Hundreds of thousands of televisions in many parts of the Anglia region will need re-tuning if they get their signals from the main Tacolneston transmitter or a Sandy Heath relay.
About 350,000 homes in Norfolk and north Suffolk get their terrestrial television signal from the Talcolneston transmitter. Satellite and cable television is not affected.
The main Sandy Heath transmitter in the west of the Anglia region is due to be adjusted on 17 July 2018 but some relays served by Sandy Heath are affected on 6 June.
People in Cambridge, parts of Luton and Northampton and the Kimpton area will need to re-tune their television on 6 June
The changes are being made to the transmitter network to transfer some of the frequencies currently used by television to mobile phones.
This is for Freeview viewers and those using other digital terrestrial TV services like BT TV and YouView.
Viewers may need to perform a retune of your set top box on Wednesday.
If you are having TV reception problems after Wednesday 6 June, you are advised to call the Freeview Advice Line free on 0808 100 0288.