To avoid baseline wander, the same number of zeros and ones are transmitted on average. Such DCbalanced data is ensured by choosing an appropriate encoding scheme. This encoding also ensures a sufficient regularity of transitions in the encoded data pattern for downstream PLLs to acquire and maintain lock, enabling clock recovery at the receiver.
Many encoding methods specified by serialdata standards (such as 8B/10B encoding) and standard PRBS patterns produce 50% DTD on average. Therefore, DTD=0.5 is generally a good assumption. An obvious exception would be an 1010 (repeating) clocklike data pattern, for which DTD=1.
