> For the complete documentation index, see [llms.txt](https://docs.sevenpens.com/drawtab/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.sevenpens.com/drawtab/guides/general/electromagnetic-interference.md).

# Electromagnetic Interference

## Introduction

Electromagnetic Interference (EMI) can occur between your tablet and other devices. These devices could include cell phones or keyboards. It doesn't even really have to be a device. Sometimes ordinary non-electronic objects have magnets inside them that can interfere with a tablet.

## Effects of EMI

### **Jerky or stuttering pen position tracking**

EMI can make the pen have jerky movements - making the pen unresponsive for a few tenths of a second and then the pointer will catch up.

### **Warped regions due to Magnets**

Sometimes the EMI takes the form of a region that warps straight lines. Below is an example of such warping caused by a magnet. In this case, it was a magnet attached to a stand underneath the tablet. ([See this reddit thread](https://www.reddit.com/r/huion/comments/13yef7f/kamvas_13_digitizer_problem/))

<div align="left"><figure><img src="/files/k7zDaELum1EDCu5yEpbT" alt="" width="563"><figcaption></figcaption></figure></div>

### **Skipped regions**

EMI can also present as a region where the pen seems unable to make a mark. Notice that some warping is also present. In this case, the cause was that the tablet was resting on a laptop keyboard. Note that there is also some warping of the pen position. ([See this reddit thread](https://www.reddit.com/r/XPpen/comments/14joyq5/pen_skips_across_the_screen_in_certain_spots_help/))

<div align="left"><figure><img src="/files/4TD7xOu5qNMYzZOpSTlb" alt="" width="312"><figcaption></figcaption></figure></div>

## Tablets interfering with other devices

Sometimes it is the tablet that is interfering with another device.

Examples:

* A wireless mouse might have trouble working near some tablets.
* A tablet might interfere with your WiFi network connection
  * See: [TSG: WiFi and Internet problems with drawing tablets](/drawtab/troubleshoot/tsg-wifi-and-internet-problems.md)

## General weirdness

Weird things can happen. I have a keyboard that, when I unplug its USB-C cable, acts like a pen and controls the position of the pointer on one of my tablets.

## Magnetized desk surface

There are computer desks that are made of metal and deliberately magnetized. These can interfere with your drawing tablet. See:

* <https://www.reddit.com/r/wacom/comments/1af10hs/my_whole_desk_is_a_magnet_what_do_i_do/>

## iPads and cases

Some iPad cases have magnets in them, and they can interfere with the proper functioning of an Apple Pencil.

[/r/iPad - Some magnetic cases may interfere with the Apple Pencil Pro](https://www.reddit.com/r/ipad/comments/1d93ew0/some_magnetic_cases_may_interfere_with_the_apple/) 2024-06-05