switch it to video in. Perhaps some surgery on the unit will fix that.....

Another note is that the video RX and DVD player both use 3.5mm 4-pole cables- which are very, very hard to find anywhere locally. These cables look just like headphone cables, but with an additional pole. MCM Electronics has a bunch of very reasonably priced cable options

I have a composite video to SD card video recorder on order, also from MCM. This will be very nice for post flight (crash) analysis.

Composite Video to SD Card Converter with AudioMCM Part #: 58-16090  |  Vupoint Solutions Part #: DVC-ST100-VP-BX2

Magnavox portable DVD player (from Craigslist, $20) connected to Video RX (upper center) and power panel (left). See the live video feed on the monitor!
Back of power panel. Fuse- to prevent big problems in case of a short. Lighted power switch, and two barrier strips. Below are the power leads for the DVD player and the video RX. There is room on the panel to also add power leads for the upcoming video recorder.

Nice bonus- Video RX + DVD player on only pulls 0.8 amps. (with DVD battery removed) It'll run for plenty of time on standard size 3s LIPOs.

Where to mount the ground station? How about this sweet (and cheap) soft sided suitcase from IKEA!

A couple rivets and velcro should do nicely to hold all the ground station components in place.

Quad-Copter FPV Progress
Camera with wiring harness, before modifications
Video TX, before modification.

Connecting the camera to the video TX couldn't be easier. Connect the camera power leads (red and black) to the power output on the video TX- red and black part of the large group of multi-color wires. Then connect the composite video leads- yellow on the video TX cable bundle, and white on the camera's cable. That's all there is to it. The camera now has power, and the video TX now has a signal. I used some male and female break-away headers from another project to make home-made plugs.

Home-Made connectors using "break away headers" - these were secured together using electrical tape once installed on the aircraft
I'm still trying to get Hobbyking to send me the OSD module that was missing from OSD package. Whenever that shows up (hopefully this year!) it'll also get wired in to the composite video lead. The OSD will provide some very valuable data- namely flight pack voltage and a return to home vector. Both of these pieces of information  will be overlaid on the video that is broadcast to the ground station. Until that is in place I'll have to depend on the low voltage alarm that is currently mounted on the quad. 

Next step, provide power for the video TX. Since this is going to be a very basic FPV setup with limited range and capabilities, I chose to save cost and weight and powered the video system from the main flight battery. A more robust route would be to use an additional battery pack. This particular camera and video TX like 12v DC, so the 11.1v 3s flight pack works just fine.

Added additional JST connector to Quad power distribution board to power the camera and video TX

Camera and Video TX, powered up by the Quad's onboard power
Next steps- build a camera mount. Ideally it'll accommodate the low-resolution FPV camera as well as a second HD camera, eventually a GoPro or similar.

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