James Theodore Gentry

US Patent:

45286604, Jul 9, 1985

Filed:

Dec 8, 1983

Appl. No.:

6/559611

Inventors:

James F. Gentry - Glen Burnie MD

Assignee:

The United States of America as represented by the Secretary of the Air
Force - Washington DC

International Classification:

H04J 602
H04J 310

US Classification:

370 80

Abstract:

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.