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THERE IS A NEED FOR DEVELOPMENT OF A COMMERCIALLY AVAILABLE ECONOMICAL ACOUSTIC DOPPLER BACKSCATTER INSTRUMENT WHICH CANBE EASILY DEPLOYED AND USED TO SIMULTANEOUSLY ACQUIRE CURRENT PROFILE DATA AND BACKSCATTER AMPLITUDE INFORMATION RELATING TO PARTICLE CONCENTRATIONS IN THE WATER COLUMN. THE RESEARCH PROPOSED IN PHASE I IS DIRECTED AT TWO AREAS OFDOPPLER BACKSCATTER MEASUREMENT WHERE ADVANCES IN EXISTING TECHNOLOGY MUST BE ACHIEVED IN ORDER TO PRODUCE AN INSTRUMENT WHICH CAN MEET THE NEEDS OF A WIDE VARIETY OF USERS. WE INTEND FIRST TO EXAMINE A NEW SIGNAL PROCESSING TECHNIQUE FOR ACCURATE ESTIMATION OF DOPPLER FREQUENCY SHIFT IN THE BACKSCATTER SIGNAL RETURN FROM A VERTICAL SLICEOF THE WATER COLUMN; AND SECOND, TO EXAMINE THE EFFECTS OF GAUSSIAN AMPLITUDE SHADING OF THE TRANSDUCER ARRAY IN ELIMINATING THE UNDESIRABLE EFFECTS OF TRANSDUCER SIDE LOBES ON THE DOPPLER FREQUENCY MEASUREMENT. WE PROPOSE TO USE COMPUTER MODELING AS AN AID IN OPTIMIZING BOTH THE SIGNAL PROCESSING CAPABILITY AND THE TRANSDUCER DESIGN PARAMETERS. WE PROPOSE TO USE COMPUTER MODELING AS AN AID IN OPTIMIZING BOTH THE SIGNAL OF THE COMPUTER MODEL AND FINALLY TO SPECIFY AN INSTRUMENT DESIGN TO BE DEVELOPED AS PART OF THE PHASE II PROGRAM.