a day's run the chart running time is correlated with a tide curve for 

 the same time period; depths are therefore corrected to a constant datum. 



6 . Computer Programs 



Radiation measurements are made continuously as the mobile detector 

 system is towed through the surf, along a beach, or along the ocean 

 bottom offshore. Interpretation of the detected radioactivity depends 

 upon the making of maps based on the collation and manipulation of data 

 pertaining to position, observed radiation, and time. With a time- 

 selection mode for data acquisition available at exponential increments 

 of 10 (from 0.01 to 10. 0) seconds, a large mass of data may be accumu- 

 lated in a few hours. During a field test, surveying may go on several 

 hours a day for several weeks, and computer processing is necessary to 

 study and evaluate the collected data. Also, soon after the completion of 

 a survey, plotting and posting of the survey is necessary to efficiently 

 monitor the field operations. Initial field operations at Surf, Cali- 

 fornia, relied on manual preparation of maps and subjective interpreta- 

 tion of data printed by the teletype of the on-board data acquisition 

 system. Almost immediately it became evident that computer processing 

 and plotting must be employed in future operations. Therefore, CERC 

 undertook the in-house development of a computer program that would 

 quickly generate plots useful to continuing field operations. This pro- 

 gram is called RAPLOT. Presently ORNL is developing a more sophisticated 

 program for subsequent study and refinement of the radiation data. The 

 data collected from various sensors are assembled by the on-board de- 

 tector system and punched on 8-channel paper tape in American Standard 

 Code for Information Interchange (ASCII code). At present there are six 

 fields on each line (or card image) of tape containing the data given in 

 Table II. The data on the paper tape is eventually translated to a Binary 

 Coded Decimal (BCD) magnetic tape for use in the RAPLOT program so that 

 it will be compatible with most general purpose computers. 



In addition to the basic field data, some further information, called 

 program control parameters, must be fed into RAPLOT. These parameters 

 supply the location of the shore beacons and the injection site, back- 

 ground radiation count, half life of the isotope, and length of the cable 

 on which the detector was towed. Also supplied are options controlling 

 the format of the plots generated and a legend for the plots. 



The program control cards contain the California Lambert Coordinates 

 of the shore beacons. The data input tape contains the distance to each 

 beacon for each fix. By the Cosine Law, this can be translated into 

 distance in terms of a rectangular coordinate system. 



DX1 = (DB 2 + Dl 2 - D2 2 )/ 2 DB 



DY1 = /oi 2 - DX1 2 



Dl is distance from the upcoast radar beacon, D2 is distance from the 

 downcoast radar beacon, DB is the distance between the two beacons, 



22 



