Fig 10-9 Hydro Products' Model TC150 underwater television camera (Hydro 

 Products) 



tube. It is interesting to note the peak of 

 spectral response of the SIT tube which is at 

 4,350 Angstroms and somewhat different for 

 the peak response of a "typical" television 

 tube shown in Figure 10.5. 



Vehicle Control 

 Depth Indicators: 



For obvious reasons, every submersible has 

 a depth measuring device, and quite a few 

 carry more than one. Virtually all rely 

 primarily on pressure sensing depth gages, 

 and a number also use an upward-looking 



echo sounder to measure their depth by ping- 

 ing off the surface. Once again, the variety of 

 manufacturers of depth measuring and indi- 

 cating devices is numerous, and in the sub- 

 mersible field no one brand is preferred over 

 another. Consequently, an overview of the 

 principles involved in submersible depth 

 measuring devices serves better than a list of 

 trade names. This approach is taken, and a 

 few examples of systems employed in con- 

 temporary cehicles are described. 



Expandable Metallic Element Cages — The mOSt 



common and widely used design principle in 

 depth measuring devices is found in the 

 Bourdon tube. The Bourdon tube employs a 

 curved or twisted metallic tube flattened in 

 cross section as the sensing element. One 

 end of the tube is sealed and pressure is 

 applied to the opposite, open end. At the 

 onset of applied pressure the tube becomes 

 more nearly circular in cross section and 

 tends to straighten. The movement of the 

 sealed or free end is used to measure the 

 external pressure. The most common "C" 

 tube arrangement is shown in Figure 10.10. 

 Other tube configurations (spiral and helical) 

 are employed when greater tip motion is 

 desired. Bourdon tubes can be used for small 

 pressure measurements (0-10 psig) or large 

 measurements (0-100,000 psig) with accura- 

 cies from 0.1 to 2.0 percent of full scale. 

 These gages are simple, rugged, inexpensive 

 and are used on many vehicles. The means of 



TABLE 10.4 COMPARATIVE DATA ON VIDICON AND SIT CAMERA TUBES [FROM REF. (8)] 



7262AVidicon 



4804/P2 SIT Tube 



Average "Gamma" of Transfer Characteristic 



Lag (% of initial signal current 1/20 second after illumination is removed) 



Limiting Resolution (TV lines) at Center of Picture 



Dark Current at 0.1 Footcandle 



Sensitivity (Ref. Figure 5) 



Typical Gain Ratio Adjustment: 

 Target Voltage (5 to 50 V) 

 Photocathode Voltage (-2.5 to -9 kV) 



Peak of Spectral Response (angstroms) 



100 



5,500 



400 

 4,350 



481 



