MVl'/EFS REPORT 76^0 



It can be seen that amplification must be available to overcome 

 attenuation introduced by the cable and winch. As longer lengths of 

 cable are used, signal-to-noise ratios and signal -amplitude variations 

 with cable length shoiald be carefully considered. 



Readout Equipment . The electrical signals transmitted over the 

 cable are amplified, separated into their correct frequency ranges by 

 band-pass filters, and recorded as shown in Fig. 9- 



The electrical signal retui'n path is provided by the conductivity 

 of the sea water. The received signals, after band-pass filtering, can 

 be read on one or more digital counters, can be discriminated and re- 

 corded on X-Y plotters, or recorded on a magnetic tape recorder for 

 playback and analysis. All three methods have been used with the SVTP 

 instrument. IVhen the magnetic recording method is used, frequency 

 errors are introduced into the recorded data of a magnitude dependent 

 upon the tape speed accuracy of the magnetic recorder. To make possible 

 correct interpretation of the frequency data thus recorded, it is 

 necessary to playback concurrently a stable, reference frequency re- 

 corded at the time the instrument data are recorded. From such recorded 

 data on magnetic tape, X-Y plots of sound velocity versus depth and 

 temperature versus depth can be produced. Digital computer tapes can 

 also be produced to give corrected values of sound velocity, temperature, 

 and depth. 



Field Use . Since Aiigust 1959> "the SVTP instrument has been used by 

 WOTS on several cruises in the area of San Clemente Island off the 

 coast of southern California. Figiires 10 and 11 show a pair of typical, 

 simxHtaneously recorded sound velocity and temperature versus depth 

 profiles obtained. 



A report on the data collected on these cruises is now In 

 preparation. 



COUCLUSIOKS AMD RECQ-UffiKDATIONS 



The KOTS-SVTP instrument is a useful oceanographic research tool 

 whose potentialities have not been fully explored. Its advantages are 

 sensitivity; concurrent measurement of soiond velocity, temperat-ure, and 

 pressure; visual display of information; and adaptability to modern data 

 processing methods . 



A model should be developed that could be operated in medium depths 

 of the ocean while the ship is underway. Also a free sinking and free 

 returning model with self-contained recording should be investigated 

 for use in great ocean depths . 



18 



