neers networks through the Army radio relay station in Hawaii and with the Air Force network through Kwajalein. Other radioteletype circuits interconnected Eniwetok Atoll, Bikini Atoll and major ships of the task force, One relay center located on Eniwetok Island served the entire task force and processed all messages leaving the Pacific Proving Grounds except for a minimum number of direct Navy and Air Force communications which were specifically authorized. The USS ESTES (AGC-12) provided alternate carrier wave (CW) service to Hawaii when required. Submarine and land line cable systems connected islands on Eniwetok and Bikini Atolls, The primary radioteletype facility was supplemented by efficient manual and automatic telephone systems and both short and long range voice radio nets. Telephone and voice radio systems were interconnected to provide maximum flexibility. 35. The communications system met the loads placed on it during CASTLE but the operation emphasized the necessity for increased use of fixed station type communications equipment, properly engineered and installed to meet the rigid requirements imposed upon the system, Distances to be covered by radio are long and require high power transmitters, adequate antennae and optimum performance, Land areas are extremely limited and an excessive number of high power radio circuits must be operated within a small area resulting in unusually difficult interference problems. These radio interference problems became more acute when opera- tions were conducted from aboard ship. Intensive efforts and a high degree of technical skill were required to keep all radio circuits operating satisfactorily. Rapid and unexpected changes in test operations required rapid changes in commu- nications networks, emphasizing the need for maximum flexibility. 36. Peak load traffic exceeded fifty-thousand messages and four million groups per month. This amounted to four times the volume handled for a compara- ble period during any previous operation. volume were negligible. Personnel increases to handle this The communications centers and their supporting radio and telephone systems were heavily loaded by the increased traffic but were able to meet it because of improved equipment installed. 37. Operation CASTLE required the integration of commmications systems and practices of the Army, Navy, Air Force, Scientific and Base Facilities Task Groups. The communications succese achieved was, in a large measure, due to the high de~ gree of cooperation and teamwork of commmications personnel of these various task groups, —Copieg LANL, /D0, 4. or -15-