Methods for synchronizing (d, k)-constrained sequences

Given a (1,7) code, a loss of synchronization may occur by insertion or deletion of a 0 or a 1. That event is catastrophic, i.e., it will cause an unlimited number of errors in the data since the moment of the loss of synchronization. We introduce two methods for recovering against insertions or deletions of symbols. The first one allows for identification of up to 3 insertions and/or deletions in a given block, permitting quick synch recovery. This method is based on variable length codes. The second method is of block type, and allows for detection of large numbers of insertions and deletions. Both methods can be extended to general (d, k) constrained codes.