CHANNEL 4 has confirmed the exact date it will no longer be available on some Sky and Freesat TV boxes.
The firm is following in the footsteps of BBC and ITV, which have already made huge changes to how they broadcast on satellite.
Many are moving away from old SD (standard definition) and converting to HD (high definition) only.
Most viewers are unaffected but those with older set-top boxes will have to upgrade to continue receiving Channel 4.
These boxes rely on soon-to-be-obsolete broadcasting technology unable to deal with HD.
Across November, regional variants of C4+1, E4 Extra, 4Seven, E4 (SD), More4 (SD), Film 4 (SD) become unavailable to users of these legacy Freesat and Sky devices too.
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But the SD version of Channel 4 will be no more on satellite this month.
And the company has confirmed the exact date to The Sun that viewers need to be aware of - November 28.
It's important to note that the changes only affect satellite, so an SD version of Channel 4 will continue to exist on Freeview / YouView.
There are also no changes to Virgin Media.
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The number of affected households is very small, Channel 4 says.
"We are changing the technology we use to broadcast our channels to Sky and Freesat households – ensuring we are delivering the highest quality HD viewing experience to all, and, opening up the potential for new services in the future," a spokesperson told The Sun.
"With Sky customers being encouraged to move to HD boxes, this will affect only a very small number of viewers.
"This follows similar moves by ITV and Sky earlier this year.
"All our channels, along with a wide range of on-demand content, are also available on Channel 4 streaming via smart TVs, mobile, tablets and PC’s.
"Sky customers are able to upgrade to new equipment at no cost.
"There are no changes on Freeview and Virgin Media, plus, satellite viewers with HD boxes are unaffected."
Why are channels disappearing?
Analysis by Jamie Harris, Assistant Technology and Science Editor at The Sun
Fear not - your favourite channels aren't shutting down, it's just a change to the broadcasting technology.
This means some older boxes may not be able to receive popular channels anymore.
This largely affects boxes that are not HD-capable.
You can't buy these boxes anymore - the ones sold these days are all HD capable because HD TVs are commonplace now.
As such, the move isn't expected to affect a massive load of people but you might want to check if you've not bought a new TV set-top box in quite some time, so you don't have a nasty shock on November 28.