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CHAPTER III 

 DPG HARDWARE 



A. INSTRUMENT, SERVICE BOX, AND CRADLE 



1. Introduction 



The in- situ instrumentation is contained in a poly-vinyl 

 chloride (PVC) structure that is secured to a steel cradle moored to 

 the seafloor. The PVC structure, or "instrument", as it is hereafter 

 called, consists of a central tube, or "fuselage", and four "arms" 

 that extend from near the top of the fuselage. A plexiglass service 

 box, also attached to the cradle, provides storage for eighty feet of 

 unarmored cable at the installation site. Figure III-l illustrates 

 the instrument and Figure III-2 depicts the steel cradle with the 

 instrument in place suspended under the Field Research Facility's 

 CRAB vehicle. 



This chapter describes the DPG system as installed at the 



FRF, Duck, N.C. Several components of the system were altered from 



the original design during DPG assembly and laboratory testing. The 

 discussion of these modifications is presented in Chapter V. 



