# Electromagnetic Interference

## Introduction

Electromagnetic Interference (EMI) can occur between your tablet and other devices. 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 of 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 a warping caused by a magnet. This this case it was a magnet attacked 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 interference can also present as a region where pen seems unable to make a mark. Notice that some warping is also present. In this case, the causes was that the tablet was resting upon 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 will act like a pen and control 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


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