Frame synchronization for a channel with different data rates

In some communication links, different data rates are used at different times on the same channel and each is assigned a separate frame synchronization (sync) marker. The frame search is completed within a finite number of frame intervals once both phase-lock and bit-sync are achieved because the incoming data rate can change. The probability of failure to frame-lock, and an upper bound of probability of false frame-lock in a frame search mode are derived for a communication link with a 10^-5 bit error probability. The probability of failure to detect data rate change and the probability of false detection of data rate change in a frame-lock mode are discussed. In a frame-lock mode, the probability of failure to detect data rate change was equal to 0.12×10^-6 and the probability of false detection of data rate change was equal to 0.496×10^-11 . A frame-lock device can be used for the Space Station Freedom Ku-band return link