G. Clifford Carter
G. Clifford Carter’s pioneering contributions to determining and using coherence and time-delay estimation have had lasting impact on the field of signal processing including sonar detection, classification, and localization. Dr. Carter’s algorithms are used today in applications ranging from underwater acoustics for the U.S. Navy’s submarine fleet to healthcare. Dr. Carter’s research on generalized correlation methods for time-delay estimation resulted in what is considered a landmark paper in the signal processing field. Published in 1976, he presented powerful methods of statistically optimum processing for estimating the relative delay of a random signal received by two sensors in the presence of noise. The generalized correlation algorithm became one of signal processing’s most fundamental algorithms and is still used in numerous signal processing systems. Dr. Carter’s pioneering work on defining and statistically characterizing the coherence function and providing an algorithm was significant to the development of high-definition sonar. He determined the limitations on length and resolution for sonar arrays necessary for handling partially coherent oceanic noise fields. Dr. Carter provided an understanding of how to measure signal coherence in these noise fields and determine confidence limits. His automatic coherent processing algorithms are used in the U.S. Navy’s acoustic surveillance processing systems. His more recent patented work includes a close-range sonar system that provides sufficient warning to allow maneuvering to avoid collisions, overcoming the signal processing problems presented by ship’s own noise.
An IEEE Life Fellow, Dr. Carter retired from the Naval Undersea Warfare Center Division Newport, Newport, R.I., in 2009 as a senior technologist for acoustic signal processing.