The View Up Here

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Video KAP Rig – Status Update

Posted by Tom Benedict on 22/06/2013

It took a few weeks, but I finally had a chance to make some small changes to my KAP rig and give the video downlink another try. I had much better results this time – a clear indicator that my antenna mounting was suspect. But I got another clue, too. I’ll get to that in a sec. First, the current rev of the setup:

KAP Rig 2013-06-17

The new monitor is about the same size (and weight!) as my RC transmitter. With the exception of the extension cable on the antenna, the KAP rig is almost completely unmodified.

The ground unit is a little ungainly. The mounting arm was made for a much smaller monitor, so it wobbles around more than I’d like. I can fix this pretty easily by making a thicker one. The monitor mounts to it using a T-nut that rides in a slot on the back of the monitor, so even using a thicker arm won’t require changes on the monitor side.

The larger monitor had an added benefit: I found myself placing the ground unit on the ground, and looking at the monitor as I let kite line out to get over the subject. By pointing the camera down, I could tell exactly where the camera was, and once it was in position I could pick up the ground unit and aim the camera to get the framing I wanted for the photograph. Once I’d done this a few times, I decided the larger monitor was well worth the extra weight, encumbrance, and cost.

This second flight was over the Mala`ai garden in Waimea:

Mala Ai Garden - 2013-06-16

This time I flew with my Canon Powershot A650IS, but the rig will take a Gopro or my T2i DSLR as well. I’m running CHDK on my A650, which lets you use a bitmap as a focusing reticle. The reticle I’m using has the “rule of thirds” grid on it with circles around the intersection points of the grid. The reticle image is also sent through the video out on the camera, so the combination of the big screen, the reticle, and good wind made it very easy to position the subject in the frame just the way I wanted it.

The video glitching I was getting during my previous test was completely absent, even with the rig more than 500′ away from me. No surprise with this video Tx/Rx, but it was nice to finally see it work. The only real gotcha I ran into was that the antenna connector on the video Rx was corroded. CORRODED?! Yep. EVERYTHING is gold-plated except for that one connector. The nut that holds it in the case was showing actual signs of iron rust. GAAAH! So at some point I need to unsolder the crummy connector and put a better one on. But that’s for another time.

I’m not 100% happy with the extension cable on the transmitter antenna, so I’m trying to come up with better ideas. So far this keeps the antenna clear of the rig, well out of the camera’s line of sight, and low enough to always have clear air between it and the receiver. But something a little more robust would be good.

The wind this weekend is (yet again) questionable, but I’m bound and determined to get out at least once to do some KAP with the new setup. Whether I can will actually depend a lot on my cat, Ember. He’s slated to come home this weekend. Depending on how things go, I may be spending the weekend with him.

– Tom

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