The data streams, together with a number of other data streams 53, are processed and multiplexed by TDM multiplexor 54 to generate a multiplex data stream 55. This multiplex data stream may, for example, comprise the output intended for transmission over a selected frequency, for rebroadcast by a particular transponder on a particular satellite. Multiplexor 54 may preferably perform a time division multiplexing of the various data streams 51, 53 according to an appropriate protocol utilized by the DBS or other broadcast system.