Apparatus for identifying coded information without internal clock synchronization

Abstract

A self-synchronized apparatus for recognizing identifying codes especially n 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.

Dependencies are inferred from the claim text.