A method and system for detecting frame slips due to loss of
synchronization in a digital communication channel is described. In an
illustrative embodiment, a synchronization bit pattern is periodically
embedded in the digital data stream. In a described embodiment, the sign
bits of the octets of every N frame of data is robbed to form a periodic
control channel carrying the synchronization bit pattern. The control
channel can be monitored at the appropriate intervals to detect the
appropriate synchronization bit pattern. Failure to detect the
synchronization bit pattern at the appropriate interval indicates a loss
of synchronization such as a frame slip.
