454 



MECHANICAL AND ACOUSTICAL SENSES 



speeds into a PDP-12 computer 3 to digitize the pulse-interval times. The 

 digital tape thus produced is then processed by the larger CDC-3150 com- 

 puter for further noise reduction, demultiplexing, data averaging (when de- 

 sired), and printout as eight parallel graphs of sensor state vs time of day 

 (Figure 21). 



Biological conclusions are drawn by visual inspection of the computer 

 printouts. Averaged graphs would be scanned first, these including means 

 and ranges for each averaging period. General trends over the day -night cycle 

 would be apparent, and other points of interest would show up— possibly 

 only as range excursions. These would be examined in greater detail on 

 printouts at shorter averaging periods or on full-detail printouts. 



In conjunction with a digital plotter, the computer can be programmed to 

 draw maps showing detailed locomotor patterns of the telemetered sharks. If 



CHANNEL 



1 



MSEC 

 2 S 



5 0_ 







CHANNEL 



2 



"SEC 

 2 5 



8 0_ 







CHjNNEL 



3 



MSEC 



CHANNEL 



4 



HSEC 



CHANNEL 



_ 9 

 "SEC 



CHANNEL 



"SEC 



S ' 



_« 

 



5 2 



5 







.. 1 .. 



« 2 



5 







CHANNEL 



7 



"SEC 

 5 2 « 



OS * 



10 s 



Figure 21 Full-detail computer printouts of simulated multichannel data (rapid multi- 

 plexed). Channels 2, 3, and 7 contain fluctuating data. The millisecond axis for each 

 channel represents the pulse interval in that data frame for that sensor, i.e., changes in 

 millisecond value indicate changes in sensor value. Times on the left margin are based on 

 the time-of-day code (upper left) placed on the tape prior to each recording period. 



An IMSAI 8080 microcomputer is now used for this operation. 



