towing vessel) , and discriminated according to channel number and infor- 

 mation content. The discriminated signals are monitored on a six-channel 

 analog recorder for real-time visual observation and for a permanent 

 continuous record. 



c. Analog-Digital Conversion and Recording Modes . Output from the 

 discriminators enters a data logger consisting of several major parts 

 (Fig. 20). The data logger converts the analog signals to digital form, 

 assigns the time to the data points, identifies the channels (sensors), 

 and outputs the digitized data for recording on magnetic tape. 



The data logger (Fig. 21) is a portable alternating or direct current- 

 powered analog to digital converter scanning up to 32 analog channels at 

 the rate of 33.3 channels per second, converting 200 characters per second, 

 each character having six BCD bits. Analog multiplexing is done with 

 COSMOS switches. The unit accepts up to 12 parallel bits of external data 

 recorded in 10 (4-bit) bytes. 



The main feature of the data logger is the system's variable scan rate 

 (Table 1) of 0.333, 1.667, 3.333, 8.333, 16.7, and 33.3 channels per 

 second (BCD formating), limited by the tape recorders' 300-character per 

 second recording speed. Other recorders are available with: higher scan 

 rates up to 1,000 channels per second; 2° and 2 h to 2 12 scans per record 

 and records per file; single, continuous and monitor-scanning modes; auto- 

 matic start at intervals of 10° between 10" 2 and 10 l seconds, 1, 5, 10 

 minutes, and 1,2, and 24 hours with an interval multiplier of 1 to 9 

 (Table 2); choice of end of record (EOR) , end of file (EOF) or no stop, 

 visual monitoring of data and time automatic and manual channel advance, 

 and inter- re cord gap (IRG) or file gap control. 





Table 2. 



Timed start intervals. 











Time Base 

 (Multiplier) 



0.01 

 (s) 



0.1 

 (s) 



1 

 (s) 



10 

 (s) 



1 

 (min) 



5 

 (min) 



10 

 (min) 



1 



(h) 



2 

 (h) 



24 

 (h) 



1 



0.01 



0.1 



1 



10 



1 



5 



10 



1 



2 



1 



2 



0.02 



0.2 



2 



20 



2 



10 



20 



2 



4 



2 



3 



0.03 



0.3 



3 



30 



3 



15 



30 



3 



6 



3 



4 



0.04 



0.4 



4 



40 



4 



20 



40 



4 



8 



4 



5 



0.05 



0.5 



5 



50 



5 



25 



50 



5 



10 



5 



6 



0.06 



0.6 



6 



60 



6 



30 



60 



6 



12 



6 



7 



0.07 



0.7 



7 



70 



7 



35 



70 



7 



14 



7 



8 



0.08 



0.8 



8 



80 



8 



40 



80 



8 



16 



8 



9 



0.09 



0.9 



9 



90 



9 



45 



90 



9 



18 



9 



Data are recorded on a seven track, 556 bits per inch magnetic tape 

 recorder (Fig. 22) which operates on either 110 volts (alternating current) 

 or 12-volts battery power. Data are recorded on 1 .27-centimeter-wide tape 



36 



