Abstract: A multi-channel automatic transmission system, which is used with a number of regional transmitters, replaces functions previously performed in a network studio by a number of single channel automatic transmission systems corresponding to the number of regional transmitters. Outputs from either a computer or a manual input device are selectable by a switch to operate the system in accordance with a stored first selection of commercial messages, a manually determined second selection of commercial messages, or a manually altered selection. The duration and commencement of the commercial break is the same throughout the network but the number, duration and sequence of the commercial messages transmitted by each regional transmitter can be different.

Abstract: A method of merging playlists each for a single channel for simultaneous transmission over a network by a multi-channel automatic transmission system (1) which replaces the functions previously performed in a network studio (100) by a number of single channel automatic transmission systems (111, 112, 113 . . . ) corresponding to a number of regional transmitters (101, 102, 103 . . . ). Any proposed merging is checked before the merged playlist is completed. The checking takes the form of two sequentially applied tests. The first test is that the required number of cassette changes be less than or equal to a calculatable maximum number. The second test is that for each channel, for each event other than the first event on the playlist, the sum of the cummulative thread, cue and pre-roll times and the elevator movement times be less than or equal to the sum of the total event durations including the event being checked less the total of the previous event durations for that channel.