recorder in Rack 2* The other scale, labeled , 



is for use when analyzing tapes from the "high-speed" graphic level recorder 

 in Rack 3° ■ This will be the graphic level tape recording of the magnetic 

 tape recorder playback,. On one scale the second marks are 5 m apart , and 

 on the other scale these marks are 10 mm apart „ 



lllo To use the e^aluator, the operator should let the graphic level recorders 

 run for a sufficient length of time after the recording of the shot to include 

 the next break-second and to insure adequate length of tape for the evaluating 

 device. The tape containing the recording of the shot should be at least 12 

 inches in length „ 



112. To insert the tape into the rule, first determine the speed at which the 

 tape' was recorded (either 5 mm/sec or 10 mm/sec), and then slide the tape 

 under the indicator so that the index marks along the right edge of the tape 

 appear just below the corresponding speed scale. Lift up on the handles 

 located at each end of the body and lift the end gates out of the way Fit 

 the sprocket holes at one end of the tape over the small posts. Close the 

 end gate nearest these posts, being certain it pulls the tape firmly in place 

 without tearing the sprocket holes c At the other end of the body, again pull 

 the tape firmly, avoiding' any tearing of the sprocket holes, and close the 

 end gate. The tape is now ready for evaluation e 



113« It will be noted that on either scale on the indicator there are four 

 different lengths of index lines. The long line is for locatjjig the indicator 

 with respect to the peak amplitude of the shot recording on the graphic level 

 recorder tape The next, largest markings represent the 1-second intervals; 

 the next indicate the l/2~second intervals, and finally the smallest lines 

 are the l/10-second intervals „ 



114o When the graphic level recorder tape containing the recording of the 

 shot has been properly located in the evaluator, move the indicator until 

 the longest line coincides with the exact point on the tape where the abrupt 

 fall-off in signal energy commences (see Fig, 27), Referring to the scale, 

 count back the number of small divisions from the long line to the nearest 

 previous second mark on the tape. The number of small divisions will represent 

 the number of tenths of seconds which must be added to the total time deter- 

 mined for the shot. 



OPERATOR'S MAINTENANCE 



115« In addition to the actual operation of the station as described in 

 USL Report No 55* "Long Distance Sound Ranging Equipment (SOFAR) - Installa- 

 tion and Operating Notes," it is the operator's duty to see that the station 

 is in good condition and at all times ready to function for air-sea rescue 

 The operator should promptly report defects in the equipment which are beyond 

 his responsibility to repair <, 



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