|Pixelation which can happen because of TV
Apparently this is a well-known problem. The signal to TVs and Freeview boxes can be blocked by these 4G mobile signals as the 800 MHz frequencies used are next to the frequencies used for Freeview.
Although it is irritating, the good news is that you can get the problem sorted for free.
The company www.at800.tv has information to help you diagnose for yourself whether it is likely that your TV signal is suffering because of interference from a mobile phone mast. Alternatively you can ring them for free from a landline or mobile on: 0808 13 13 800. If necessary they will send out an engineer who will check whether you need to have a filter and install one as appropriate for FREE!