on 2.16-meter (8.5 inches) coplanar-mounted reels equivalent to 365.76 

 meters (1,200 feet) of 1.5-mil tape. Recording rate is to 300 characters 

 per second. Data formated as follows: 



FIRST POINT DATA 

 (Date and Time) 



RECORD 



DATA 

 nCHANNELS 



LAST 

 POINT 



OOYDDDHHMMSS 



CCPXXX 



IRG RECORD IRG RECORD 



n RECORDS PER FILE 



Symbols are: Y = year, D = day, H = hour, M = minute, S = second, 

 C = channel number, P = polarity, and X = data. Each record is arranged 

 according to code (each block signifies a bit) : 



7 TRACK 



TIME 



EXT BCD DATA CHANNEL 



DATA 



B 























































 



p 



E 4 

 E 2 



E 1 



A 



















































8 



















D eJ 



D 8 







H 8 







M 8 







s u 



4 



















D 4 * 



4 



D 







4 



H 



46 

 M 



4 



M 



s 4u 



4 



s 



2 













20C 



D 



D 20 



D 2 



H 20 



H 2 



M 20 



tvi 2 



s ;o 



s 2 



1 











Y° 



ri 00 



D'° 



D' 



H 10 



H 



Nl'" 



M ' 



s 10 



s 1 





















































c 8 





80C 



X 



x 80 



x 8 



40 



c 



c 4 





400 



X 



<0 



X 



4 



X 



20 



c 



c 2 





200 



X 



x 20 



x 2 



10 



c 



c 1 





100 



X 



x 10 



x 1 



arity — ' 



Polority- 



Track I 2 4 8 A B 



Plus 1 I 



Minus 1 



Typical files are composed of 2 h scans per record and 2 6 records per 

 file, a total of 1,024 data points per channel. Generally, this is con- 

 sidered a convenient length of information for wave and current data, 

 requiring 4 minutes and 55 seconds of recording time. A comparison of 

 different settings for recording data (Table 3) indicates the time required 

 to record 2 10 data points per channel in the continuous mode can vary be- 

 tween 1,224 and 2,216 seconds. Records in excess of 2 12 words are usually 

 too long for time-series analysis. 



2. System Calibration . 



Several calibration procedures must be observed with TODAS. The first 

 is calibrating the current meters for frequency response, accuracy in re- 

 cording speed and directivity (cosine response), threshold velocity, line- 

 arity, and environmental response (ruggedness) . Coupled to the frequency 

 response and threshold velocity is the bidirectivity of the sensor, i.e., the 



