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Old Sep 08, 2011, 07:41 PM
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Diagonal lines in the video

I'm getting diagonal lines in the video, even with the RX/Motor not connected.

The video system is powered by a separate 3S battery pack with a LC filter. The setup is

Battery -> Fy-AP117 OSD -> BevRC WDR700 camera -> Fy-Ap117 OSD -> Immersion RC 5.8 TX

All wires are twisted except the wires from the camera to the OSD but that was the same with the old camera

This didn't happen with the DX201 camera, is there a way of getting rid of the noise without replacing the camera?

http://www.youtube.com/watch?v=zDa3vMTukmU
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Old Sep 08, 2011, 08:32 PM
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ground loop?
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Old Sep 08, 2011, 09:54 PM
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Counting the lines and multiply by 15750, you'll have the beat freq. of the interfering noise.
Look like it's the 400-500khz range. Might be a defective on board step-down of the camera.

-Hugo
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Old Sep 09, 2011, 12:55 AM
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huge is a beast
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Old Sep 09, 2011, 05:17 PM
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I'm going to suggest you power the VTx at 2S (tap the balance lead for 7.4v).

Any improvement?

Nigel.
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Old Sep 09, 2011, 09:10 PM
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Australia, WA, Joondalup
Joined Jul 2008
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I think Devon is right.
I have seen this coming from the IRC Vtx.
To experiment, try powering the VTx with a separate 2S LiPo, it should clear up.
If the Vtx is connected to the camera with the same power supply this will happen every time.
Goodluck. Let us know how you go.
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Old Sep 09, 2011, 09:29 PM
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I saw it on the foxtech 5.8 Vtx, the onboard 3.3V step-down produced similar lines. Bad filtering design or something, I have two and both does this.

However, the IRC designer brag a lot about his attention to details so I doubt it could be the Vtx. Anyway, those lines are from switching power supply somewhere in your setup.
There's one in your camera and one in the Vtx.

Tip: Touch and hold the Vtx, look for change in the lines, do the same with other thing you may suspect.

-Hugo
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Old Sep 10, 2011, 03:19 AM
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I have this same 'herringbone lines' issue with onboard switching regs on another Immersion VTx and another well known VTx (not a Chinese product and the supplier is also well respected).

I made a test powering from a variable voltage linear power supply and you can see the differences here (click through to watch it directly on Vimeo in a larger screen)...

5.8GHz VTx problem (0 min 59 sec)



My gut feel is still with filtering as I had a similar problem on a homebrewed 5.8GHz setup...

Homebrewed 5.8GHz FPV rig - First light. (2 min 23 sec)



Improved filtering resolved it...

5.8GHz with improved video (1 min 2 sec)


Nigel.
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Last edited by Devonboy; Sep 10, 2011 at 07:02 AM.
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Old Dec 13, 2013, 11:46 AM
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I know I'm digging this up, but I have the same exact problem with my ImmersionRC 600mW 5.8 GHz Tx. Thanks for posting the video with the varying DC PSU, Nigel. I'll try powering my VTX off 2S. Would there be any issues in throwing my lipos off balance if I tap 7.4V off the balance lead of my 3S packs? I'd prefer to not add the weight of a second battery.
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Old Dec 13, 2013, 01:22 PM
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I haven't had any issues with tapping the main LiPo pack for lower voltages and low power consumption devices.

Nigel.
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Old Feb 16, 2014, 11:46 PM
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It is inconvenient to need to tap off the lipo balance lead. Has anyone tried adding more filtration to the TX PCB after the switching regulator (such as a larger inductor)?
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