Apparatus for identifying coded information without internal clock synchronization

摘要

A self-synchronized apparatus for recognizing identifying codes especially on missiles and spacecraft. The apparatus comprises a video quantizer for receiving bipolar video input signals and providing an output of validly timed data to a decode register which is clocked by a free running oscillator. The decode register defines a valid mark as "K" high bits followed by "K" low bits where 2K is the capacity of the decode register. A constant width decoder compares the first K bits in a sequential, pairwise fashion with the inverse of the values of the second K bits. The constant width decoder ANDs the pairwise comparison outputs to insure that "K" high bits are followed by "K" low bits before a "mark" signal is produced. A derivative data buffer receives the "mark" signals. A synchronous counter is coupled to the derivative buffer and the free running oscillator to produce one output pulse for every N oscillator output pulses. The inputs of the derivative buffer presets the sync counter to synchronize the derivative clock output with the actual data as transmitted.