CHAPTER 5.17 CCMMUNICATIONS The original criteria provided by J-Division established the need for reliable communications between stations located on Parry, Eniwetok, Japtan, the experiment islands, the photo towers, and ships anchored in the lagoon with the center of the Atoll communications system located at Parry. This requirement was particularly vital during the period immediately prior to each experiment, In addition, the armed forces would require the use of communication facilities on Eniwetok and the experiment islands for pre-operational security activities and during operational periods, and construction personnel would utilize commuinications between the various islands during the construction period. In the Reconnaissance Report, various possible types of voice com munications systems were considered, and, as a basis for comparison, a telephone system employing submarine telephone cable trunking was determined to be adequate and reasonable, The proposed location and mm-~ ber of switchboards, instruments, and trunking cables were shown on Plate 49 of the Reconnaissance Report. Various types of telephone instruments and switchboards were discussed, The relative merits of syb- marine telephone cable trunking, radio trunking, and wire and radio with carrier trunking were considered. It was concluded in the Reconnaissance Report that local telephone systems would be required and should be provided for commnication on individual islands and that public address systems should be provided on experiment islands to minimize the mumber of stations and to permit broadcast announcements, Cable trunking between islands was considered the most satisfactory means of communicating between sites because of its simplicity, reliability, resistance to atmospheric conditions, and contribution to security, It was recommended that a radio back-up system be provided, It was further proposed that limited inter-island telephone communication during the construction period could be pro- vided by utilizing submarine control and signal cables for trunking, prior to installation of the communication cables. A decision was reached by the time of Supplement No. 1 to the Re- connaissance Report (July 8, 1949) that a mammal telephone system with submarine cable trunking would be employed, other basic concepts remaining unchanged. This system was designed to utilize common battery rather than magneto service because of the following advantages: 1, Less time and effort by User are required. 2. Automatic signalling is fast and reliable. 3, Work of switchboard operators is reduced. 4. Battery maintenance at telephones is reduced. 5-237