SOURCES OF DATA 



Figure 3 shows the different sources of data used. The most 

 useful were original echograms or soundings with high navigational 

 quality. 



J. C. Sylvester, Bathymetry Division (NAVOCEANO), supplied 

 random soimdings for each chart plus microfilm copies of original 

 echograms and ships' navigational tracks. 



Marine Geophysical Surveys, NAVOCEANO, supplied original echo- 

 grams of detailed cruises in the North Philippine Sea. The ASW/USW 

 Project, NAVOCEANO, under Mr. W. T. Hammond, supplied soundings of 

 extensive surveys in the Sea of Japan. Published charts from the 

 Maritime Safety Agency, Japan and the USSR gave detail in areas 

 where soundings were sparse. 



Echo sounding equipment used to gather data for the charts 

 included the Edo Corporation Sonar Sounding Set AN/UQN-IB, Westrex 

 Corporation Mark V, X, and XV Precision Depth Recorders (PDR), 

 Thomas Gifft Company Depth Recorder (GDR), Alden Electronic and 

 Impulse Recording Equipment Company, Inc., Precision Graphic 

 Recorder (PGR), Alpine Geophysical Associates, Inc., Precision 

 Echo Sovmder Recorder (PESR), and Kelvin-Hughes Echo Sounder. 



EVALUATION OF DATA 



All data was evaluated for its importance in preparing the 

 contour charts and for digitizing into the data bank. Unfortu- 

 nately, many of the random soundings were of veilue in predicting 

 topographic trends but lacked enough precise navigational infor- 

 mation to warrant inclusion in the digital data collection. 



A Isirge segment of the data was shown on charts and sounding 

 sheets contoured in meters, both corrected and uncorrected for 

 sound velocity. These were converted to "uncorrected" fathoms by 

 use of Matthew's Tables of the Velocity of Sound in Pure Water and 

 Sea Water. 



Initially, efforts were made to use digital (computer) output 

 for the chart preparation. However, the random spacing of pre- 

 cision sounding information with precise navigation was insuffi- 

 cient. Therefore, it was necessary to prepare a data tape 

 separately and to develop the charts by visual interpretation and 

 manual cartographic methods with extensive use of stable base 

 materials. 



347 



