Comm meications SSVEN No 3-53 CUTF ropes radio equipment between and within ENIWETOK and BIKINI ATOLLS. The use of voice HF radio equipment will be kept to a minimum for secu- rity reasons and will be closely controlled. Whenever possible, radio teletypewriter facilities will be used for long distance radio communications beyond the range of VHF equipment. Automatic on-line encryption normally will be used in conjunction with such facilities except where off-line encryption is necessary to meet security requirements. Considerable numbers of VHF radio equipment will be used, IT IS MANDATORY THAT CLASSIFIED MATTERS NOT BE DISCUSSED OVER - ANY VOICE RADIO CIRCUITS INCLUDING VHF AND UHF RADIOS. cd. Communication Security . Particular attention will be given to ritintenance of communicatiion security and to speed and accuracy in handling of message traffsiC. e. Joint Relay Center. All organizations within the Pacific Proving Ground will be served by one permanent relay-crypto center at ENIWETOK; installed, operated and maintained by TG 7.2. Tributary stations serviced by this relay center will include Hqs, JTF SEVEN, TG 7.2, 1 7.3 (afloat), TG 7.4 and ships as required, Headquarters, JTF SEVEN communications center (PARRY ISLAND) will protect for TG Tol, TG 7.5 and CIG 7.3 (ashore). In addition, routine naval admin- istrative commmications will be handled through established naval communication facilities. f. Crypto Center. Crypto Center, ENIWETOK, will be crypto guard for all above mentioned tributary stations except CTG 7.3 (afloat) and intra TG 7.3 (ashore) traffic. Radio teletype circuits between the following points will provide rapid communications between major forward and rear echelon task force elements and will be operated with ON-LINE encryption, using SIGTOT and SAMSON (synchronous mixer) for teletype traffic up to and including SECRET, CIRCUIT TYPE ENIWETOK ~ OAHU (UHP) Full Dux (1) ENIWETOK ~ BIKINI Full Dux (1) PARRY - BIKINI (TG 7.1 circuit) Full Dux (1) ENIWETOK - LOS ALAMOS Full Dux (1) ENIWETOK ~ KWAJALEIN Full Dux (13 ENIWETOK - AGC (USS ESTES) Full Dux (1) 411 TOP SECRET and RESTRICTED DATA traffic will be enciphered offline prior to transmission. ‘his is necessary to meet AEC requirements and because terminal communications personnel are not in all instances TOP SECRET or "Q" cleared. g. A full duplex off-line SIGTOT circuit will be operated between the USS BAIROKO and Joint Relay Center, ENIWETOK. h. Telecon Facilities. Telecon facilities will be available at Headquarters, JTF SEVEN (PARRY ISLAND). Requests for this service will be submitted in accordance with COI item 29-1. i. Local Telephone Facilities. Wire telephone facilities cleared for conversations up to and including SECRET will be available at: (1) ENIWETOK ISLAND (400 line dial exchange with connecting service to other islands of ENIWETOK ATOLL). Ink