Boronia is right. However, depending on the building’s layout and location relative to the transmitter, some people who have tolerated a slightly fuzzy picture on analogue may have problems. As analogue reception declines in quality you get ‘snow’ etc, but with digital there is a fairly ‘thin’ transition zone from the usual brilliant picture through intermittent pixellation to ‘no signal’. There are specialists in antenna installations for apartment blocks who can check your antenna and the various relays in your building. Even in my block in Sydney’s east, with all three transmitter sites visible from the roof, there can be some interference due to conventional antenna leads picking up adjacent channels from one of the other transmitters. Quad-core antenna leads can help with this.
From observation of the numbers of cathode-ray TVs (and even the huge projection units) put out for kerbside cleanups, there can’t be too many people still watching analogue.