It happens on both the 570 and 562MHz. Signal strength is 100% on one of them, 97+ on the other.
Is there anyway on Tivo to check signal quality?
It doesn't seem to be weather related or tied to any appliances being turned on or off.
I wondered about posting this in the freeview or Tivo forum. the problem was first noticed sometime after we reinstalled sky and moved the Tivo to the bedroom. so there has been a combination of changes in the cabling (including the sky techs combining our Aerial and Dish feeds then splitting them again at one of the outlets) and of course the cables I terminated could be dodgy but it seems to only be on TV3/TV4.