In transmission systems whereby data packets of a single type and having a fixed structure are used to transmit a given type of information, the invention optimizes the transmission by utilizing data packets of the same type to transmit information of different types and by differentiating the information transmitted in such packets by the rate of re-transmission thereof. In an application of the invention to RDS systems, the block PS is used to transmit both the program service name, as usual, and the radio text, and arrangements are made for the rate of re-transmission of the service name to be high and that of the text to be low, or possibly zero.