be the only solution. (Choosing an unused subchannel number [i.e. 30.99] on that major channel number [i.e. 30] may avoid the remap on existing subchannels [i.e. 30.1] and force the tuner to listen on that physical channel.) This has often happened in the U.S., where stations (especially LPTV) find it easiest to place their digital operations on a vacated analog channel. The same problem also occurs when the same station moves its digital transmission back to its old analog channel. There is no way to delete a station from the internal channel map, and a re-scan may be needed; or if the new physical channel is found, it may leave the old mapping in place, causing duplicate channels that cannot be accessed through direct entry of the numbers without also pressing the channel-up/down buttons. Many modern TV sets do an ACMS scan automatically as part of the setup process the user is guided through when the device is initially plugged-in. While early sets often lost their memory in a power outage or by otherwise being disconnected from mains electricity, all of them now have non-volatile RAM or a backup of some sort. Television technology