<p>If enough current flows and two ground pads are far enough apart, there might be a voltage difference between them because of the resistance in the PCB:s traces. That's called a ground loop.</p>
<p>As for why that causes noise; if the camera and the VTX have different reference points, a signal sent from the camera won't be received correctly by the VTX, and since a PAL or NTSC (The types of video that is used for analog FPV systems) signals use less than one volt, even a small in potential can cause video noise that will appear as horizontal bars moving vertically.</p>
<p><a href="https://www.epanorama.net/documents/groundloop/video_isolation.html" rel="nofollow noreferrer">Here is an some more information if you would like to read more about it</a></p>

CC BY-SA 4.0
2020-04-14T21:06:53.333Z
Excellent, thank you for that explanation
Drones and Whatnot
CC BY-SA 4.0
2020-04-14T21:12:47.877Z
No problem. I'd be happy if you marked this as the answer if you think it is!
Hannes Hultergård
CC BY-SA 4.0
2020-04-14T21:15:40.367Z
I’m going to leave this question open for a little longer to invite more answers, however I feel that you have explained it very well so will be happy to mark this as the answer shortly. Thanks!
Drones and Whatnot
CC BY-SA 4.0
2020-04-14T21:06:15.293Z
2020-10-31T00:15:52.590Z
2020-10-31T00:15:52.590Z
Hannes Hultergård
<p>To reduce video noise, it is often recommended to add a common ground between VTX and camera to avoid ground loops. What is a ground loop, how does it add video noise and how can a common ground negate its effects. Thanks.</p>

<hardware><multirotor>
What is a ground loop and how does a common ground reduce video noise?
Drones and Whatnot
# What is a ground loop and how does a common ground reduce video noise?

(Asked by: username_0 on 2020-04-14)

To reduce video noise, it is often recommended to add a common ground between VTX and camera to avoid ground loops. What is a ground loop, how does it add video noise and how can a common ground negate its effects. Thanks.

**Tags:** hardware, multirotor


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## 1 answers

### Answer by username_1 on 2020-04-14. Score: 5 | Accepted answer

If enough current flows and two ground pads are far enough apart, there might be a voltage difference between them because of the resistance in the PCB:s traces. That's called a ground loop.

As for why that causes noise; if the camera and the VTX have different reference points, a signal sent from the camera won't be received correctly by the VTX, and since a PAL or NTSC (The types of video that is used for analog FPV systems) signals use less than one volt, even a small in potential can cause video noise that will appear as horizontal bars moving vertically.

[Here is an some more information if you would like to read more about it](https://www.epanorama.net/documents/groundloop/video_isolation.html)

> **Comments:**
> **username_0**: Excellent, thank you for that explanation  
> **username_1**: No problem. I'd be happy if you marked this as the answer if you think it is!  
> **username_0**: I’m going to leave this question open for a little longer to invite more answers, however I feel that you have explained it very well so will be happy to mark this as the answer shortly. Thanks!  

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