# 2.18 Testing unwanted emissions function

A sanity check on the unwanted emission calculation can be done by using the &lt;Test Rel. Unwanted***&gt;*** emission function in the menu bar of SEAMCAT, by clicking on the icon of the toolbar ( [![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/Vp4YhOGoHBLqehVC-image.png)](https://wiki.cept.org/uploads/images/gallery/2026-04/Vp4YhOGoHBLqehVC-image.png) ) or by pressing &lt;<span data-highlighted="true" data-vc="highlighted-text"><span class="_kqswh2mm"><span class="_5pioz8co _189e1dm9 _1il9buyh _19lc184f _d0altlke" data-testid="definition-highlighter">CTRL</span></span></span>+SHIFT+U&gt;. The definition of unwanted emissions mask can be checked by calculating the actual unwanted emissions for given mask in a given <span data-highlighted="true" data-vc="highlighted-text"><span class="_kqswh2mm"><span class="_5pioz8co _189e1dm9 _1il9buyh _19lc184f _d0altlke" data-testid="definition-highlighter">VLR</span></span></span> bandwidth applying a certain ILT-<span data-highlighted="true" data-vc="highlighted-text">VLR</span> frequency offset:

![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/mt3NUFceAWwfBWrk-image.png) **Figure 55: Access to testing unwanted emission function**

This feature allows to directly extract the unwanted emission by entering the frequency separation, the receiver bandwidth and the spectrum mask as shown in Figure 56.

![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/zqRcg6fYmmqVJ0Dn-image.png)**Figure 56: Illustration of the unwanted emission function check routine**