A broadcast sender of data does not know when a receiver starts to,listen to the transmission .While for radio or television there is no problem,transmission of the other important information,such as traffic or weather conditions ,has to be repeated to give receiver a chance to receive this information after having listened for a certain amount of time.
The cyclical repetition of data blocks sent via broadcast systems is often called a broadcast disk according to the project in Acharya od data carousel,eg according to the DAB or DVB standatrds.The sender repeats the three data blocks A,B and C in a cycle.Using a flat disk , all blocks are repeated one after the another.Every blog is transmitted for an equal mount of time,the average waiting time for receiving a block is the same for A,B and C.Skewed disks favour one ofr more data blocks by repeating them once or several times.Thsi raises the probability of receiving a repeated block ,if the block was corrupted the first time.
Finally ,multi-disks distribute blocks that are repeated more often than others evenly over the cyclic pattern.This minimizes the delay if a user wants to access .
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