Step 4. Disconnect On-Off connection on 

 driver cap. GA TJTION : Never luork on circuits 

 with this socket connected. High voltages (8,000 

 V.) are generated when the system is operating. 



Step 5. Attach female socket from battery to 

 driver male plug on underside of end cap. In- 

 spect "O" ring for freedom from cuts, scratches, 

 dirt, etc.; inspect sealing surfaces for cleanli- 

 ness; and apply a light coating of grease to the 

 "O" ring and the sealing surfaces. Make sure 

 "O" ring is seated properly. Replace end cap and 

 tighten the wingbolt thumb tight. 



Step 6. To activate the Sonar pinger connect 

 the On-Off lead. If the pinger is operating, the 

 .5 msc pings will be heard at 1 second intervals ; 

 each 10th ping will be blanked. Do not operate 

 the pinger in air longer than 15 minutes. 



R-5 Theory of Operation. — Operation of the 

 Sonar pinger is automatic. Once the pinger is 

 activated the unit will generate a sound pulse 

 once per second until the battery is discharged 

 or until the unit is turned off. Every 10th pmse 

 is blanked so that the direct and indirect ping 

 can be matched. 



Wlien activated, 6 volts from the battery are 

 applied to the precision-interval, timing- 

 switch motor and to the two transformer 

 coupled transistors. They oscillate at approx- 

 imately 2 KHz, creating a 6-volt alternating 

 current which is raised to about 420 volts in 

 the toroidal power transformer. The 420-volt 

 alternating current is rectified to 840 volts 

 direct current which charges a capacitor. When 

 the capicator discharges into the pulse trans- 

 former, an 8,000-volt pulse is generated and 

 transmitted to the transducer. The secondary 

 of the transfoi-mer and the crystals of the trans- 

 ducer form a tuned circuit which oscillates at 

 about 12 KHz for approximately 0.5 milli- 

 second (about 6 cycles) every second. The 

 sound energy created by the oscillation of the 

 crystals is transmitted through oil to the rubber 

 diaphragm and into the water. 



R-6 Applications of the Sonar Pinger. — 



The Sonar pinger described in this chapter has 

 been used at the U.S. Naval Oceanographic 

 Office to position the underwater camera (see 

 chapter N) and to obtain Nansen cast bottom 

 temperature observations (see paragraph R-7). 

 Other types of pingers which are more compact 

 and lighter weight can be used in the above 

 applications and also can be used in coring 

 operations to determine when the corer touches 

 bottom. These pingers usually are attached to 

 the oceanographic wire in the same manner as 

 a Nansen bottle. 



R-7 Nansen Cast Bottom Positioning Tech- 

 niques. — Figure R-7 presents a standard sup- 

 porting arrangement for the Sonar pinger on 

 a Nansen cast. The pinger assembly, which 



weighs about 150 pounds, replaces the 100- 

 pound lead weight normally used (R-1). Two 

 or three Nansen bottles (2 meters apart) are 

 placed on the wire, with the bottom bottle as 

 near as practical to the pinger. During the 

 lowering of the cast and while the messenger 

 is sliding down the wire, the pinger-to-bottom 

 distance is monitored so that the Nansen bottles 

 with the reversing thermometers will be 

 tripped when they are very near the ocean floor. 



LOWERING 

 WIRE 



NICOPRESS 

 SLEEVES 



PINGER 

 RACK 



Fiffwe R-7. Standard supporting arrangement for 

 Sonar pinger used on Nansen cast. 



R-8. Bottom Positioning Technique.— After 



the pinger is activated and over the side, the 

 lowering should be monitored with the ship's 

 echo sounding equipment, a Precision Depth 

 Recorder (PDR), and an oscilloscope (figs. 

 R-8,R-9,andR-10). 



Step 1. With the ship's echo sounding sys- 

 tem, determine the approximate depth of water 

 in fatlioms, and compute the largest multiple 

 of 400 it contains (400, 800, 1,200, 1,600, 2,000, 

 2,400, 2,800,...). For example 2,603 contains 

 2,400 as the largest multiple of 400. 



Step 2. Set the ship's echo sounding system 

 to the listening mode, and the PDR to the to 

 400 fathom scale. Turn on the oscilloscope, and 

 vary scale illumination by turning control knob 



R-4 



