Multiplexed data stream monitor

摘要

A multiplexed data stream monitoring circuit comprises a random access memory for receiving and storing a multiplexed data stream which is transmitted together with a synchronization signal and a data clock. A counter circuit is reset by the synchronization signal and counts the data clock signals to accumulate counts uniquely identified with signals within the data stream which counts are used to address the random access memory. For each accumulated count within the counter circuit, the corresponding accumulated count location is addressed in the random access memory to read the immediately preceding state of the current signal within the multiplexed data stream. The current data stream signal and the immediately preceding data stream signal as read from the random access memory are compared by gating circuitry to identify characteristics of the data stream. State changes of the signals within the multiplexed data stream are identified if the gating circuitry comprises an EXCLUSIVE OR gate.