MRM-503 MARKER RECEIVER 



50ft (15.2 m.) 



Figure 6.--Test arrangements at Catalina Island. 



takes of 10 to 15 seconds duration were made 

 through the use of a diver-operated l6-mm. 

 Bell and Howell camera. Attempts at photo- 

 graphing the television monitor screen were 

 unsuccessful owing to lack of synchronization 

 between the frame rate of the monitor. To 

 provide time synchronization between the tape 

 recordings and the motion picture film, a 

 crude but effective technique was employed: 

 a Straza Industries MRM-503 Marker Re- 

 ceiver was used for listening to the noise the 

 cameraman made when he tapped a screwdriver 

 against the face plate of the camera. The 

 motion picture shows clearly the screwdriver 

 striking the face plate of the camera housing, 

 and the resulting click was recorded on the 

 second track of the tape recorder. The distance 

 from the diver cameraman to the hydrophone 

 was 60 feet (18.3 m.). The time lag between 

 the arrival of the pulse and the occurrence 

 of the event was therefore constant and less 

 than one camera frame (24 frames/second). 

 The conclusions from the Catalina tests are 

 given below. After the processed l6-mm. film 

 from the Catalina tests was viewed, the various 

 fish species of interest were identified as 

 California sheephead ( Pimelometopon pul- 

 chrum ), kelp bass (Paralabrax clathratus). 



senorita ( Oxyjulis californica ), and halfmoon 

 (Medialuna californiensis). 



FEASIBILITY TESTS OF METHODS OF 

 DATA EVALUATION AND REDUCTION 



The following paragraphs delineate the var- 

 ious techniques that were used to extract the 

 data from the tape-recorded tests from Mission 

 Bay and Catalina Island. The associated block 

 diagrams and setups of each method are 

 included. Several techniques were used in an 

 effort to find the best way of removing the 

 information. In all of the presentations except 

 one, that of the DELTIC (Delay Line Time 

 Compression), the time that was necessary 

 for the evaluation is indicated. The reason 

 for this exception is that DELTIC operates 

 in real time when processing information. At 

 this stage in the program, however, the 

 DELTIC had to be used in conjunction with 

 some other analyzer. Most of the other tech- 

 niques are very slow and the outputs are 

 sometimes difficult to interpret. In all of 

 these techniques the problem of wow and 

 flutter of the recorder was the limiting fea- 

 ture. 



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