CHAPTER XII 



MISC ELLANEOUS D EVICES 



Harbor Protection . 



Among the harbor protective devices were the Cable-Connected 

 Hydrophone system and the Anchored Radio Sonobuoy. 



The Cable -Connected Hydrophone System consisted of a series 

 of regularly spaced tripod-mounted hydrophones connected by sub- 

 marine cable to a shore station where a switching mechanism 

 and a sonic listening amplifier were provided. The system en- 

 abled the forces guarding a harbor to detect end determine the 

 approximate location of an enemy submarine which might approach 

 the harbor entrance, 



The NDRC developmental work en the Cable -Connected Hydro- 

 phone System was done by the New London Laboratory in close 

 cooperation with the Naval Research Laboratory. An initial 

 system was installed near the entrance to Block Island Sound 

 and later, on the basis of experience with this system, a 

 second system was installed at Cape Henry, Virginia. 



Division 6 also contributed materially to the development 

 of the Anchored Radio Sonobuoy e This device worked according 

 to the principle alreadjr discussed in connection with the 

 Expendable Radio Sonobuoy When located in a barber, the 

 anchored buoy picked up underwater sounds and transmitted them 

 by radio to a shore receiving station,. Known as the JM buoy, 

 the original model was developed by the Naval Research Labora- 

 tory for the Navy's Bureau of Ships Division 6 aided in the 

 selection of the hydrophone, made various suggestions for im- 

 provements of the early production models, and helped in 

 personnel training and in the development of methods of anchor- 

 ing and managing the cables to eliminate noise and tangling. 

 The ARSB was reserved for use in deep water and for auxiliary 

 or emergency use at advanced bases where the expenditure of 

 time, material, and effort needed fcr a Cable-Connected Hydro- 

 phone system was not justified. 



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