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Old Jul 18, 2014, 02:50 PM
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Video interference with UHF?

Hello, i just got myself a fox800 1.3 video tx, with a ibcrazy mad mushroom on it and a lawmate R1200 receiver with a ibcrazy helical 5 turn antenna. Using orangeRx LRS 433mhz 1w system on my radio.

I made my first try today, it was terrible, the plane was literally uncontrollable.
At my first attempt, i launched it and plane was turning right while i was trying to turn left, managed to land crash.

At second attempt, i managed to launch it properly, but it was a pain to control.
. (4 min 57 sec)

At 4:00, i was holding the radio stick left, and it was NOT turning at all.

There was wind, but ive alway flew on wind with a 5.8ghz video setup, and never had problem before, i was also flying on 3d mode, while ive never tried it before, only 2D mode, could it be the reasons? Or could it be caused by the new video gear? I dont really dare to try again without knowing the issue.

Thanks
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Old Jul 19, 2014, 03:19 AM
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Well when I try a new flight mode on an autopilot, I always get the plane in the air first under a mode I know works, and turn it on THEN. If it goes awry you can put it back in a different mode. Why didn't you try it?
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Old Jul 19, 2014, 08:24 AM
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Change one thing at a time, test, get it working perfectly. Then change something else. Post a photo of you plane's setup and you might get some more answers.
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Old Jul 19, 2014, 12:12 PM
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Originally Posted by cantremember View Post
Well when I try a new flight mode on an autopilot, I always get the plane in the air first under a mode I know works, and turn it on THEN. If it goes awry you can put it back in a different mode. Why didn't you try it?
So flying mode can actually make the plane uncontrollable? I guess i should try 2D mode and No mode at all.
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Old Jul 19, 2014, 12:15 PM
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Originally Posted by Liquidsilver View Post
Change one thing at a time, test, get it working perfectly. Then change something else. Post a photo of you plane's setup and you might get some more answers.
Phantom Fx61 with stock motor and servo, 5000mah 3s battery for motor, osd and video, Ibcrazy turnstyle antenna under wing, Vector OSD, Fox800 1.3 with mad mushroom
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Old Jul 19, 2014, 12:24 PM
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I have the same OrangeRX OpenLRS and Fox800 vTX on my plane. If you haven't already, consider flashing with OpenLRSng. It has a spectrum analyzer tool. You can use it to see what noise/interference your video transmitter is producing. You can move things around physically, and/or move your hop channels around to avoid problem frequencies. It's very useful! However, in my case, I found that the vTX produced absolutely no issues. My telemetry radio on the other hand...

edit: oh and are you using PPM to your flight controller? The default PPM timing setting on the receiver was causing issues with my APM. It would work okay for a while and then a servo would "lock up" for a second or two.
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Old Jul 20, 2014, 02:17 PM
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Ok so i had trouble with the firmware with my orangerx but its fixed now, and yes i was on custom firmware, im using standard flight controller, at least how its configured on vector wizard.

So i plugged everything just like if im going for a flight, and put the helical antenna right next to my radio. Im getting these spectrum, i have no idea what they mean. And im using 12 hop channel.
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Old Jul 20, 2014, 02:53 PM
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I would definitely research the PPM timing thing. It might be specific to the APM flight controller, or maybe yours is finicky with the timing as well.

Anyhow, with the spectrum analyzer, you want to click "display hop channels". This shows what frequencies your radio is using. I'm by no means an expert on this, but this is how I understand and use this tool:

With all of your gear off (except the receiver connected to the spectrum analyzer), observe the graph. This is your noise floor. Power up your vTX. Notice any difference? Put the antenna of your radio (connected to the spectrum analyzer) closer to the vTX. Observe the graph. Try different vTX channels.

From the position of your LRS receiver antenna, you want the graph line to be as low as possible near your hop channels.
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Old Jul 20, 2014, 06:05 PM
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Here's what I get from about 18 inches away from my Fox800 (caseless, with cheap CP antenna).

ps. I had my grounstation LCD on nearby when I took these readings. When I turned it off, the noise floor dropped noticeably. Interesting, but for this purpose I only care about the interference on my receiver antenna in the air.
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Old Jul 20, 2014, 09:33 PM
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So i gave it a try for video channel, and channel 4 1080mhz is the most stable, i tested with everything connected and the radio TX right next to the Vtx, i get this

But when radio is away from the vtx, line move higher up to 60.
Does that look OK?
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Old Jul 23, 2014, 01:42 PM
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Originally Posted by insistent View Post
So i gave it a try for video channel, and channel 4 1080mhz is the most stable, i tested with everything connected and the radio TX right next to the Vtx, i get this

But when radio is away from the vtx, line move higher up to 60.
Does that look OK?
I think so? Personally I would move the hop channels that are on the spikes but I think it would be completely fine. How's it look when you use the video channel you had trouble on?
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Old Jul 23, 2014, 01:56 PM
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Originally Posted by genix View Post
I think so? Personally I would move the hop channels that are on the spikes but I think it would be completely fine. How's it look when you use the video channel you had trouble on?
On the other channel i used? It had an average of 60-80, but less spike.

Though the best video channel didnt helped with the control problem, yesterday i launched my plane, and it turned to the right itself to a crash, i could not control it from there.
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Old Jul 23, 2014, 02:03 PM
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That's sh*tty....and sounds just like the experience I had. Again, I'm pretty much a noob, but I don't see anyone else chiming in to help you so...

The next thing I would try is removing the PPM timing variable and potential issue by connecting via normal PWM to your flight controller. Or removing the flight controller all together until you're confident that you have a solid control link.
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Old Jul 23, 2014, 05:01 PM
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My flight controller is the Vector itself, it is currently on standard non ppm setting, its really since i swapped to a 1.3ghz video that messed up everything...
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