Households across Sheffield may experience disruption to their Freeview television as new 4G broadband is launched.
The new masts could disrupt Freeview received through an aerial, because 4G signals operate at adjacent frequencies.
Televisions and set-top boxes can fail to block the signals, causing loss of sound, distorted images and loss of some channels.
Independent organisation at800 is trying to ensure viewers can still watch Freeview or are offered a suitable alternative as 4G services go live, at no cost.
Ben Roome, at800 chief executive, said: “We’re helping viewers in the area and continue to offer support.”
Viewers experiencing disruption should call 0333 31 31 800, 0808 13 13 80 or visit www.at800.tv