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View Full Version : What are causing these lines in the video?



NDw
20th August 2011, 02:17 PM
I thought there was a similar thread on here but if there is I can't find it.

Anyway anyone have guess as to what are causing the lines in this vid.?

It's obviously not esc noise as the motor is not turned on yet.


http://www.youtube.com/watch?v=Sgm8qn3090w

TallyHoe
20th August 2011, 02:56 PM
It could be a switched mode PSU problem but no idea if your using one or not.

Could you describe your wiring at all? .. how various things are powered, how they are wired up etc.

Are you using screened cable for the video link from camera to video TX?

How close is the video TX's antenna to the camera?

This is assuming your transmitting live video from your aircraft.

NDw
20th August 2011, 03:45 PM
Yep using this (https://www.dpcav.com/xcart/product.php?productid=16615) switching psu as it is said not to cause interference with uhf. I guess that's step one to try.

Very basic wiring. No screened cable. Just wire coming off my 4s bat to the psu, the output from that goes to the cam and vtx. A video wire going from the cam to the vtx( the wires are all servo wire).


There's about a meter between the vtx and cam. And the same between the rc rx and vtx and cam.

Verid
20th August 2011, 05:25 PM
Had identical lines with LawMate 500mW vtx when used with supplied (on-cable) PSU. Problem gone when I changed 5V supply. If your setup can handle 12V try powering it directly from 3S. If it is 5V try using BEC (from ESC for example) That should give you an answer if it is power related problem or something else.

TallyHoe
21st August 2011, 04:07 AM
A meter of non-screened wire for the video line from camera to video tx is not a good idea.

You need to make that connection with a screened lead, preferably 75ohm thin coax for best video quality.

NDw
21st August 2011, 07:36 AM
Well in case I put anyone off the dpcav psu I've tested it right up against it and it isn't that.

Thanks I'll try shielding the video wire.

NDw
21st August 2011, 11:32 AM
So would I be beter off having shielking around just the video wire or around the vid, power and ground wires ( not shileded individually)?

TallyHoe
21st August 2011, 05:36 PM
I'd try just using some cheap screened lead just for the video signal from camera to video tx - for now.

If that doesn't help, then take a look at the power supply to the camera and video tx - noisy supply to either could cause what your seeing.

NDw
23rd August 2011, 10:03 AM
THanks so I tried a shielded video wire and it hasn't made a dif.

I suppose the next thing to try with be a ferrite ring net to the vtx?

Would IU wrap the video signal wire in the ring or the power wires or?

TallyHoe
23rd August 2011, 01:11 PM
Does it happen if all you have powered up is the camera and video tx ?

Bajas
23rd August 2011, 01:29 PM
I had simular picture problem on one of my lawmate 2.4 500mw tx... and it was that the in voltage was to higth.
The tx will opperate at from 5 to 5.5 voltage, but I have experiensed that it likes 5v much better then 5.5

volto
23rd August 2011, 02:06 PM
I had something similar, but the lines were tightly grouped and wavy. Solved by adding a small ferrite just on the ground wire to the vtx, less than 10cm from the vtx.

Danub
23rd August 2011, 03:22 PM
If you either use an LCfilter (sander style filter) on the power lines nearing the VTX That should clear up any switching noise within the system.
I have made them and they work well.
If you don't want to make your own then Tim at RMRC has LC filters for about $13
The filters worked wonders for me!!
I also throw out one possibility I have experienced in testing. . I am using a lawmate 2.4ghz 500mw vtx and ALWAYS have waves in my video when testing at my house. (it is interference from the neighbors WIFI setups)

BloomingtonFPV
23rd August 2011, 05:22 PM
Any idea what is causing these lines? There is an apartment complex that is generating wifi, potentially.

Video is 2.4ghz (2414)

I have clear video with no lines up to about 2 miles out, when these start. The clear white horizontal lines only happened when I turned around for the return.

I need to know if I can overcome this with better antennas or just jump to 1280 mhz.


http://www.youtube.com/watch?v=TJJKJrr0aCA

Note- gps was malfunctioning. I never got above 400' high or 700' away;)

jimmaplesong
23rd August 2011, 05:32 PM
I think it is, and it would be close to you, the receiver. If you make sure all your smartphones are in Airplane mode, and aren't right next to a house or business with wifi, it'll go away. I was afraid of wifi interference, but I'm about to make the jump to 2.4GHz myself. It doesn't show up on people's ground recordings nearly as often as I thought it would.

The other video where I've seen this sort of interference is from ReadyMadeRC:
http://vimeo.com/7788423

Keith
23rd August 2011, 05:50 PM
Bloomington, that definitely looks like some sort of digital signal, but it doesn't look like wifi. At least not the one I've see around here... ;)

NDw
24th August 2011, 07:19 AM
Thanks for the input. Yes I was getting the lindes with just the vtx and camera powered up, via the switching psu.

But not in my wiring harrness off the plane. Only when on. I tried wrapping the video wire around a ferrite and it did not good. So then put an lc filter on the output of the psu. (I've nvr needed an lc filter other before when the motor was not powered up).

But it seems to have solved it. I still get them sometimes but by moving the components around a bit they seem to vanish.

TallyHoe
24th August 2011, 09:10 AM
I was afraid of wifi interference, but I'm about to make the jump to 2.4GHz myself. It doesn't show up on people's ground recordings nearly as often as I thought it would.http://vimeo.com/7788423

Probably because most people I guess are out in the open fields when fpv'ing, and so are normally far away from the usual wifi access points etc.

TallyHoe
24th August 2011, 09:12 AM
Thanks for the input. Yes I was getting the lindes with just the vtx and camera powered up, via the switching psu.

But not in my wiring harrness off the plane. Only when on. I tried wrapping the video wire around a ferrite and it did not good. So then put an lc filter on the output of the psu. (I've nvr needed an lc filter other before when the motor was not powered up).

But it seems to have solved it. I still get them sometimes but by moving the components around a bit they seem to vanish.
Sounds like it's mostly due to your switching mode PSU then. They can be noisy buggers if they haven't bothered designing in any proper filtering (switched mode PSU's should also be fully screened).

NDw
5th December 2011, 06:43 PM
So this is a dif video, using a dif system and frequency. I'm getting lines with nothing but my cam(different cam) and an immersion rc vtx connected up. Any ideas anyone?


http://vimeo.com/33182817