Data transmitted over different channels may be updated by receiving one or more input data streams containing data for one or more digital data services, wherein the data is in the form of a plurality of packets, wherein each packet includes information identifying a channel and a number of related downstream packets; determining from the plurality of packets a time that an update packet containing data for one of the digital data services will be transmitted as part of the signal; and generating a schedule packet containing the time that the update packet will be transmitted as part of a signal.