Efficient skew codes constructions

In communication channels consisting of many parallel sub-channels operating synchronously, the retrieval of data from all sub-channels form the message. Data can arrive at different times from the different sub-channels and it is possible that data from the next message is received before the completion of the current message. Skew detecting and tolerant codes can be used in such cases. We propose more efficient skew codes and introduce lower bounds on the number of the required check bits. The necessary and sufficient conditions for (t,d)-SD-codes are stated in the theorem given